Biotic Stress

Optimization of crop production can be accomplished only if successful stand establishment is achieved first, since each plant contributes to the total crop yield. Reduction of plant populations after planting will reduce yield and/or quality, even though plants compensate to some degree for stand losses. Successful stand establishment is achieved if factors that affect establishment are known, evaluated, and modified appropriately at the time of field planting. The factors that affect stand establishment are biotic and/or abiotic. Biotic factors are generally pathogens that attack plants as parasites, while abiotic factors are the environmental and physical conditions to which the plant or seed is exposed at the time of planting. Abiotic factors can be classified under three headings: soil, planting requirements, and environmental stress.

Citriculture faces significant constraints in expanding into new environments and agroecological zones. Grafting onto tolerant rootstocks has helped overcome some of these limitations, enabling cultivation under diverse conditions. Nevertheless, citrus production remains vulnerable to multiple abiotic and biotic stressors, among which red mite (Panonychus citri) herbivory can markedly reduce yield and fruit quality. While rootstocks are known to influence scion physiology and defence capacity, their specific role in modulating responses to pest attack is still poorly understood. To address this, we evaluated 18-month-old 'W. Murcott' mandarin grafted onto four citrus rootstocks ('Macrophylla', 'C35', 'Citrumelo', 'Carrizo citrange') under semi-field conditions, infested or not with P. citri. After seven days of infestation (100-160 eggs/leaf), we quantified stress markers (malondialdehyde, proline, salicylic acid), physiological parameters, primary and secondary metabolites, volatile organic compounds (VOCs), and defence-related gene expression. Rootstocks significantly modulated constitutive and inducible responses. 'Citrumelo' and 'Carrizo' showed the lowest MDA accumulation and strongest induction of SA, PR5, and GLR transcripts, coupled with increased emission of herbivory-induced plant volatiles (HIPVs, e.g., b-pinene, methyl salicylate, b-ocimene). 'Macrophylla' exhibited limited changes, whereas 'C35' displayed high MDA content and PITY1 induction, suggesting greater oxidative stress. Photosynthetic pigments declined across all combinations after infestation, while soluble sugars and flavonoids decreased in susceptible rootstocks. VOC profiles shifted both qualitatively and quantitatively in a rootstock-dependent manner. These results show that P. citri herbivory can amplify rootstock-driven differences in physiological, biochemical, and molecular traits, providing a basis for further studies on the role of rootstock–scion interactions in citrus resistance to mite attack.

Plant secondary metabolites (PSM) are small molecules of organic compounds produced in plant metabolism that have various ecological functions, such as defense against pathogens, herbivores, and neighboring plants. They can also help to reduce abiotic stresses, such as drought, salinity, temperature, and UV. This chapter reviewed the ecological functions of the PSM and how people utilize these metabolites to reduce crop biotic and abiotic stresses in agriculture. Specific topics covered in this review are (1) extraction of PSM from plant parts and its application on crops; (2) screening of crop/cover crop germplasms for high PSM content and with resistance to pathogens, herbivores, and/or neighboring plants; (3) regulation of PSM biosynthesis (including plant hormones and defense activators) to increase plant readiness for defense; (4) transcriptome and genome technology improvements in the last decade leading to valuable tools to characterize differential gene expression and gene composition in a genome, and lineage-specific gene family expansion and contraction. In addition, there is a critical need to understand how the biosynthesis and release of allelochemicals occur. Filling this knowledge gap will help us to improve and encourage sustainable weed control practices in agriculture.

Plant secondary metabolites (PSM) are small molecules of organic compounds produced in plant metabolism that have various ecological functions, such as defense against pathogens, herbivores, and neighboring plants. They can also help to reduce abiotic stresses, such as drought, salinity, temperature, and UV. This chapter reviewed the ecological functions of the PSM and how people utilize these metabolites to reduce crop biotic and abiotic stresses in agriculture. Specific topics covered in this review are (1) extraction of PSM from plant parts and its application on crops; (2) screening of crop/cover crop germplasms for high PSM content and with resistance to pathogens, herbivores, and/or neighboring plants; (3) regulation of PSM biosynthesis (including plant hormones and defense activators) to increase plant readiness for defense; (4) transcriptome and genome technology improvements in the last decade leading to valuable tools to characterize differential gene expression and gene c...

for help while conducting the study; Dr V. V. Ramamurthy, Division of Entomology, IARI, New Delhi for help in identifying bee species, and the Director, NRC for Orchids, Pakyong, Sikkim for providing facilities of stereo-zoom microscope. We also thank Dr H. K. Das and Dr K. Ponusamy for their help.

SummaryMenadione sodium bisulphite (MSB) is a water‐soluble derivative of vitamin K3, or menadione, and has been previously demonstrated to function as a plant defence activator against several pathogens in several plant species. However, there are no reports of the role of this vitamin in the induction of resistance in the plant model Arabidopsis thaliana. In the current study, we demonstrate that MSB induces resistance by priming in Arabidopsis against the virulent strain Pseudomonas syringae pv. tomato DC3000 (Pto) without inducing necrosis or visible damage. Changes in gene expression in response to 0.2 mm MSB were analysed in Arabidopsis at 3, 6 and 24 h post‐treatment using microarray technology. In general, the treatment with MSB does not correlate with other publicly available data, thus MSB produces a unique molecular footprint. We observed 158 differentially regulated genes among all the possible trends. More up‐regulated genes are included in categories such as ‘response ...

Grapevine (Vitis vinifera) berries are extremely sensitive to infection by the biotrophic pathogen Erysiphe necator, causing powdery mildew disease with deleterious effects on grape and wine quality. The combined analysis of the transcriptome and metabolome associated with this common fungal infection has not been previously carried out in any fruit. In order to identify the molecular, hormonal, and metabolic mechanisms associated with infection, healthy and naturally infected V. vinifera cv. Carignan berries were collected at two developmental stages: late green (EL33) and early véraison (EL35). RNA sequencing combined with GC–electron impact ionization time-of-flight MS, GC–electron impact ionization/quadrupole MS, and LC–tandem MS analyses revealed that powdery mildew-susceptible grape berries were able to activate defensive mechanisms with the involvement of salicylic acid and jasmonates and to accumulate defense-associated metabolites (e.g. phenylpropanoids, fatty acids). The d...

Vegetable production around the world is more and more hampered by the unfavourable soil and environmental conditions as well as biotic ones as soil-borne pests and diseases. Among all management tactics, vegetable grafting is considered as eco-friendly for sustainable vegetable production as a result of the resistant rootstock reduces the dependency upon agrochemicals needed treating the soil-borne diseases and has opened a new vista in organic farming of vegetables. The production and cultivation of grafted solanaceous and cucurbitaceous plants are ever-increasing across Asia, Europe, and North America because of its ability to provide tolerance to biotic stress and abiotic stresses. These grafted seedlings provide resistance against biotic/abiotic stresses and also increase the yield of the cultivars. At present grafting is regarded as a rapid alternative tool to the relatively slow breeding methodology and helpful in sustainable farming that takes low input for future agriculture system. This tactic has rapidly expanded due to intensification of production practices, reliance on susceptible cultivars to satisfy specific market demands, a global movement and local invasion of novel pathogens, accrued use of organic practices, the fast adoption of high tunnel production systems, use of appropriate technologies for resource-limited farmers and the ban on methyl bromide via Montreal Protocol (Sakata et al. 2007). Further, inventions in mechanised and robotic grafting have given a positive stimulus to this novel ecofriendly approach. Mechanisation can significantly reduce the cost of grafted seedling production in the future. Because of the high post graft mortality of seedlings, this technology is still in infancy in India. For its commercial application in India, sharpening of grafting skills and healing environment need to be standardised.

Abiotic and biotic stresses such as salt stress and fungal infections significantly affect plant growth and productivity, leading to reduced crop yield. Traditional methods of managing stress factors, such as developing resistant varieties, chemical fertilizers, and pesticides, have shown limited success in the presence of combined biotic and abiotic stress factors. Halotolerant bacteria found in saline environments have potential as plant promoters under stressful conditions. These microorganisms produce bioactive molecules and plant growth regulators, making them a promising agent for enhancing soil fertility, improving plant resistance to adversities, and increasing crop production. This review highlights the capability of plant-growth-promoting halobacteria (PGPH) to stimulate plant growth in non-saline conditions, strengthen plant tolerance and resistance to biotic and abiotic stressors, and sustain soil fertility. The major attempted points are: (i) the various abiotic and bio...

CRISPR/Cas9 is a unique technology that has enabled researchers to edit genomes. The current study was conducted to investigate the efficiency of genome editing in diploid and tetraploid potato varieties. The stem internodes of AGB and M6 plants (5-6 weeks old) were infected with Agrobacterium strain LBA4404, harboring CRISPR/Cas9 vector, expressing a particular guide RNA against vacuolar invertase; and Cas9 endonuclease. Both tetraploid and diploid potatoes showed encouraging regenerative response on selection media. The transformation efficiency of 11.7% was obtained in potatoes in this study, whereas an indel% was found to be 6 for diploid and 5 for tetraploid variety via Sanger sequencing data. The regenerated plantlets were shifted to culture tubes where M6 diploid variety needed indole-3-butyric acid (IBA) for root development in comparison to tetraploid variety that rooted without IBA. All molecular analysis confirmed the integration of cassette and expression of Cas9 in primary transformants. Overall, the results concluded that the adopted transformation protocol regenerated plants with edited targeted genes that can be further used in an efficient potato breeding programme. Communicated by J. Zhao.

Multiple abiotic stresses like extreme temperatures, water shortage, flooding, salinity, and exposure to heavy metals are confronted by crop plants with changing climatic patterns. Prolonged exposure to these adverse environmental conditions leads to stunted plant growth and development with significant yield loss in crops. CRISPR-Cas9 genome editing tool is being frequently employed to understand abiotic stress-responsive genes. Noteworthy improvements in CRISPR-Cas technology have been made over the years, including upgradation of Cas proteins fidelity and efficiency, optimization of transformation protocols for different crop species, base and prime editing, multiplex gene-targeting, transgene-free editing, and graft-based heritable CRISPR-Cas9 approaches. These developments helped to improve the knowledge of abiotic stress tolerance in crops that could potentially be utilized to develop knockout varieties and over-expressed lines to tackle the adverse effects of altered climatic patterns. This review summarizes the mechanistic understanding of heat, drought, salinity, and metal stress-responsive genes characterized so far using CRISPR-Cas9 and provides data on potential candidate genes that can be exploited by modern-day biotechnological tools to develop transgene-free genome-edited crops with better climate adaptability. Furthermore, the importance of early-maturing crop varieties to withstand abiotic stresses is also discussed in this review.

Bananas (Musa spp.) are vital to global food security and trade, but their climacteric ripening leads to rapid spoilage and post-harvest losses. Conventional ripening control methods, such as cold storage and chemical treatments, often lack efficiency and sustainability. CRISPR/Cas9-based genome editing has emerged as a precise and promising alternative for modulating fruit ripening by targeting key ethylene biosynthesis genes. This review examines the molecular regulation of banana ripening, emphasizing the role of MaACO1 and MaACS1 in ethylene production. CRISPR-mediated knockouts of these genes have demonstrated significant potential in delaying ripening without introducing foreign DNA, offering a more efficient and publicly acceptable alternative to conventional breeding and transgenic methods.We further discuss the challenges and future perspectives of CRISPR applications in banana improvement, including regulatory frameworks, offtarget effects, and consumer acceptance. Integrating genome editing with existing post-harvest strategies can reduce losses, enhance sustainability, and improve the economic viability of banana production. This review provides insights into the latest advancements in CRISPR-Cas systems for fruit ripening modulation, with a focus on their transformative potential for the banana industry.

Legumes are among the most important crops globally, serving as a major food source for protein and oil. In tropical regions, the cultivation of legumes has expanded significantly due to the increasing demand for food, plant-based products, and sustainable agriculture practices. However, tropical environments pose unique challenges, including high temperatures, erratic rainfall, soil infertility, and a high incidence of pests and diseases. Indeed, legumes are vulnerable to infections caused by bacteria, fungi, oomycetes, viruses, and nematodes. This review highlights the importance of legumes in tropical farming and discusses major diseases affecting productivity and their impact on the economy, environment, and lives of smallholder legume farmers. We emphasize the use of legume genetic resources and breeding, and biotechnology innovations to foster resistance and address the challenges posed by pathogens in legumes. However, an integrated approach that includes other cultivation techniques (e.g., crop rotation, rational fertilization, deep plowing) remains important for the prevention and control of diseases in legume crops. Finally, we highlight the contributions of plant genetic resources to smallholder resilience and food security.

Plants have the ability to recognize and respond to a multitude of pathogens, resulting in a massive reprogramming of the plant to activate defense responses including Resistance (R) and Pathogenesis-Related (PR) genes. Abiotic stresses can also activate PR genes and enhance pathogen resistance, representing valuable genes for breeding purposes. The present work offers an overview of soybean R and PR genes present in the GENOSOJA (Brazilian Soybean Genome Consortium) platform, regarding their structure, abundance, evolution and role in the plantpathogen metabolic pathway, as compared with Medicago and Arabidopsis. Searches revealed 3,065 R candidates (756 in Soybean, 1,142 in Medicago and 1,167 in Arabidopsis), and PR candidates matching to 1,261 sequences (310, 585 and 366 for the three species, respectively). The identified transcripts were also evaluated regarding their expression pattern in 65 libraries, showing prevalence in seeds and developing tissues. Upon consulting the SuperSAGE libraries, 1,072 R and 481 PR tags were identified in association with the different libraries. Multiple alignments were generated for Xa21 and PR-2 genes, allowing inferences about their evolution. The results revealed interesting insights regarding the variability and complexity of defense genes in soybean, as compared with Medicago and Arabidopsis.

In higher eukaryotes, the genes' architecture has become an essential determinant of the variation in the number of transcripts (expression level) and the specificity of gene expression in plant tissue under stress conditions. The modern rise in genome-wide analysis accounts for summarizing the essential factors through the translocation of gene networks in a regulatory manner. Stress tolerance genes are in two groups: structural genes, which code for proteins and enzymes that directly protect cells from stress (such as genes for transporters, osmo-protectants, detoxifying enzymes, etc.), and the genes expressed in regulation and signal transduction (such as transcriptional factors (TFs) and protein kinases). The genetic regulation and protein activity arising from plants' interaction with minerals and abiotic and biotic stresses utilize high-efficiency molecular profiling. Collecting gene expression data concerning gene regulation in plants towards focus predicts an acceptable model for efficient genomic tools. Thus, this review brings insights into modifying the expression study, providing a valuable source for assisting the involvement of genes in plant growth and metabolism-generating gene databases. The manuscript significantly contributes to understanding gene expression and regulation in plants, particularly under stress conditions. Its insights into stress tolerance mechanisms have substantial implications for crop improvement, making it highly relevant and valuable to the field.

Arbuscular mycorrhizal associations imply a remarkable reprogramming of functions in both plant and fungal symbionts. The consequent alterations on plant physiology have a clear impact on the plant response to biotic stresses. In this chapter we discuss the effects of the mycorrhizal symbiosis on plant susceptibility/resistance to potential deleterious organisms, including root and shoot pathogens, root parasitic plants and phytophagous insects, highlighting the mechanisms that may be operating in each particular case. Special attention is given to the modulation of plant defence responses in mycorrhizal systems, as it may affect all interactions. Finally we focus on the priming of jasmonate regulated plant defence mechanisms that seem to mediate the induction of resistance by arbuscular mycorrhizas.

Dioxins are highly hazardous pollutants that have well characterized impacts on both animal and human health. However, the biological effects of dioxins on plants have yet to be described in detail. Here we describe a dioxin-inducible caleosin/peroxygenase isoform, PdPXG2, that is mainly expressed in the apical zone of date palm roots and specifically reduces 9-hydroperoxide fatty acids. A characteristic spectrum of 18 dioxin-responsive oxylipin (DROXYL) congeners was also detected in date palm roots after exposure to dioxin. Of particular interest, six oxylipins, mostly hydroxy fatty acids, were exclusively formed in response to TCDD. The DROXYL signature was evaluated in planta and validated in vitro using a specific inhibitor of PdPXG2 in a root-protoplast system. Comparative analysis of root suberin showed that levels of certain monomers, especially the mono-epoxides and trihydroxides of C16:3 and C18:3, were significantly increased after exposure to TCDD. Specific inhibition of PdPXG2 activity revealed a positive linear relationship between deposition of suberin in roots and their permeability to TCDD. The results highlight the involvement of this peroxygenase in the plant response to dioxin and suggest the use of dioxin-responsive oxylipin signatures as biomarkers for plant exposure to this important class of xenobiotic contaminants.

In an agroecosystem, plants and microbes coexist and interact with environmental factors such as climate, soil, and pests. However, agricultural practices that depend on chemical fertilizers, pesticides, and frequent tillage often disrupt the beneficial interactions in the agroecosystem. To reconcile the improvement of crop performance and reduction in environmental impacts in agriculture, we need to understand the functions of the complex interactions and develop an agricultural system that can maximize the potential benefits of the agroecosystem. Therefore, we are developing a system called the agroecosystem engineering system, which aims to optimize the interactions between crops, microbes, and environmental factors, using multi-omics analysis. This review first summarizes the progress and examples of omics approaches, including multi-omics analysis, to reveal complex interactions in the agroecosystem. The latter half of this review discusses the prospects of data analysis approa...

A primary focus of the rapidly growing field of plant synthetic biology is to develop technologies to precisely regulate gene expression and engineer complex genetic circuits into plant chassis. At present, there are few orthogonal tools available for effectively controlling gene expression in plants, with most researchers instead using a limited set of viral elements or truncated native promoters. A powerful repressible-and engineerable-binary system that has been repurposed in a variety of eukaryotic systems is the Q-system from Neurospora crassa. Here, we demonstrate the functionality of the Q-system in plants through transient expression in soybean (Glycine max) protoplasts and agroinfiltration in Nicotiana benthamiana leaves. Further, using functional variants of the QF transcriptional activator, it was possible to modulate the expression of reporter genes and to fully suppress the system through expression of the QS repressor. As a potential application for plant-based biosensors (phytosensors), we demonstrated the ability of the Q-system to amplify the signal from a weak promoter, enabling remote detection of a fluorescent reporter that was previously undetectable. In addition, we demonstrated that it was possible to coordinate the expression of multiple genes through the expression of a single QF activator. Based on the results from this study, the Q-system represents a powerful orthogonal tool for precise control of gene expression in plants, with envisioned applications in metabolic engineering, phytosensors, and biotic and abiotic stress tolerance.

A primary focus of the rapidly growing field of plant synthetic biology is to develop technologies to precisely regulate gene expression and engineer complex genetic circuits into plant chassis. At present, there are few orthogonal tools available for effectively controlling gene expression in plants, with most researchers instead using a limited set of viral elements or truncated native promoters. A powerful repressible-and engineerable-binary system that has been repurposed in a variety of eukaryotic systems is the Q-system from Neurospora crassa. Here, we demonstrate the functionality of the Q-system in plants through transient expression in soybean (Glycine max) protoplasts and agroinfiltration in Nicotiana benthamiana leaves. Further, using functional variants of the QF transcriptional activator, it was possible to modulate the expression of reporter genes and to fully suppress the system through expression of the QS repressor. As a potential application for plant-based biosensors (phytosensors), we demonstrated the ability of the Q-system to amplify the signal from a weak promoter, enabling remote detection of a fluorescent reporter that was previously undetectable. In addition, we demonstrated that it was possible to coordinate the expression of multiple genes through the expression of a single QF activator. Based on the results from this study, the Q-system represents a powerful orthogonal tool for precise control of gene expression in plants, with envisioned applications in metabolic engineering, phytosensors, and biotic and abiotic stress tolerance.

Adzuki bean (Vigna angularis) is one of the most important legume crops in Asian countries like China, Japan and Korea due to its nutritious protein and starch contents. In spite of its economic importance, gene expression analysis system for gene function verification of adzuki bean is still absent. Therefore, reference genes for gene expression analysis based on the quantitative real time PCR (qRT-PCR) were screened in current study. A total of nine general housekeeping genes, including ACT, Fbox, ZMPP, GAPDH, EF, PP2A, UBC, UBN and PTB were evaluated for their expression stability by qRT-PCR in four adzuki bean cultivars, three different tissues, four abiotic stress and one biotic stress. The best group of candidates as reference genes were as follows: PTB and ACT for different cultivars; EF and UBN for different tissues; ACT and ZMPP for biotic stress and waterlogging stress; Fbox and UBC for salinity-alkalinity stress; Fbox and PTB for drought stress. Our results will provide a more accurate and reliable normalization of qRT-PCR data in adzuki bean.

Plants are constantly exposed to environmental stresses during their growth and development. Owing to their immobility, plants possess stress-sensing abilities and adaptive responses to cope with the abiotic and biotic stresses caused by extreme temperatures, drought, flooding, salinity, heavy metals and pathogens. Acyl-CoA-binding proteins (ACBPs), a family of conserved proteins among prokaryotes and eukaryotes, bind to a variety of acyl-CoA esters with different affinities and play a role in the transport and maintenance of subcellular acyl-CoA pools. In plants, studies have revealed ACBP functions in development and stress responses through their interactions with lipids and protein partners. This review summarises the roles of plant ACBPs and their lipid and protein interactors in abiotic and biotic stress responses.

Plants are constantly exposed to environmental stresses during their growth and development. Owing to their immobility, plants possess stress-sensing abilities and adaptive responses to cope with the abiotic and biotic stresses caused by extreme temperatures, drought, flooding, salinity, heavy metals and pathogens. Acyl-CoA-binding proteins (ACBPs), a family of conserved proteins among prokaryotes and eukaryotes, bind to a variety of acyl-CoA esters with different affinities and play a role in the transport and maintenance of subcellular acyl-CoA pools. In plants, studies have revealed ACBP functions in development and stress responses through their interactions with lipids and protein partners. This review summarises the roles of plant ACBPs and their lipid and protein interactors in abiotic and biotic stress responses.

Background: MicroRNA-regulation of gene expression plays a key role in the development and response to biotic and abiotic stresses. Deep sequencing analyses accelerate the process of small RNA discovery in many plants and expand our understanding of miRNA-regulated processes. We therefore undertook small RNA sequencing of sugarcane miRNAs in order to understand their complexity and to explore their role in sugarcane biology. Results: A bioinformatics search was carried out to discover novel miRNAs that can be regulated in sugarcane plants submitted to drought and salt stresses, and under pathogen infection. By means of the presence of miRNA precursors in the related sorghum genome, we identified 623 candidates of new mature miRNAs in sugarcane. Of these, 44 were classified as high confidence miRNAs. The biological function of the new miRNAs candidates was assessed by analyzing their putative targets. The set of bona fide sugarcane miRNA includes those likely targeting serine/threonine kinases, Myb and zinc finger proteins. Additionally, a MADS-box transcription factor and an RPP2B protein, which act in development and disease resistant processes, could be regulated by cleavage (21-nt-species) and DNA methylation (24-nt-species), respectively. Conclusions: A large scale investigation of sRNA in sugarcane using a computational approach has identified a substantial number of new miRNAs and provides detailed genotype-tissue-culture miRNA expression profiles. Comparative analysis between monocots was valuable to clarify aspects about conservation of miRNA and their targets in a plant whose genome has not yet been sequenced. Our findings contribute to knowledge of miRNA roles in regulatory pathways in the complex, polyploidy sugarcane genome.

Striga gesnerioides (Wild.) Vatke is the main biotic factor restricting yield of cowpea in Sub-Saharan Africa (SSA) in general and particularly in Niger. To date, seven different races infesting cowpea have been identified in Africa based on differential responses of cowpea varieties. It was desirable to verify whether there are other Striga races a part from the race SG3 reported so far in Niger. Field and pots experiments were conducted during two years in order to identify the different Striga races that infest cowpea in the country. Fifteen genotypes were screened under natural infestation in field as well as inoculated in pots with three samples of the parasitic weed collected in three hot spots. The test revealed Striga attack on three multiracial Striga resistant varieties: B301, IT97K-499-35 and IT98K-205-8 suggesting the presence of other races like SG4 Z in the studied area, or the breakdown of the resistance to Striga race SG3 in these cowpea varieties. Also, the resistance of HTR and Suvita 2 observed respectively in field at Kollo and in pots with Magaria sample suggested the prevalence of Striga race SG1 in these sites. From these observations, the geographical distribution of Striga races needs to be clarified in Niger and the extent to which two or more races can be associated in field requires further investigations.

We present a green synthesis method of producing blue fluorescence emitting carbon nanoparticles (CNPs) through a simple and cost-effective single-step hydrothermal reaction. The synthesis utilized bract extracts and pollen grains from threeBougainvilleaspecies:B. spectabilis, B. alba, andB. buttiana. The CNPs exhibited photoluminescence, with the highest emission observed in the ultraviolet region. Atomic force microscopy analysis revealed that the size of synthesized CNPs ranged from 23 nm to 83 nm. Fourier transform infrared analysis provided a comprehensive understanding of the CNP’s surface functional groups, with carbon being the predominant group. X-ray diffraction analysis confirmed the amorphous nature of the synthesized CNPs. Zeta potential measurements indicated that the particles carried a negative charge, suggesting their colloidal stability. In experiments conducted withArabidopsis thalianaseedlings, CNPs derived fromB. albapollen grains were found to promote leaf area...

Agricultural crops are subject to a variety of biotic and abiotic stresses that adversely affect growth and reduce the yield of crop plantss. Traditional crop stress management approaches are not capable of fulfilling the food demand of the human population which is projected to reach 10 billion by 2050. Nanobiotechnology is the application of nanotechnology in biological fields and has emerged as a sustainable approach to enhancing agricultural productivity by alleviating various plant stresses. This article reviews innovations in nanobiotechnology and its role in promoting plant growth and enhancing plant resistance/tolerance against biotic and abiotic stresses and the underlying mechanisms. Nanoparticles, synthesized through various approaches (physical, chemical and biological), induce plant resistance against these stresses by strengthening the physical barriers, improving plant photosynthesis and activating plant defense mechanisms. The nanoparticles can also upregulate the expression of stress-related genes by increasing anti-stress compounds and activating the expression of defense-related genes. The unique physico-chemical characteristics of nanoparticles enhance biochemical activity and effectiveness to cause diverse impacts on plants. Molecular mechanisms of nanobiotechnology-induced tolerance to abiotic and biotic stresses have also been highlighted. Further research is needed on efficient synthesis methods, optimization of nanoparticle dosages, application techniques and integration with other technologies, and a better understanding of their fate in agricultural systems.

The study of senescence in plants is complicated by diverse levels of temporal and spatial dynamics as well as the impact of external biotic and abiotic factors and crop plant management. Whereas the molecular mechanisms involved in developmentally regulated leaf senescence are very well understood, in particular in the annual model plant species Arabidopsis, senescence of other organs such as the flower, fruit, and root is much less studied as well as senescence in perennials such as trees. This review addresses the need for the integration of multi-omics techniques and physiological phenotyping into holistic phenomics approaches to dissect the complex phenomenon of senescence. That became feasible through major advances in the establishment of various, complementary 'omics' technologies. Such an interdisciplinary approach will also need to consider knowledge from the animal field, in particular in relation to novel regulators such as small, non-coding RNAs, epigenetic control and telomere length. Such a characterization of phenotypes via the acquisition of high-dimensional datasets within a systems biology approach will allow us to systematically characterize the various programmes governing senescence beyond leaf senescence in Arabidopsis and to elucidate the underlying molecular processes. Such a multi-omics approach is expected to also spur the application of results from model plants to agriculture and their verification for sustainable and environmentally friendly improvement of crop plant stress resilience and productivity and contribute to improvements based on postharvest physiology for the food industry and the benefit of its customers.

Bacterial Blight (BB) caused by Xanthomonas oryzae pv. oryzae is one of the most devasting diseases in rice which causes significant yield loss. The present study was conducted at the Department of Plant Breeding and Genetics, College of Agriculture Vellanikkara, Kerala to screen rice accessions for BB response. One hundred and fifty rice genotypes along with resistant and susceptible checks were assessed for BB at the seedling stage using the artificial inoculation method and were scored based on IRRI, SES, 2014. Among the 150 rice genotypes screened, 5 genotypes scored resistant (R), 26 moderately resistant (MR), 85 moderately susceptible (MS), and 34 susceptible (S) reaction to BB incidence. Among the tested genotypes, Karuthamodan (1.22%), Pallipuram Pokkali (1.53%), and Tulasi (5.25%) showed minimum disease leaf area percentage for the disease incidence while IET 18318 Sel 2 (40.27%), Japan violet (37.03%), and Erunazhi (35.85%), showed maximum disease leaf area percentage. The...

Biotic and abiotic stresses impose a major threat to agriculture. Therefore, the efforts to develop stresstolerant plants are of immense importance to increase crop productivity. In recent years, tissue culture based in vitro selection has emerged as a feasible and cost-effective tool for developing stress-tolerant plants. Plants tolerant to both the biotic and the abiotic stresses can be acquired by applying the selecting agents such as NaCl (for salt tolerance), PEG or mannitol (for drought tolerance) and pathogen culture filtrate, phytotoxin or pathogen itself (for disease resistance) in the culture media. Only the explants capable of sustaining such environments survive in the long run and are selected. In vitro selection is based on the induction of genetic variation among cells, tissues and/or organs in cultured and regenerated plants. The selection of somaclonal variations appearing in the regenerated plants may be genetically stable and useful in crop improvement. This review focuses on the progress made towards the development of stress-tolerant lines through tissue culture based in vitro selection. Plants have evolved many biochemical and molecular mechanisms to survive under stress conditions. The mechanisms of ROS (reaction oxygen species) generation and removal in plants under biotic and abiotic stress conditions have also been reviewed.

Over time plants developed complex mechanisms in order to adapt themselves to the environment. Plant innate immunity is one of the most important mechanisms for the environmental adaptation. A myriad of secondary metabolites with nutraceutical features are produced by the plant immune system in order to get adaptation to new environments that provoke stress (stressors). Hormesis is a phenomenon by which a stressor (i.e., toxins, herbicides, etc.) stimulates the cellular stress response, including secondary metabolites production, in order to help organisms to establish adaptive responses. Hormetins of biotic origin (i.e., biostimulants or biological control compounds), in certain doses might enhance plant performance, however, in excessive doses they are commonly deleterious. Biostimulants or biological control compounds of biotic origin are called "elicitors" that have widely been studied as inducers of plant tolerance to biotic and abiotic stresses. The plant response to...

This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Neurotransmitter molecules such as serotonin and melatonin have been well studied for their de ned role in animal systems. These molecules have also been reported in various genera of plants. In recent years, the precise function of these compounds in plant systems has been a subject of intense study. The understanding of the biosynthetic pathway of serotonin and melatonin in higher plants has been unfolding. The derivatives of serotonin and melatonin also play a signi cant role in plant adaptations. In recent years, the role of melatonin and serotonin in plant morphogenesis has been gathering attention. There is speculation of the possible role of serotonin and melatonin as candidate hormones owing to their structural similarity with the plant hormone, indole acetic acid. Their role in adaptive functions to environmental conditions and stresses in plants is of continued research interest. This book makes a bold attempt to bring together current understanding of and developments in serotonin and melatonin biosynthesis; and their role in ontogeny and environmental adaptation in plants; levels in food and medicinal plants; involvement and implication of endogenous serotonin and melatonin, and from dietary sources to human health, based on the world literature and authors' data from their laboratories. The above aspects have been described in detail in this book, and the following points provide the focus at a glance. The editors would like to thank all the contributors to this volume, which is a comprehensive treatise on the topic. We understand that the contributors are active scientists and have volunteered to share their ndings and perspectives with the readers, who will bene t from learning about the implications and applications of the subject matter of the book as emerging areas of science. We are grateful to John Sulzycki, Jill J. Jurgensen, and the team from Taylor & Francis, as well as Michelle van Kampen and the Deanta team, for their help in bringing out the volume in a beautiful and appealing manner. We are both thankful to our families, who have encouraged us to undertake this task and permitted us to take time off from the family. G.A.R. thanks his wife Shyla, son Prashanth, daughter-in-law Vasudha, and daughter Apoorva. A.R. thanks his wife Venkatalaxmi, and children Hasini and Jashvitha, and brother Mr. Pakkirappa. G.A.R. is also thankful to the management of Dayananda Sagar Institutions for granting permission to take time out for this work. A.R. is thankful to Monsanto Crop Breeding center, Bengaluru, for their support. We thank the Department of Science and Technology, Government of India, for providing the grant for our research carried out on this topic by us at the Central Food Technological Research Institute (CFTRI) at Mysore. We also thank the staff and students of the Plant Cell Biotechnology Department, CFTRI; and other colleagues, especially Dr.

Plant genomes are massively invaded by transposable elements (TEs), many of which are located near host genes and can thus impact gene expression. In flowering plants, TE expression can be activated (de-repressed) under certain stressful conditions, both biotic and abiotic, as well as by genome stress caused by hybridization. In this study, we examined the effects of these stress agents on TE expression in two diploid species of coffee, Coffea canephora and C. eugenioides, and their allotetraploid hybrid C. arabica. We also explored the relationship of TE repression mechanisms to host gene regulation via the effects of exonized TE sequences. Similar to what has been seen for other plants, overall TE expression levels are low in Coffea plant cultivars, consistent with the existence of effective TE repression mechanisms. TE expression patterns are highly dynamic across the species and conditions assayed here are unrelated to their classification at the level of TE class or family. In contrast to previous results, cell culture conditions per se do not lead to the de-repression of TE expression in C. arabica. Results obtained here indicate that differing plant drought stress levels relate strongly to TE repression mechanisms. TEs tend to be expressed at significantly higher levels in non-irrigated samples for the drought tolerant cultivars but in drought sensitive cultivars the opposite pattern was shown with irrigated samples showing significantly higher TE expression. Thus, TE genome repression mechanisms may be finely tuned to the ideal growth and/or regulatory conditions of the specific plant cultivars in which they are active. Analysis of TE expression levels in cell culture conditions underscored the importance of nonsense-mediated mRNA decay (NMD) pathways in the repression of Coffea TEs. These same NMD mechanisms can also regulate plant host gene expression via the repression of genes that bear exonized TE sequences.

Salinity is linked to poor plant growth and a reduction in global food output. Therefore, there is an essential need for plant adaptation and mitigation of salinity stress conditions. Plants combat salinity stress influences by promoting a set of physiological, biochemical, and molecular actions. Tremendous mechanisms are being applied to induce plant stress tolerance, involving amino acid application. For evaluating the growth and productivity of Moringa oleifera trees grown under salt stress conditions, moringa has been cultivated under different levels of salinity and subjected to a foliar spray of proline (Pro) and phenylalanine (Phe) amino acids. Moringa plants positively responded to the lowest level of salinity as the leaves, inflorescences, seeds, and oil yields have been increased, but the growth and productivity slightly declined with increasing salinity levels after that. However, Pro and Phe applications significantly ameliorate these effects, particularly, Pro-treatment...

Bauhinia acuminata L., known as စွ ယ် တော်  in Myanmar, is a traditional medicinal plant with significant potential for controlling Aspergillus contamination in agriculture, addressing critical challenges posed by Aspergillus niger and Aspergillus flavus in crop spoilage and aflatoxin production. This paper explores the plant's phytochemical profile, including flavonoids, phenolics, tannins, and alkaloids, which exhibit moderate antifungal activity (8-10 mm inhibition zones against A. niger) through mechanisms such as ergosterol disruption and oxidative stress induction. Green synthesis of silver (AgNPs) and zinc oxide nanoparticles (ZnONPs) using Bauhinia acuminata extracts enhances antifungal efficacy, with studies on related Bauhinia species reporting 12-15 mm inhibition zones. These nanoparticles offer eco-friendly solutions for crop protection, post-harvest storage, and aflatoxin mitigation, suitable for Myanmar's resourceconstrained agricultural sector. By integrating traditional Myanmar medicinal practices with modern nanotechnology, this approach reduces reliance on chemical fungicides, supporting sustainable agriculture and food security. However, challenges such as limited field trials, lack of specific studies on A. flavus, and nanoparticle safety concerns necessitate further research. Future directions include field trials, aflatoxin inhibition studies, synthesis optimization, safety assessments, and community collaboration to ensure practical implementation in Myanmar and other tropical regions.

Plant growth and development are positively regulated by the endophytic microbiome via both direct and indirect perspectives. Endophytes use phytohormone production to promote plant health along with other added benefits such as nutrient acquisition, nitrogen fixation, and survival under abiotic and biotic stress conditions. The ability of endophytes to penetrate the plant tissues, reside and interact with the host in multiple ways makes them unique. The common assumption that these endophytes interact with plants in a similar manner as the rhizospheric bacteria is a deterring factor to go deeper into their study, and more focus was on symbiotic associations and plant–pathogen reactions. The current focus has shifted on the complexity of relationships between host plants and their endophytic counterparts. It would be gripping to inspect how endophytes influence host gene expression and can be utilized to climb the ladder of “Sustainable agriculture.” Advancements in various molecula...

The genetic diversity in 128 exotic pea accessions from diverse origin was determined for four qualitative traits flower color (FC), testa color (TC), cotyledon color (CC) and pod shape (PS) and eleven quantitative attributes i.e., plant height (PH), total pod number (TPN), number of pods per plant (NOPPP), total pod weight (TPW), pod weight per plant (PEPP), average pod length (APL), average pod width (APW), average pod thickness (APT), seed weight (SW), seed weight per plant (SWPP) and seed index (SI) through statistical software using a nonhierarchical, PCA. The projection of attributes on PC1 and PC2 revealed that average pod thickness, average pod length and average pod width are positively correlated to weight per pod. The projection pattern of the attributes on first two PCs depicted that key pod weight contributing attributes were pod thickness, length and width while the cotyledon color was opposite to weight per pod and other yield contributing traits on PC1, therefore, it...

• Although the significant number of reports on plants carrying transgenes conferring specific characteristics, little is known about plant-specific promoters, mainly those that are agronomically relevant, such as cotton and soybean. This review highlights promising plant promoters applied to molecular breeding and conserved cis-acting elements from promoters responsive to different biotic stresses in soybean, raising new possibilities for constructing synthetic and optimized promoters.

embryos were used to establish callus cultures in MS modified medium. Cell lines calli were then submitted to increasing concentrations (0, 4, 8, 12, 16 g.L-1) of NaCl. Therefore growth, water and ions contents (K + , Na + and Cl - ) were determined in both the control (unselected wild-type calli maintained in salt-free medium) and selected (tolerant and sensitive genotypes) calli. Selected salt-tolerant calli showed no growth reduction in comparison with the control when treated with 16 g.L-1 NaCl while a significant growth decrease was noted in salt-sensitive ones. Water content was significantly higher in salt- tolerant calli than in salt-sensitive ones. Both tolerant and sensitive calli accumulated less K+ than the control but K+ content of salt-tolerant calli remained higher than that of salt-sensitive ones. Accumulation of Na+ and Cl- was higher in salt-sensitive calli than in salt-tolerant ones with Na+ increase being the highest. The results indicated that Na+ especially but...

Background Wild rocket (Diplotaxis tenuifolia) is prone to soil-borne stresses under intensive cultivation systems devoted to ready-to-eat salad chain, increasing needs for external inputs. Early detection of the abiotic and biotic stresses by using digital reflectance-based probes may allow optimization and enhance performances of the mitigation strategies. Methods Hyperspectral image analysis was applied to D. tenuifolia potted plants subjected, in a greenhouse experiment, to five treatments for one week: a control treatment watered to 100% water holding capacity, two biotic stresses: Fusarium wilting and Rhizoctonia rotting, and two abiotic stresses: water deficit and salinity. Leaf hyperspectral fingerprints were submitted to an artificial intelligence pipeline for training and validating image-based classification models able to work in the stress range. Spectral investigation was corroborated by pertaining physiological parameters. Results Water status was mainly affected by w...

BackgroundWild rocket (Diplotaxis tenuifolia) is prone to soil-borne stresses under intensive cultivation systems devoted to ready-to-eat salad chain, increasing needs for external inputs. Early detection of the abiotic and biotic stresses by using digital reflectance-based probes may allow optimization and enhance performances of the mitigation strategies.Methodshyperspectral image analysis was applied to D. tenuifolia potted plants subjected, in a greenhouse experiment, to five treatments for one week: a control treatment watered to 100% water holding capacity, two biotic stresses: Fusarium wilting and Rhizoctonia rotting, and two abiotic stresses: water deficit and salinity. Leaf hyperspectral fingerprints were submitted to an artificial intelligence pipeline for training and validating image-based classification models able to work in the stress range. Spectral investigation was corroborated by pertaining physiological parameters. ResultsWater status was mainly affected by water...

Plants being sessile are under constant threat of multiple abiotic and biotic stresses within its natural habitat. A combined stress involving an abiotic and a biotic factor reportedly increases susceptibility of the plants to pathogens. The emerging threat, collar rot disease of chickpea (caused by Sclerotium rolfsii Sacc.) is reported to be influenced by soil moisture condition (SMC). Hence, we studied the influence of differential SMC viz. upper optimum (100%), optimum (80%), lower optimum (60%), and limiting (40%) soil moisture conditions on colonization and collar rot development over the course of infection in two chickpea cultivars, Annigeri (susceptible to collar rot) and ICCV 05530 (moderately resistant to collar rot). Disease incidence was found to be directly proportional to increase in soil moisture (R 2 = 0.794). Maximum incidence was observed at 80% SMC, followed by 100 and 60% SMC. Expression of genes (qPCR analysis) associated with host cell wall binding (lectin) and degradation viz. endopolygalacturonase-2, endoglucosidase, and cellobiohydrolase during collar rot development in chickpea were relatively less at limiting soil moisture condition (40%) as compared to optimum soil moisture condition (80%). As compared to individual stress, the expression of defense response genes in chickpea seedlings were highly up-regulated in seedlings challenged with combined stress. Our qPCR results indicated that the expression of defense-related genes in chickpea during interaction with S. rolfsii at low SMC was primarily responsible for delayed disease reaction. Involvement of moisture and biotic stress-related genes in combined stress showed a tailored defense mechanism.

Endophytic bacteria play many important beneficial roles in the metabolism and physiology of the host plants, including fixing atmospheric nitrogen, solubilizing phosphates, synthesizing phytohormones, sequestrating iron, suppression of the ethylene production, and inhibiting pathogens. The present study was conducted to screen and identify endophytic bacterial species with plant growth-promotion, biotic and abiotic stress tolerance properties to develop bio inoculants. For this purpose, root and seed samples of different cultivated tef varieties were collected. A total of 195 pure endophytic bacterial colonies were isolated and screened for PGP traits, biotic and abiotic stress tolerance factors. Fourteen endophytic bacterial species or strains were identified using the Biolog microbial identification system. Among the identified endophytes, the majority of them utilized different carbon sources tagged on microplates. Three potential endophytic bacterial species or strains were evaluated for seed germination and seedling growth ability using tef seeds. Tef seeds inoculated with potential endophytes showed 100 % germination performance on 3 to 4 days after inoculation. An increase in mean shoot and roots length of the inoculated seeds were observed up to 3 and 2.6 cm respectively. Vigor index of seedling was measured from 460 to 520 on the last day of the experiment. These promising identified tef endophytic bacterial species or strains having PGP, biotic and abiotic stress tolerance properties could be candidate organisms for the development of microbial inoculants as single strain or consortia. This strategy would work towards solving the problem of over-utilizing chemical fertilizers, and reducing environmental pollution while increasing the yield and productivity of tef crops and other agricultural plants.

The signalling molecules serve as a fundamental requirement in plants and respond to various internal and external cues. Among several signalling molecules, the significance of gasotransmitters has been realized in several plant developmental and environmental constraints. The hydrogen sulfide (H2S) is a novel signalling molecule in higher plants and is involved in several physiological processes right from seed germination to flowering and fruit ripening. Moreover, H2S also assist plants in managing biotic and abiotic stresses, therefore serves as one of the imperative choice of chemical priming. Yet, the metabolism of H2S is not much explored and only appraisal study is made till date fromArabidopsis thaliana. Therefore, the present investigation explored the elucidation of H2S metabolism in crop plantSolanum lycopersicumL. Through in silico investigations the study demonstrated the participation of 29 proteins involved in H2S metabolism, which are mainly localized in cytosol, chl...

La produttività potenziale delle piante coltivate è fortemente limitata da condizioni ambientali limitanti (stress biotici e abiotici). Tra queste, la carenza idrica è uno dei fattori che maggiormente influenza la produttività sia in termini quantitativi che qualitativi. La tolleranza alla siccità, così come ad altre condizioni avverse, è un carattere poligenico: essa dipende, infatti, dall'espressione coordinata di interi set di geni comprendenti geni codificanti per proteine direttamente coinvolte nella protezione-riparo dai danni da stress (geni agenti a valle: deidrine, chaperonine, enzimi per la sintesi di osmoprotettivi e detossificanti, ecc.) e geni implicati nella regolazione dell'espressione (geni agenti a monte: fattori trascrizionali, chinasi, fosfatasi, ecc.). Al fine di comprendere le basi genetico-molecolari della tolleranza a tale condizione, negli ultimi anni, l'attenzione si è spostata dallo studio dei singoli geni a valle, a quello dei geni a monte nel tentativo di identificare i determinati genetici responsabili della percezione e trasmissione del segnale di stress e capaci quindi di attivare una risposta complessa e più efficace. Lo sviluppo di nuove tecniche ha permesso, inoltre, di spostare l'attenzione ad una visione d'insieme: è stato quindi possibile analizzare i cambiamenti globali determinati in una pianta da carenza idrica, a livello di trascrittoma, proteoma e metaboloma. Inoltre, gli approcci di genetica mirata, permettendo la variazione di espressione di singoli geni permette di determinarne la funzione. Infine, lo sviluppo di sistemi informatici sempre più sofisticati permette di integrare l'enorme mole di informazioni continuamente generata: l'insieme di questi nuovi approcci sta dando grande impulso all'identificazione dei geni maggiormente responsabili della tolleranza a stress, all'identificazione importanti QTL, allo sviluppo di valide strategie di ingegneria genetica o di MAS per ottenere piante con migliorata tolleranza. In questa review, sono riportati i più recenti risultati in campo internazionale sui succitati temi, riguardanti sia piante modello che piante di interesse agronomico. È stata rivolta particolare attenzione agli studi sui network genici coinvolti nella risposta a stress idrico (pathway ABA-dipendenti ed ABA-indipendenti), sugli approcci innovativi per identificare funzioni geniche importanti nel fenotipo di tolleranza (forward e reverse genetics), sulle strategie genetiche avanzate per ottenimento di genotipi con aumentata tolleranza (ingegneria genetica, MAS basati su QTL). Parole chiave: tolleranza a stress idrico, geni indotti da carenza idrica, regolazione dell'espressione genica, marker assisted breeding, QTL.

Defenses of direct and indirect means are used by plants in order to protect themselves from pest invasion. Direct defense entails biophysical, biochemical, molecular and nutritional barriers that have an impact on herbivores ability to feed grow and survive. Indirect defense entails the emission of mixture of volatile blends referred as Herbivore Induced Plant Volatiles (HIPVs) which attract the natural defenders of the insect pests. These defense-oriented tactics utilized by the plants are strengthened if they are given silicon (Si). Si is absorbed by plants as silicic acid, which they draw in as phytoliths to boost their physical defense. Upon a pest attack, silicon deposited in plant tissue is intensified. In addition, Si increases the protein activity and gene expression which are attributed towards inducing the plant defense and enhancing the building-up of secondary metabolites, hence activates molecular and biochemical defenses. Additionally, Si is essential for both direct and indirect defense mechanisms mediated by phytohormones. Silicon's role in insect defense is more obvious, but the practical applications related to crop protection studies have garnered less attention. This review focuses on the underlying mechanism of different forms of Si in strengthening host plant resistance against insect herbivores.