Plant Responses to Combined Drought and Pathogen Infection: Current Understanding on the Role of Phytohormones
Springer eBooks, 2017
Plants under natural conditions encounter a number of abiotic and biotic stresses often being inf... more Plants under natural conditions encounter a number of abiotic and biotic stresses often being inflicted simultaneously. Plant responses to a stress are governed by intricate network of the hormone signaling pathways. Abscisic acid (ABA) forms the major component of the plant response to drought and cold stress. Salicylic acid (SA), jasmonic acid (JA), and ethylene act as key regulators of plant response to pathogen infection. In fact, the extensive cross talk among the different hormone-mediated signaling pathways determines plant response to a particular stress. A large number of studies focus on hormone signaling under individual drought and pathogen stresses and the cross talk between the two stress responses. However, owing to the relatively few studies on combined drought and pathogen stresses, our understanding of phytohormonal signaling under combined stress is still obscure. Recent studies on combined drought and pathogen infection indicate that plants when simultaneously exposed to the two stresses often exhibit a transcriptional and metabolic response different from that exhibited under single stress conditions. This is also applicable to the phytohormonal signaling. The nature, time, and severity of the two stresses in combination modulate hormonal concentrations as well as the hormone signal transduction pathways involved. In this chapter, we provide a compendious description of the role of the three major hormones, namely, ABA, SA, and JA, in combined drought and pathogen infection. A brief description of the role of auxins, cytokinins, and gibberellins has also been provided. Taking leads from few studies, we have discussed the potential role of hormones in conferring combined drought and pathogen stress tolerance to plants. We also briefly discussed the effect of different “stress elicitors” on hormone signaling.
Global warming leads to the concurrence of a number of abiotic and biotic stresses, thus affectin... more Global warming leads to the concurrence of a number of abiotic and biotic stresses, thus affecting agricultural productivity. Occurrence of abiotic stresses can alter plant-pest interactions by enhancing host plant susceptibility to pathogenic organisms, insects, and by reducing competitive ability with weeds. On the contrary, some pests may alter plant response to abiotic stress factors. Therefore, systematic studies are pivotal to understand the effect of concurrent abiotic and biotic stress conditions on crop productivity. However, to date, a collective database on the occurrence of various stress combinations in agriculturally prominent areas is not available. This review attempts to assemble published information on this topic, with a particular focus on the impact of combined drought and pathogen stresses on crop productivity. In doing so, this review highlights some agriculturally important morpho-physiological traits that can be utilized to identify genotypes with combined stress tolerance. In addition, this review outlines potential role of recent genomic tools in deciphering combined stress tolerance in plants. This review will, therefore, be helpful for agronomists and field pathologists in assessing the impact of the interactions between drought and plant-pathogens on crop performance. Further, the review will be helpful for physiologists and molecular biologists to design agronomically relevant strategies for the development of broad spectrum stress tolerant crops.
Climate change has led to an increased number of abiotic and biotic stresses, and the plants expe... more Climate change has led to an increased number of abiotic and biotic stresses, and the plants experience these stresses simultaneously. Abiotic stresses like drought, heat, and salinity greatly influence plant-pathogen interaction when co-occurring with the biotic stressors. Recent studies have shown that combined stresses induce unique physiological and molecular responses, which involve rewiring of the hormonal pathways, accumulation of various metabolites and induction or suppression of immunity genes in plants. The net impact of the interaction, which depends on a multitude of factors, thus, modulates the effect of biotic stressors on plants by either increasing or decreasing plants susceptibility towards them. The present review aims to provide an overview of the current knowledge on the biotic and abiotic stress interactions in plants. We have discussed the role of drought, salt, and heat stress in influencing pathogen infection in plants in brief. Plants responses to the three types of combined stresses are compared to decipher the common and unique plant responses to these stresses.
Abiotic stressors such as drought and heat predispose chickpea plants to pathogens of key importa... more Abiotic stressors such as drought and heat predispose chickpea plants to pathogens of key importance leading to significant crop loss under field conditions. In this study, we have investigated the influence of drought and high temperature on the incidence and severity of dry root rot disease (caused by Macrophomina phaseolina) in chickpea, under extensive on- and off-season field trials and greenhouse conditions. We explored the association between drought tolerance and dry root rot resistance in two chickpea genotypes, ICC 4958 and JG 62, with contrasting resistance to dry root rot. In addition, we extensively analyzed various patho-morphological and root architecture traits altered by combined stresses under field and greenhouse conditions in these genotypes. We further observed the role of edaphic factors in dry root rot incidence under field conditions. Altogether, our results suggest a strong negative correlation between the plant water relations and dry root rot severity in c...
With the increasing understanding of fundamentals of gene silencing pathways in plants, various t... more With the increasing understanding of fundamentals of gene silencing pathways in plants, various tools and techniques for downregulating the expression of a target gene have been developed across multiple plant species. This chapter provides an insight into the molecular mechanisms of gene silencing and highlights the advancements in various gene silencing approaches. The prominent aspects of different gene silencing methods, their advantages and disadvantages have been discussed. A succinct discussion on the newly emerged microRNA-based technologies like microRNA-induced gene silencing (MIGS) and microRNA-mediated virus-induced gene silencing (MIR-VIGS) are also presented. We have also discussed the gene-editing system like CRISPR-Cas. The prominent bottlenecks in gene silencing methods are the off-target effects and lack of universal applicability. However, the tremendous growth in understanding of this field reflects the potentials for improvements in the currently available approaches and the development of new widely applicable methods for easy, fast, and efficient functional characterization of plant genes.
Stress Combinations and their Interactions in Plants Database (SCIPDb): A one-stop resource for understanding combined stress responses in plants
ABSTRACTWe have developedStressCombinations and theirInteractions inPlantsDatabase (SCIPDb;http:/... more ABSTRACTWe have developedStressCombinations and theirInteractions inPlantsDatabase (SCIPDb;http://www.nipgr.ac.in/scipdb.php), a compendium and interactive platform offering information on both morpho-physio-biochemical (phenome) and molecular (transcriptome) responses of plants to different combinations of stresses. To delineate the effects of various stress combinations/categories on yield in major agricultural crops, global phenome data from 939 studies was analyzed and results showed that yield was affected to the greatest extent under the abiotic–abiotic stress category, followed by the biotic–biotic and abiotic–biotic stress categories. In the abiotic–abiotic stress category, drought–heat, heat–salinity, and ozone–UV are the major stress combinations causing high yield loss in barley, wheat, soybean, and quinoa crops. In the abiotic–biotic stress category, the salinity–weed stress combination causes highest yield loss in rice crop. In the biotic–biotic stress category, the nem...
The imposition of environmental stresses on plants brings about disturbance in their metabolism t... more The imposition of environmental stresses on plants brings about disturbance in their metabolism thereby negatively affecting their growth and development and leading to reduction in the productivity. One of the manifestations of different abiotic and biotic stress conditions in plants is the enhanced production of reactive oxygen species (ROS) which can be hazardous to cells. Therefore, in order to protect themselves against toxic ROS, plant cells employ the anti-oxidant defense system. The ascorbate-glutathione pathway (Halliwell-Asada cycle) is an indispensible component of the ROS homeostasis mechanism of plants. This pathway entails the antioxidant metabolites: ascorbate, glutathione and NADPH along with the enzymes linking them. The ascorbate-glutathione pathway is functional in different subcellular compartments and all the enzymes of this pathway exist as multiple isoforms. The expression of different isoforms of the enzymes of ascorbate-glutathione pathway is developmentally as well as spatially regulated. Moreover, various abiotic and biotic stress conditions modulate the expression of the enzyme-isoforms differently. It is the intricate regulation of expression of different isoforms of the ascorbate-glutathione pathway enzymes that helps in the maintenance of redox balance in plants under various abiotic and biotic stress conditions. The present review provides an insight into the gene families of the ascorbate-glutathione pathway, shedding light on their role in different abiotic and biotic stress conditions as well as in the growth and development of plants.
Global warming leads to the concurrence of a number of abiotic and biotic stresses, thus affectin... more Global warming leads to the concurrence of a number of abiotic and biotic stresses, thus affecting agricultural productivity. Occurrence of abiotic stresses can alter plant-pest interactions by enhancing host plant susceptibility to pathogenic organisms, insects, and by reducing competitive ability with weeds. On the contrary, some pests may alter plant response to abiotic stress factors. Therefore, systematic studies are pivotal to understand the effect of concurrent abiotic and biotic stress conditions on crop productivity. However, to date, a collective database on the occurrence of various stress combinations in agriculturally prominent areas is not available. This review attempts to assemble published information on this topic, with a particular focus on the impact of combined drought and pathogen stresses on crop productivity. In doing so, this review highlights some agriculturally important morpho-physiological traits that can be utilized to identify genotypes with combined s...
Plant Responses to Combined Drought and Pathogen Infection: Current Understanding on the Role of Phytohormones
Plant Tolerance to Individual and Concurrent Stresses, 2017
Plants under natural conditions encounter a number of abiotic and biotic stresses often being inf... more Plants under natural conditions encounter a number of abiotic and biotic stresses often being inflicted simultaneously. Plant responses to a stress are governed by intricate network of the hormone signaling pathways. Abscisic acid (ABA) forms the major component of the plant response to drought and cold stress. Salicylic acid (SA), jasmonic acid (JA), and ethylene act as key regulators of plant response to pathogen infection. In fact, the extensive cross talk among the different hormone-mediated signaling pathways determines plant response to a particular stress. A large number of studies focus on hormone signaling under individual drought and pathogen stresses and the cross talk between the two stress responses. However, owing to the relatively few studies on combined drought and pathogen stresses, our understanding of phytohormonal signaling under combined stress is still obscure. Recent studies on combined drought and pathogen infection indicate that plants when simultaneously exposed to the two stresses often exhibit a transcriptional and metabolic response different from that exhibited under single stress conditions. This is also applicable to the phytohormonal signaling. The nature, time, and severity of the two stresses in combination modulate hormonal concentrations as well as the hormone signal transduction pathways involved. In this chapter, we provide a compendious description of the role of the three major hormones, namely, ABA, SA, and JA, in combined drought and pathogen infection. A brief description of the role of auxins, cytokinins, and gibberellins has also been provided. Taking leads from few studies, we have discussed the potential role of hormones in conferring combined drought and pathogen stress tolerance to plants. We also briefly discussed the effect of different “stress elicitors” on hormone signaling.
Tailored Responses to Simultaneous Drought Stress and Pathogen Infection in Plants
Drought Stress Tolerance in Plants, Vol 1, 2016
Under field conditions plants are often challenged by combination of biotic and abiotic stressors... more Under field conditions plants are often challenged by combination of biotic and abiotic stressors and they severely affect crop productivity. An increasing number of studies suggest that plants “tailor” their adaptation strategies to combat simultaneously occurring stresses. The stress combat strategies of plants are customized according to the stress combination and vary with the intensity and timing of the stresses involved. While some of the responses seen under combined stress are commonly instigated by individual stresses, some other are uniquely triggered under combined stress. Since some responses are unique only to the combined stress, the outcome of a stress interaction cannot be completely predicted using results from individual stress studies. In this chapter, the effects of combinatorial drought stress and pathogen infection on plants are discussed with an emphasis on the molecular and physiological mechanisms that underpin how plants tolerate simultaneously occurring stresses. We also highlight the complexity involved in the responses of plants to multiple stresses and underscore the importance of studying plant stressors in combination.
Impact of Concurrent Drought Stress and Pathogen Infection on Plants
Combined Stresses in Plants, 2014
Concurrent abiotic and biotic stress situations greatly limit the crop productivity. The global c... more Concurrent abiotic and biotic stress situations greatly limit the crop productivity. The global climate change is predicted to bring forth the frequent incidences of concurrent stresses, predominantly drought and pathogen infections. Thus, understanding the impact of drought on plant–pathogen interaction is important. In this chapter, we review the recent studies that focus on the effect of concurrent drought and pathogen infection on plants. These studies indicate that concurrent stress conditions lead to the activation of unique combat pathways that are otherwise not elicited under independent stresses. Plant responses, thus, seem to be adaptively tailored for combating the combined stresses. Here, we focus on the impact of drought stress on plant–pathogen relations and highlight the different ways by which plant–pathogen interactions are modulated at physiological and molecular level. Various studies reviewed in this chapter show that the stress combinations should be considered as a “unique stress” and a better understanding of plant responses to these conditions is needed. Therefore, we propose that further efforts should be directed to identify the potential pathways conferring concurrent stress tolerance.
Climate change has led to an increased number of abiotic and biotic stresses, and the plants expe... more Climate change has led to an increased number of abiotic and biotic stresses, and the plants experience these stresses simultaneously. Abiotic stresses like drought, heat, and salinity greatly influence plant-pathogen interaction when co-occurring with the biotic stressors. Recent studies have shown that combined stresses induce unique physiological and molecular responses, which involve rewiring of the hormonal pathways, accumulation of various metabolites and induction or suppression of immunity genes in plants. The net impact of the interaction, which depends on a multitude of factors, thus, modulates the effect of biotic stressors on plants by either increasing or decreasing plants susceptibility towards them. The present review aims to provide an overview of the current knowledge on the biotic and abiotic stress interactions in plants. We have discussed the role of drought, salt, and heat stress in influencing pathogen infection in plants in brief. Plants responses to the three types of combined stresses are compared to decipher the common and unique plant responses to these stresses.
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