Papers by Balakrishnan Prithiviraj
Marine Drugs, Jan 11, 2012
The effects of Tasco ® , a product made from the brown seaweed (Ascophyllum nodosum) were tested ... more The effects of Tasco ® , a product made from the brown seaweed (Ascophyllum nodosum) were tested for the ability to protect Caenorhabditis elegans against Pseudomonas aeruginosa infection. A water extract of Tasco ® (TWE) reduced P. aeruginosa inflicted mortality in the nematode. The TWE, at a concentration of 300 µg/mL, offered the maximum protection and induced the expression of innate immune response genes viz.; zk6.7 (Lypases), lys-1 (Lysozyme), spp-1 (Saponin like protein), f28d1.3 (Thaumatin like protein), t20g5.7 (Matridin SK domain protein), abf-1 (Antibacterial protein) and f38a1.5 (Lectin family protein). Further, TWE treatment also affected a number of virulence components of the P. aeuroginosa and reduced its secreted virulence factors such as lipase, proteases and toxic metabolites; hydrogen cyanide and pyocyanin. Decreased virulence factors were associated with a significant reduction in expression of regulatory genes involved in quorum sensing, lasI, lasR, rhlI and rhlR. In conclusion, the TWE-treatment protected the C. elegans against P. aeruginosa infection by a combination of effects on the innate immunity of the worms and direct effects on the bacterial quorum sensing and virulence factors.
Infection and Immunity, Sep 1, 2005
Salicylic acid (SA) is a phenolic metabolite produced by plants and is known to play an important... more Salicylic acid (SA) is a phenolic metabolite produced by plants and is known to play an important role in several physiological processes, such as the induction of plant defense responses against pathogen attack. Here, using the Arabidopsis thaliana-Pseudomonas aeruginosa pathosystem, we provide evidence that SA acts directly on the pathogen, down regulating fitness and virulence factor production of the bacteria. Pseudomonas aeruginosa PA14 showed reduced attachment and biofilm formation on the roots of the Arabidopsis mutants lox2 and cpr5-2, which produce elevated amounts of SA, as well as on wild-type Arabidopsis plants primed with exogenous SA, a treatment known to enhance endogenous SA concentration. Salicylic acid at a concentration that did not inhibit PA14 growth was sufficient to significantly affect the ability of the bacteria to attach and form biofilm communities on abiotic surfaces. Furthermore, SA down regulated three known virulence factors of PA14: pyocyanin, protease, and elastase. Interestingly, P. aeruginosa produced more pyocyanin when infiltrated into leaves of the Arabidopsis transgenic line NahG, which accumulates less SA than wild-type plants. This finding suggests that endogenous SA plays a role in down regulating the synthesis and secretion of pyocyanin in vivo. To further test if SA directly affects the virulence of P. aeruginosa, we used the Caenorhabiditis elegans-P. aeruginosa infection model. The addition of SA to P. aeruginosa lawns significantly diminished the bacterium's ability to kill the worms, without affecting the accumulation of bacteria inside the nematodes' guts, suggesting that SA negatively affects factors that influence the virulence of P. aeruginosa. We employed microarray technology to identify SA target genes. These analyses showed that SA treatment affected expression of 331 genes. It selectively repressed transcription of exoproteins and other virulence factors, while it had no effect on expression of housekeeping genes. Our results indicate that in addition to its role as a signal molecule in plant defense responses, SA works as an anti-infective compound by affecting the physiology of P. aeruginosa and ultimately attenuating its virulence.
Control of powdery mildew (Erysiphe pisi) of pea (Pisum sativum) by combined application of plant growth-promoting rhizobacteria and Neemazal
Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, 2000
... Authors Singh, UP; Prithiviraj, B.; Singh, KP; Sarma, BK Journal Zeitschrift für Pflanzenkran... more ... Authors Singh, UP; Prithiviraj, B.; Singh, KP; Sarma, BK Journal Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz 2000 Vol. ... different concentrations was tested under field conditions at the Vegetable Research Farm of Banaras Hindu University, Uttar Pradesh, India, during ...
Cellular Microbiology, Mar 1, 2005
Several bacteria that are pathogenic to animals also infect plants. Mechanistic studies have prov... more Several bacteria that are pathogenic to animals also infect plants. Mechanistic studies have proven that some human/animal pathogenic bacteria employ a similar subset of virulence determinants to elicit disease in animals, invertebrates and plants. Therefore, the results of plant infection studies are relevant to animal pathogenesis. This discovery has resulted in the development of convenient, cost-effective, and reliable plant infection models to study the molecular basis of infection by animal pathogens. Plant infection models provide a number of advantages in the study of animal pathogenesis. Using a plant model, mutations in animal pathogenic bacteria can easily be screened for putative virulence factors, a process which if done using existing animal infection models would be time-consuming and tedious. High-throughput screening of plants also provides the potential for unravelling the mechanisms by which plants resist animal pathogenic bacteria, and provides a means to discover novel therapeutic agents such as antibiotics and anti-infective compounds. In this review, we describe the developing technique of using plants as a model system to study Pseudomonas aeruginosa , Enterococcus faecalis and Staphylococcus aureus pathogenesis, and discuss ways to use this new technology against disease warfare and other types of bioterrorism.
Peronospora pisi spore load on different leaves and its effect on chlorophyll, nucleic acid, protein and phenol contents of pea leaves
Indian phytopathology, 1993
Peronospora pisi spore load on different nodal leaves and its effect on chlorophyll, protein, phe... more Peronospora pisi spore load on different nodal leaves and its effect on chlorophyll, protein, phenols and nucleic acid contents of pea leaves (cv. HUP 1) were studied. The maximum spore load (46 X 104 ) was observed on 18th nodal leaves at 23.51 per cent disease intensity. The chlorophyll, protein, phenols and nucleic acid content varied in the infected zone, healthy tissues near infection (0.5 cm away) and healthy leaves. Significant decrease in nucleic acids (RNA and DNA), phenols and chlorophyll was observed in the infected zone while total protein increased.
New Phytologist, Dec 21, 2006
• The flavonol (±)-catechin is an allelochemical produced by the invasive weed Centaurea maculosa... more • The flavonol (±)-catechin is an allelochemical produced by the invasive weed Centaurea maculosa (spotted knapweed). The full effects of (±)-catechin on plant communities in both the native and the introduced ranges of C. maculosa remain uncertain. • Here, by supplementing plant growth media with (±)-catechin, we showed that low (±)-catechin concentrations may induce growth and defense responses in neighboring plants. Doses of the allelochemical lower than the minimum inhibitory concentration (MIC) induced growth in Arabidopsis thaliana ; plants treated with 25 µg ml − 1 (±)-catechin accumulated more than twice the biomass of untreated control plants. Further, pretreatment of A. thaliana roots with low concentrations of (±)-catechin induced resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 in A. thaliana leaves. • Low doses of (±)-catechin resulted in moderate increases in reactive oxygen species (ROS) in the meristems of treated plants, which may have loosened the cell walls and thus increased growth. Experiments with A. thaliana mutants indicated that (±)-catechin induces pathogen resistance by up-regulating defense genes via the salicylic acid (SA)/nonexpressor of pathogenesis related protein 1 (NPR1)dependent pathway. • Our results suggest that the growth and defense-inducing effects of (±)-catechin are concentration dependent, as (±)-catechin at higher concentrations is phytotoxic, thus suggesting the potential for hormesis to occur in nature.
Development ofErysiphe pisi(Powdery Mildew) on Normal and Albino Mutants of Pea (Pisum sativumL.)
Journal of Phytopathology, Dec 1, 2000
Early development of Erysiphe pisi (powdery mildew) was studied on normal peas (with chlorophyll)... more Early development of Erysiphe pisi (powdery mildew) was studied on normal peas (with chlorophyll), natural albino mutants (without chlorophyll) and on chimeric leaves of pea induced by ethyl methane sulphonate (EMS) under different light exposures. Different light regimes [continuous light; continuous darkness; short day (8 h light/16 h darkness); long day (16 h light/8 h darkness)] did not influence the early development of E. pisi on pea leaves. However, under continuous darkness a lower number of haustoria was observed in comparison with other treatments. Erysiphe pisi failed to develop on naturally developed complete albino leaves as well as on the albino parts of chimeric leaves induced by EMS treatment. A lesser number of appressoria and haustoria was observed on albino leaves. Results suggest that the presence of some nondiffusable chemical(s) in normal leaves of pea is essential for the establishment of successful biotrophy.
Folia Microbiologica, Aug 1, 1998
3-(2-Pyridyl)-3-iminoisatin, 1-piperidinomethyl-3-(2-pyridyl)-3-iminoisatin, and 1-acetyl-3-(2-py... more 3-(2-Pyridyl)-3-iminoisatin, 1-piperidinomethyl-3-(2-pyridyl)-3-iminoisatin, and 1-acetyl-3-(2-pyridyl)-3-iminoisatin affect spore germination of Alternaria alternata, A. carthemi, Curvularia lunata, Fusarium oxysporum f.sp. ciceri and 17. udum and influence the development of powdery mildew (Erysiphe pisi) on pea under glasshouse condition as well as conidial germination of E. pisi on excised pea leaves. Spore germination was inhibited in the sequence 1-acetyl-3-(2-pyridyt)-3-iminoisatin > 1-piperidinomethyl-3-(2-pyridyi)-3-iminoisatin > 3-(2-pyridyl)-3-iminoisatin followed the order accordingly. The powdery mildew development and conidial germination of E.pisi 1-piperidinomethyl-3-(2-pyridyl)-3-iminoisatin > 1-acetyl-3-(2-pyridyl)-3-iminoisatin > 3-(2-pyridyl)-3-iminoisatin. The chemicals were compared with commonly used antifungal fungicides.
Scientific Reports, 2020
Microbial inoculation in drought challenged rice triggered multipronged steps at enzymatic, non-e... more Microbial inoculation in drought challenged rice triggered multipronged steps at enzymatic, non-enzymatic and gene expression level. These multifarious modulations in plants were related to stress tolerance mechanisms. Drought suppressed growth of rice plants but inoculation withTrichoderma,Pseudomonasand their combination minimized the impact of watering regime. InducedPALgene expression and enzyme activity due to microbial inoculation led to increased accumulation of polyphenolics in plants. Enhanced antioxidant concentration of polyphenolics from microbe inoculated and drought challenged plants showed substantially high values of DPPH, ABTS, Fe-ion reducing power and Fe-ion chelation activity, which established the role of polyphenolic extract as free radical scavengers. Activation of superoxide dismutase that catalyzes superoxide (O2−) and leads to the accumulation of H2O2was linked with the hypersensitive cell death response in leaves. Microbial inoculation in plants enhanced a...
The effect of verapamil (a plasma membrane Ca2+ channel blocker), ruthenium red (RR) (an organell... more The effect of verapamil (a plasma membrane Ca2+ channel blocker), ruthenium red (RR) (an organelle Ca2+ channel blocker) and chlorpromazine, a calmodulin (CaM) antagonist was seen on the spore germination of some plant pathogenic fungi. The Ca2+ channel blockers and CaM differentially affected spore germination. The inhibitory effect of Ca2+ reverted by increasing the external Ca 2 + concentration. Fungi sensitive to verapamil were relatively resistant to RR and vice-versa. Washing spores with ethylene diamine tetra acetic acid (EDT A) increased sensitivity to Ca2+ channel blocker. Results suggest an interplay of cell wall and organelle Ca2+ in triggering spore germination process.
Plants, Mar 7, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
BMC Plant Biology, Jul 29, 2013
Background: Plants have evolved an array of constitutive and inducible defense strategies to rest... more Background: Plants have evolved an array of constitutive and inducible defense strategies to restrict pathogen ingress. However, some pathogens still manage to invade plants and impair growth and productivity. Previous studies have revealed several key regulators of defense responses, and efforts have been made to use this information to develop disease resistant crop plants. These efforts are often hampered by the complexity of defense signaling pathways. To further elucidate the complexity of defense responses, we screened a population of T-DNA mutants in Colombia-0 background that displayed altered defense responses to virulent Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Results: In this study, we demonstrated that the Arabidopsis Purple Acid Phosphatse5 (PAP5) gene, induced under prolonged phosphate (Pi) starvation, is required for maintaining basal resistance to certain pathogens. The expression of PAP5 was distinctly induced only under prolonged Pi starvation and during the early stage of Pst DC3000 infection (6 h.p.i). T-DNA tagged mutant pap5 displayed enhanced susceptibility to the virulent bacterial pathogen Pst DC3000. The pap5 mutation greatly reduced the expression of pathogen inducible gene PR1 compared to wild-type plants. Similarly, other defense related genes including ICS1 and PDF1.2 were impaired in pap5 plants. Moreover, application of BTH (an analog of SA) restored PR1 expression in pap5 plants. Conclusion: Taken together, our results demonstrate the requirement of PAP5 for maintaining basal resistance against Pst DC3000. Furthermore, our results provide evidence that PAP5 acts upstream of SA accumulation to regulate the expression of other defense responsive genes. We also provide the first experimental evidence indicating the role PAP5 in plant defense responses.
Plant Physiology, Sep 26, 2017
XBAT35 belongs to a subfamily of Arabidopsis (Arabidopsis thaliana) RING-type E3s that are simila... more XBAT35 belongs to a subfamily of Arabidopsis (Arabidopsis thaliana) RING-type E3s that are similar in domain architecture to the rice (Oryza sativa) XA21 Binding Protein3, a defense protein. The XBAT35 transcript undergoes alternative splicing to produce two protein isoforms, XBAT35.1 and XBAT35.2. Here, we demonstrate that XBAT35.2 localizes predominantly to the Golgi and is involved in cell death induction and pathogen response. XBAT35.2, but not XBAT35.1, was found to trigger cell death when overexpressed in tobacco (Nicotiana benthamiana) leaves and does so in a manner that requires its RING domain. Loss of XBAT35 gene function disrupts the plant's ability to defend against pathogen attack, whereas overexpression of XBAT35.2 enhances resistance to pathogens. XBAT35.2 was found to be unstable and promotes its own degradation, suggesting self-regulation. Inoculation with virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae pv tomato DC3000 results in a drastic reduction in the levels of ubiquitinated XBAT35.2 and an increase in the abundance of the E3. This implies that pathogen infection prohibits XBAT35.2 self-regulation and stabilizes the E3. In agreement with a role in defending against pathogens, XBAT35.2 interacts with defense-related Accelerated Cell Death11 (ACD11) in planta and promotes the proteasome-dependent turnover of ACD11 in cell-free degradation assays. In accordance with regulation by a stabilized XBAT35.2, the levels of ubiquitinated ACD11 increased considerably, and the abundance of ACD11 was reduced following pathogen infection. In addition, treatment of transgenic seedlings with a proteasome inhibitor results in the accumulation of ACD11, confirming proteasome-dependent degradation. Collectively, these results highlight a novel role for XBAT35.2 in cell death induction and defense against pathogens.
Frontiers in sustainable food systems, Apr 26, 2022
Neuroprotective potential of flavonoid rich Ascophyllum nodosum (FRAN) fraction from the brown seaweed on an Aβ42 induced Alzheimer's model of Drosophila
Phytomedicine, 2021
In Alzheimer Disease (AD) pathogenesis, aggregation of Aβ42 fibrils strongly correlates with memo... more In Alzheimer Disease (AD) pathogenesis, aggregation of Aβ42 fibrils strongly correlates with memory dysfunction and neurotoxicity. Till date, no promising cures for AD. Report shows that flavonoids contributed anti-oxidant, anti-cancer and neuroprotection activity by regulating the mitochondrial machinery. Here, we first report the identification of flavonoids from Ascophyllum nodosum as having the ability to dissolve Aβ42 fibrils in an AD model of Drosophila. FRAN could be superior anti-AD agents for neuroprotection, their underlying mechanism and how they collectively halted amyloidogenesis is currently being investigated. This study aimed to investigate the neuroprotective role of FRAN in the Aβ42 expressing AD model of Drosophila. Drosophila stocks: OregonR+, ey-GAL4/CyO, elavc155-GAL4, UAS-mitoGFP, UAS-mcherry.mito.OMM, UAS-Aβ42/CyO were used, cultured at 28±1 °C in a BOD incubator. Ascophyllum extract rich in flavonoids as revealed by LC-MS study and employed against the AD flies. The validation of Aβ42 expression was done by immunostaining and q-RT PCR. The eye roughness of AD flies was scored in a dose-dependent manner. Further, In vivo and in silico studies of FRAN extract was executed against Aβ42 induced neurotoxicity. In order to determine the most effective lethal dose of FRAN extract concentration 1, 2, 5, 10 mg/ml were screened using OregonR+flies. Extract 1 and 2 mg/ml did not show any lethality. Hence, extract 2 mg/ml was employed on AD flies and a ≥ 50% rescue in the eye phenotype was observed using SEM images. This dose had a strong effect on cell apoptosis, viability, longevity, mitochondrial dysfunction and oxidative stress by regulating mitochondrial dynamic markers in comparable to control. Extract also scavenging free radicals in order to maintain in situ cellular ROS and prevent Aβ42-induced neurotoxicity in vivo and in silico. Hence, we suggest its great potential as a future therapeutic agent for AD treatment. In conclusion, FRAN extract rich in flavonoids as having largest neuroprotective activity against Aβ42 aggregation in eye tissue of Drosophila. Extract shows strong effect against Aβ42-induced neurotoxicity by altering the various cellular and molecular events. So, it could be considered as strong anti-AD agents for neuroprotection.
Crop Protection, 2020
Botrytis blossom blight is an important disease of wild blueberries in Canada that causes over 20... more Botrytis blossom blight is an important disease of wild blueberries in Canada that causes over 20% yield losses annually. Four trials (2 in each year) were set up in 2015 and 2016 to investigate the efficacy of biofungicides against Botrytis blossom blight in wild blueberry. Botector®, Fracture® and Serenade MAX® were evaluated alone and in rotation with Switch® and compared with a standard control program (Fontelis®, Switch®, and Pristine®). Three applications of each biofungicide were done for stand-alone treatment, and each rotated with Switch® as combined treatment. Fungicides were applied at 7-10-day intervals starting from pre-anthesis, white tip stage. Botector®, Fracture® and Serenade MAX® rotation with Switch® suppressed Botrytis blossom blight by over 65% and 60% less disease incidence and severity compared to the untreated control. Significant disease suppression was observed in stand-alone application of Botector®, Fracture® and Serenade MAX® in 2016 whereas they were not effective in 2015. The rotation of Fracture® and Serenade MAX® with Switch®, and stand-alone Serenade MAX® resulted in increased harvestable berry yield. The results suggest that the use of biofungicides in tandem with conventional fungicides in an integrated disease management program, can adequately suppress Botrytis blossom blights.
Variability in sclerotial morpholopgy in Sclerotium rolfsii: SEM and isozyme studies
Plants, Jan 3, 2023
Report of Clonostachys rosea as a Mycoparasite on Sclerotinia sclerotiorum Causing Head Rot of
Seaweeds for plant disease management: current research advances and future perspectives
Phytoparasitica
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Papers by Balakrishnan Prithiviraj