Browsing by Author "Bhardwaj, Vaibhav"

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    Open Access
    Defence responses of Arabidopsis thaliana to infection by Pseudomonas syringae are regulated by the circadian clock
    (Public Library of Science, 2011) Bhardwaj, Vaibhav; Meier, Stuart; Petersen, Lindsay N; Ingle, Robert A; Roden, Laura C
    The circadian clock allows plants to anticipate predictable daily changes in abiotic stimuli, such as light; however, whether the clock similarly allows plants to anticipate interactions with other organisms is unknown. Here we show that Arabidopsis thaliana (Arabidopsis) has circadian clock-mediated variation in resistance to the virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000 ( Pst DC3000), with plants being least susceptible to infection in the subjective morning. We suggest that the increased resistance to Pst DC3000 observed in the morning in Col-0 plants results from clock-mediated modulation of pathogen associated molecular pattern (PAMP)-triggered immunity. Analysis of publicly available microarray data revealed that a large number of Arabidopsis defence-related genes showed both diurnal- and circadian-regulation, including genes involved in the perception of the PAMP flagellin which exhibit a peak in expression in the morning. Accordingly, we observed that PAMP-triggered callose deposition was significantly higher in wild-type plants inoculated with Pst DC3000 hrpA in the subjective morning than in the evening, while no such temporal difference was evident in arrhythmic plants. Our results suggest that PAMP-triggered immune responses are modulated by the circadian clock and that temporal regulation allows plants to anticipate and respond more effectively to pathogen challenges in the daytime.
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    Open Access
    Keeping time on the plant-pathogen arms race : a role for the plant circadian clock in immune response
    (2011) Bhardwaj, Vaibhav; Roden, Laura; Ingle, Robert
    In this study, Arabidopsis thaliana (Arabidopsis) in the Columbia-0 (Col-0) background showed time-of-day variation in susceptibility to the plant-pathogen Pseudomonas syringae DC3000 pathovar tomato (P. syringae DC3000) when infected under constant light and temperature conditions. Wild type plants showed least susceptibility at circadian time (CT) 26 and 50, which correspond to "subjective" morning. Plants were most susceptible when infected at CT42 and CT66, "subjective" night.