CONICET | Buscador de Institutos y Recursos Humanos

In an ever-changing world, possessing the capability to adapt and even predict daily and seasonal environmental changes presents a valuable feature for living organisms. Subsequently, in most organisms multiple physiological and developmental processes are driven by an internal timekeeping mechanism known as the circadian clock, which accurately tuning contributes to an enhanced fitness. In plants, the endogenous biological clock regulates multiple processes, and in turn, several clock regulated signaling pathways feedback to control clock function. Given that plants do not have any specialized immune cells, each individual cell must regulate and balance the high energy consuming stress responses with other cellular functions, such as growth. The circadian clock has been shown to modulate plant immunity and the role of several clock genes in the control of biotic stress responses has been addressed, but whether plant-pathogen interactions modulate clock function is still unclear. In the current investigation, we found that an enhanced disease susceptibility (eds) mutant displayed alterations in circadian rhythms and clock associated responses. Simultaneously, we found that an infection with Pseudomonas syringae strongly alters the expression of most core clock genes, as early as 1h post-infection in wild type (wt) plants and that this effect was attenuated in the eds mutant. Furthermore, we identified new clock mutants that turned out to be more susceptible to Pseudomonas syringae infection. Thus, these results comprehend a novel example of the relevance regarding correct circadian function in defense responses and reinforce the idea of strong crosstalk between biotic stress stimulus and the Arabidopsis circadian clock.