UC San Diego
Pseudomonas syringae Effector, AvrPto Alters Circadian Clock Function in Arabidopsis thaliana
- Author(s): Turkalj, Elena
- Advisor(s): Pruneda-Paz, Jose L
- et al.
An internal time keeping mechanism known as the circadian clock allows organisms to anticipate changes in the environment (Michael et al., 2003; Dodd, 2005). Environmental stressors have been shown to disrupt the circadian clock so it cannot accurately predict those changes. For example, a previous study revealed that a Pseudomonas Syringae infection altered the clock and led to a period lengthening phenotype (Li et al., 2018). The long period phenotype was not found to be mediated by defense responses but by a pathogen response (Li et al., 2018). P.syringae is known to secrete effectors to subdue defense responses, metabolism, and host degradation machinery but it has not been shown to modulate the circadian clock (Djamei et al., 2011; Mathieu et al., 2014). To better understand if effectors may be influencing the clock period, we explored if effectors may directly bind to core clock proteins in Arabidopsis. We found that a P.syringae effector, AvrPto directly binds to TOC1 and competitively inhibits the binding of a TOC1 regulator, ZTL. Transgenic Arabidopsis lines expressing AvrPto revealed a period lengthening suggesting that effectors have a role in modulating clock function. This study is the first to pinpoint a specific effector having a direct effect on the plant circadian clock.