621 / 2019-04-24 15:58:39

Uncovering Time of Day Dependent Gene Regulation by the JA receptor, COI1

JA,hormonal crosstalk,SA,circadian

Plant Hormones > Plant Hormones

Plants, as sessile organisms, have evolved to coordinate spatial and temporal signals that allow them to anticipate a myriad of stresses. They optimize their chance of survival through intersecting hormonal networks that enable them to correctly amplify or dampen specific defense responses. To confer a properly timed defense output necessary for outcompeting a given attacker, phytohormone signaling programs such as of salicylic acid (SA) and jasmonate (JA), which can act antagonistically, need to be finely tuned. JA acts as a molecular glue coordinating JASMONATE-ZIM DOMAIN (JAZ) repressor protein recruitment by the JA receptor and F-Box protein CORONATINE-INSENSITIVE PROTEIN 1 (COI1), leading to the subsequent ubiquitination and degradation of the JAZs. The subsequent de-repression of transcription factors activates the JA response and can work to repress the SA response. Yet, much still remains to be elucidated about how hormonal signaling coordinates plant fitness. Interestingly, using next generation sequencing, we discovered that COI1 regulates expression of genes in a SA dependent cluster. The regulation of COI1 on the gene cluster is time-of-day dependent, under non-stressed conditions. Better understanding of how COI1 modulates this response will uncover novel, possibly JA-independent, roles of COI1 and help in our molecular understanding of how plants coordinate defense against pathogens.