PSC Distinguished Seminar Series
Title: Regulation of Cold Acclimation and Pathogen Immunity by Arabidopsis CAMTA Transcription Factors
Speaker: Prof. Michael Thomashow, University Distinguished Professor, MSU Foundation Professor, Michigan State University
Time: 10:00 am
Day/Date: December 3rd, 2018 (Monday)
Host PI: Prof. Jian-Kang Zhu
Venue: PSC Auditorium
Arabidopsis thaliana calmodulin-binding transcription factors CAMTA1, CAMTA2 and CAMTA3 function in an additive manner to regulate the expression of genes involved in cold acclimation and immunity against biotrophic and hemibiotrophic pathogens. In the case of cold acclimation, the CAMTA proteins rapidly induce genes in response to low temperature (4°C) that impart an increase in freezing tolerance. In the case of immunity, the CAMTA transcription factors act to repress the expression of genes involved in the biosynthesis of salicylic acid (SA) in healthy plants grown at moderate temperature (22°C). However, CAMTA-mediated repression of SA pathway genes is overcome in plants exposed to low temperature (4°C) for more than one week and in plants infected by pathogens. Our goal is to understand the mechanisms by which the CAMTA transcription factors act as inducers and repressors of gene expression and how their activities are regulated by both rapid-acting and slow-acting cold-signaling pathways. We have found that CAMTA3-mediated repression of SA pathway genes involves action of an N-terminal repression module (NRM) that acts independently of calmodulin (CaM) binding to the CaM-binding (CaMB) domain. In addition, mutational analysis has provided evidence that the repression activity of the NRM is suppressed by action of the IQ and CaMB calmodulin binding domains responding to signals generated in response to low temperature and pathogen infection. Our results indicate that current CAMTA3 structure-function models require revision and that regulation of CAMTA3 repression activity by low temperature and pathogen infection involves related mechanisms with distinct differences.
The seminar will be delivered in English.