Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 20 mai 2010
Amphi 208 (Cœur d’Ecole) à 14h
Calcium-dependent protein kinases mediating calcium signaling in plant innate immunity
CNRS-Gif sur Yvette
Calcium is a ubiquitous second messenger in plant, that mediates complex responses to developmental stimuli as well as biotic and abiotic stresses. Calcium signals can be decoded by diverse calcium sensors including calcium-dependent protein kinases (CDPKs). Although their kinase activity has been involved in multiple signaling pathways, only few isoforms have been assigned a specific biological function. In plant innate immunity, the recognition of MAMPs (microbe-associated molecular patterns) such as flagellin (flg22), initiates convergent signaling pathways involving Ca2+ influxes, MAPK cascade activation, oxidative burst and transcriptional changes. Yet, how Ca2+signals are sensed and relayed into early MAMP signaling is unknown. Using a functional genomic screen and genome-wide gene expression profiling, we have showed that four CDPKs are critical for transcriptional reprogramming in plant innate immunity. Unexpectedly, CDPKs and MAPK cascades regulate at least four gene expression programs, either independently, in parallel or synergistically. While single cpkmutants do not exhibit overt phenotype, double, triple and quadruple cpk mutants display progressively diminished flg22-induced gene expression, oxidative burst and pathogen defence. All together, these results demonstrate key positive roles of specific CDPKs in initial MAMP signaling.
Contact : Tou Cheu Xiong