A mechanistic model of stamen filament development that may contribute to mating system evolution in Brassicaceae

LUCERO LE; GASTALDI V; GONZALEZ DH

Beijing

Simposio; 37th New Phytologist Symposium Plant developmental evolution; 2016

New Phytologist

The model species Arabidopsis thaliana has the particular ability to self-pollinate before floweropening. This mating system known as cleistogamy is highly rare among Angiosperms. The molecularevolutionary mechanisms leading to cleistogamy are far from being elucidated. In Arabidopsis,around stage 12 of flower development, stamen filaments acquire their full length reaching thestigmas at the top of the gynoecium in a highly synchronized fashion. Through a functional geneticapproach conducted in Arabidopsis, we determined that members of the TCP transcription factorfamily modulate the elongation of stamen filaments. To do so, TCP factors regulate genes involved inauxin homeostasis, which is the only phytohormone linked to cleistogamy. At the same time, wefound that a KNOX transcription factor represses stamen filament elongation acting upstream of TCPfactors. We also observed the presence of two adjacent KNOX sites in the promoter of one of theTCP genes, suggesting a direct repression mechanism. Modifications found in the promoter regionsof putative orthologues of this TCP gene in other Brassicaceae species suggest that this pathway maydiffer in the family and this may be related to mating system evolution.