Pleiotropy in the environmental regulation of germination and flowering

KATHLEEN DONOHUE; GABRIELA A AUGE; LOGAN K BLAIR

Beijing

Simposio; 37th New Phytologist Symposium: Plant Developmental Evolution; 2016

New Phytologist Trust

Pleiotropy occurs when one gene regulates more than one trait, and it can be a strong constraint on the adaptive evolution of trait  combinations. In many organisms, several major developmentaltransitions between life stages are regulated by seasonal environmental factors, and the appropriate coordination of developmental transitions across the lifecycle is necessary to express adaptive life-history schedules. Many life stages may be sensitive to the same environmental factors, but they must respond to them differently. How do multiple life stages use the same environmental inputs to regulate their independent developmental transitions in a manner that results in adaptive life-history expression? We examined pleiotropy between the environmental regulation of two important life-stage transitions in plants: seed germination and the transition to reproduction. We tested whether genes known to regulate flowering responses to environmental cues also regulate seed germination in Arabidopsis thaliana. We found extensive pleiotropy between flowering and germination regulation. First, the major flowering gene Flowering Locus C (FLC) contributes to seedgermination, such that increased FLC activity is associated with increased germination. Regarding the vernalization pathway, both promoters and repressors of FLC expression also contribute togermination, but in ways that are not predicted based on their function in the flowering pathway. Likewise, genes in the autonomous pathway and the photoperiod pathway contribute to germination, but in ways that are not always predictable from their function in the flowering pathway. In sum, genes in the vernalization flowering pathway, the autonomous flowering pathway, and the photoperiod flowering pathway all contribute to seed germination. The combined results suggest that, although the same environmental-sensing pathways are used to regulate these twodevelopmental transitions, the function of genes in those pathways is not always concordant across germination and flowering. Despite pleiotropy, these two developmental transitions appear to be able to be regulated independently to a great degree.