The diversity of stomatal development regulation in <i>Callitriche</i> is related to the intrageneric diversity in lifestyles

Abstract

Significance Plant stomata are produced through divisions and differentiation of stem cells, termed meristemoids. During stomatal development, we see diverse patterns of meristemoid behavior among land plant lineages. However, both the ecological significance and the diversification processes of this diversity remain mostly unknown. Here we report that the ecologically diverse genus Callitriche shows unprecedented intrageneric diversity in meristemoid behavior. While meristemoids in terrestrial species of Callitriche undergo a series of asymmetric divisions before differentiation, those in amphibious species skip the divisions and directly differentiate into stomata. The simple shift in the expression times of two key transcription factors underlies these different patterns. This study provides important insights into the evolution and ecological significance of stomatal patterning.