Physiology

Abstract

Sea beet is an ideal plant species for evolutionary ecology studies. The range of variation is very large among its populations for life cycle and several life-history traits, such as the proportion of dormant seeds, mean life span, age at maturity, flowering time, day length requirement and vernalization requirement for flowering. These traits follow latitudinal patterns in France, of which many correlate with ecological factors. The range of variation of these traits, their geographical patterns, heritability and the ecology have been studied.Alarge potential for a genetic change in day length sensitivity has been observed experimentally, and a substantial genetic change in the flowering date within two decades has been reported, probably in line with the recent climate change. Sea beet also displays a geographical variation for some reproductive traits, that is, self-incompatibility and male-sterility. Sea beet exhibits two specific characteristics in its mating system when compared with the other species of the section: it is self-incompatible and gynodioecious. Gynodioecy is under cytonuclear control, sterilizing factors being encoded by the mitochondrial genome. Recent advances on the molecular characterization of the different malesterilizing mitochondrial genomes found in beet are reported.