Inheritance of Rapid Cycling inBrassica rapaFast Plants: Dominance That Increases with Photoperiod

Abstract

Premise of research. The Wisconsin Fast Plants lines of Brassica rapa (RCBr) have been a useful model system for plant ecology, evolution, physiology, and development. However, inheritance of flowering time in the B. rapa Fast Plants has not been explored.Methodology. I used quantitative genetics to explore additive, dominant, and epistatic genetic components of between-line variance in flowering time and for genotype × photoperiod interaction effects in crosses between RCBr and naturalized Californian populations.Pivotal results. Strong directional dominance for rapid flowering was evident in the F1 and F2 generations. Evidence was equivocal for epistatic genetic variance between the RCBr and California parental types. The expression of additive genetic variance for flowering time in the naturalized California populations was not masked when combined with the RCBr genetic background. A strong genotype × photoperiod interaction was found; whereas flowering time for RCBr was unaffected by day length, flowe...