XVI International Botanical Congess

To investigate the genetic basis of plasticity to maternal photoperiod, we examined two natural lines, Cal-0, a winter annual, and Tac-0, a spring annual, and their recombinant inbreds. We evaluated the effects of maternal photoperiod, offspring cold stratification, and photoperiod on post-germination traits. Cal responded to maternal photoperiod but not offspring cold, while Tac responded to cold but not maternal photoperiod. Responses of recombinant lines were significantly more variable than those of the parental lines, in both direction and degree. They displayed all possible combinations of plasticity: plasticity to neither, one, or both cues, indicating involvement of several genes. Response to maternal photoperiod depended strongly on offspring environment. Thus, potential to respond to selection on plasticity to maternal photoperiod may depend on the offspring environment.