XVI International Botanical Congess

The phytochrome photosensory system is known to mediate adaptive responses to competition for sunlight. Although phytochrome genes are expressed in flowers, the potential role of the sensory system in floral morphogenesis remains uninvestigated. This study examines the effects of individual phytochromes and light-quality conditions on floral morphogenesis. Floral morphogenesis in wild-type and phy-deficient mutants of A. thaliana thaliana is compared. Responses of wild-type A. thaliana, Brassica rapa and Raphanus raphanus to light quality is studied. Mutants deficient in phytochromes A or B exhibited greater filament elongation than wild-type plants. Responses to light quality differed among the three Crucifer species. Because spatial positioning of stigmas and anthers can affect the likelihood of pollen deposition and removal, floral responses to light quality may affect reproductive assurance.