Abstract

3rd Kenneth Sporne Lecture

An outstanding question is the extent to which independent evolutionary origins of the same morphological trait result from similar changes to genetic and developmental systems. To explore this question we have been evaluating the role of the floral meristem identity gene LEAFY (LFY) in three lineages of Brassicaceae (Idahoa, Leavenworthia, and Ionopsidium) that have transitioned from an ancestral inflorescence-flowering architecture to a derived rosette flowering architecture. In Ionopsidium LFY shows a distinct expression pattern in rosette flowering versus inflorescence flowering species, and transgenic experiments suggest that this is due to upstream trans-acting regulators. In Idahoa the two LFY genes show anomalous patterns of molecular evolution and alter plant architecture when introduced into an inflorescence flowering species, supporting the hypothesis that changes at the LFY loci contributed to the evolution of rosette flowering. In Leavenworthia the single LFY gene shows anomalous patterns of molecular evolution and has apparently coevolved with the TERMINAL FLOWER 1 gene to influence plant architecture. Overall these data, suggest that even among close relatives there may be several molecular paths to the same evolutionary outcome, but that these paths may all impinge the same small number of developmental regulators.

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