XVI International Botanical Congess

Structural features of the pea compound leaf are affected by three well-defined genes. Either singly or in combination, they specify five distinct pinna types. Using simple genetics, classical criteria for establishing homology, SEM of leaf development, and pinna histology, the phenotypes of the afila (af), tendril-less (tl), and tendrilled acacia (unitac)/unifoliata (uni) mutants are compared to that of wild-type plants and the roles of the Af, Tl and Uni genes are deduced. The leaf blade consists of three inherent regions: proximal, distal and terminal. All three genes modify leaf form by altering the timing of events during leaf development. In addition, these genes affect most aspects of leaf morphology (pinna pair number, pinna, petiole and leaf lengths, pinna branching), histology and characteristics of shoot ontogeny (number of nodes, flowering, leaf heteroblasty).