Pea compound leaf architecture is regulated by interactions among the genes UNIFOLIATA, COCHLEATA, AFILA, and TENDRIL-LESS

The compound leaf primordium of pea represents a marginal blastozone that i nitiates organ primordia, in an acropetal manner, from its growing distal r egion. The UNIFOLIATA (UNI) gene is important in marginal blastozone mainte nance because loss or reduction of its function results in uni mutant leave s of reduced complexity. In this study, we show that UNI is expressed in th e leaf blastozone over the period in which organ primordia are initiated an d is downregulated at the time of leaf primordium determination. Prolonged UNI expression was associated with increased blastozone activity in the com plex leaves of afila (af), cochleata (coch), and afila tendril-less (af tl) mutant plants. Our analysis suggests that UNI expression is negatively reg ulated by COCH in stipule primordia, by AF in proximal leaflet primordia, a nd by AF and TL in distal and terminal tendril primordia. We propose that t he control of UNI expression by AF, TL, and COCH is important in the regula tion of blastozone activity and pattern formation in the compound leaf prim ordium of the pea.