New components in genetic regulation of age-dependent compound leaf architecture in pea.

Pea (Pisum sativum L.) is a classic model for compound leaf development. Pea leaves typically consist of a proximal series of paired lateral leaflets substituted distally by filiform tendrils, and the number of lateral organ pairs increases with ontogeny. This gradient has been proposed as an expression of heteroblasty, but no clear links with known leaf-development pathways have been demonstrated to date. We explored potential links between lateral organ number, heteroblasty and flowering time in pea using natural and induced genetic variation, and characterize four distinct loci regulating compound leaf architecture through genetic and molecular analyses. Two previously described AEROMACULATA (AERO) loci AERO1 and AERO2 are identified as putative orthologs of Arabidopsis chromatin modifiers CURLY LEAF and PICKLE, and two novel loci EXTRA PINNA PAIRS 1 (EPP1) and EPP2 as co-orthologs of the transcriptional adaptor SEUSS. These loci interact to influence a range of pleiotropic phenotypes related to meristem function. AERO and EPP genes controlling lateral organ number in pea leaves have no clear association with leaf complexity or heteroblasty in other systems, and represent new components in regulation of legume compound leaf development.