Análisis funcional de genes reguladores del desarrollo floral de guisantes (Pisun sativum L.).

Abstract

In an attempt to understand the molecular mechanisms that control the initiation and flower development processes in pea floral we aimed to achieve the following objectives: FIRST:-Functional analysis of the pea MADS genes PEAM1, PEAM4 y PEAM6 by two types of approaches, alternative to the pea transformation: (i) analyzing the resulting phenotype of the constitutive expression in wild type plants of heterologous systems Arabidopsis thaliana and Nicotiana tabacum and (ii) testing the ability of the PEAM1 and PEAM4 genes to rescue the defects of Arabidopsis mutants. SECOND.- The use the two hybrid system in yeast in order to: (i) identify proteins that interact with products of the pea MADS genes PEAM4 y PEAM6 and (ii) assay the interaction between PEAM4 and PEAM6 proteins. The results of constitutive expression of PEAM1 in wild-type plants of Arabidopsis and tobacco, and the specific rescue of pi-1 mutation confirm that PEAM1 is the pea PI function homologue. Our results indicate that PEAM4 is the functional homologue to AP1 and SQUA that PEAM4, despite lacking a canonical CaaX-box, functions as a floral meristem identity gene in heterologous systems Arabidopsis and tobacco since accelerates flowering and besides induces inflorescence to flower conversion in Arabidopsis. Moreover, PEAM4 was able to restore perianth organ identity in the strong mutant ap1-1 of Arabidopsis suggesting that it could function as an A-class gene in pea. The constitutive expression of PEAM6 accelerates flowering in tabacco and Arabidopsis, and besides induces inflorescence to flower conversion in Arabidopsis. This agrees with the hypothesis that PEAM6 could be involved in floral initiation in pea previously suggested by genetic evidences that correlates this gene with pea veg1 mutation and by its early expression in floral meristems. But, the resulting phenotype of the constitutive expression also compatible with a role as SEP gene which share sequence homology; the data suggest that PEAM6 could carried out a double role in pea as a floral initiation and also organ identity gene. Finally, PEAM4 and PEAM6 interact in planta during floral initiation and their proteins interact in yeast in a two-hybrid assay.