Identification of an ERECTA gene and its drought adaptation associations with wild and cultivated common bean.

In this research, we cloned and accessed nucleotide diversity in the common bean ERECTA gene which has been implicated in drought tolerance and stomatal patterning. The homologous gene segment was isolated with degenerate primer and was found to be located on Chromosome 1. The gene had at least one paralog on Chromosome 9 and duplicate copies in soybean for each homolog. ERECTA-like genes were also discovered but the function of these was of less interest due to low similarity with the ERECTA gene from Arabidopsis. The diversity of the 5' end of the large Chr. 1 PvERECTA gene was evaluated in a collection of 145 wild and cultivated common beans that were also characterized by geographic source and drought tolerance, respectively. Our wild population sampled a range of wet to dry habitats, while our cultivated samples were representative of landrace diversity and the patterns of nucleotide variation differed between groups. The 5' region exhibited lower levels of diversity in the cultivated collection, which was indicative of population bottlenecks associated with the domestication process, compared to the wild collection where diversity was associated with ecological differences. We discuss associations of nucleotide diversity at PvERECTA with drought tolerance prediction for the genotypes.