Pod indehiscence in common bean is associated to the fine regulation of<i>PvMYB26</i>and a non-functional abscission layer

<jats:title>ABSTRACT</jats:title><jats:p>In legumes, pod shattering occurs when mature pods dehisce along the sutures, and detachment of the valves promotes seed dispersal. In<jats:italic>Phaseolus vulgaris</jats:italic>, the major locus<jats:italic>qPD5.1-Pv</jats:italic>for pod indehiscence was identified recently. We developed a BC4/F4 introgression line population and narrowed the major locus down to a 22.5-kb region. Here, gene expression and a parallel histological analysis of dehiscent and indehiscent pods identified an<jats:italic>AtMYB26</jats:italic>orthologue as the best candidate for loss of pod shattering, on a genomic region ~11 kb downstream of the highest associated peak. Based on mapping and expression data, we propose early and fine up-regulation of<jats:italic>PvMYB26</jats:italic>in dehiscent pods. Detailed histological analysis establishes that pod indehiscence is associated to the lack of a functional abscission layer in the ventral sheath, and that the key anatomical modifications associated with pod shattering in common bean occur early during pod development. We finally propose that loss of pod shattering in legumes resulted from histological convergent evolution and that this is the result of selection at orthologous loci.</jats:p><jats:sec><jats:title>One-sentence summary</jats:title><jats:p>A non-functional abscission layer determines the loss of pod shattering; mapping data, and parallel gene expression and histological analysis support<jats:italic>PvMYB26</jats:italic>as the candidate gene for pod indehiscence.</jats:p></jats:sec>