Di Vittori Valerio, Bitocchi Elena, Rodriguez Monica, Alseekh Saleh, Bellucci Elisa, Nanni Laura, Gioia Tania, Marzario Stefania, Logozzo Giuseppina, Rossato Marzia, De Quattro Concetta, Murgia Maria L, Ferreira Juan José, Campa Ana, Xu Chunming, Fiorani Fabio, Sampathkumar Arun, Fröhlich Anja, Attene Giovanna, Delledonne Massimo, Usadel Björn, Fernie Alisdair R, Rau Domenico, Papa Roberto
Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università Politecnica delle Marche, via Brecce Bianche, Ancona, Italy.
Max Planck Institute of Molecular Plant Physiology, Am Müehlenberg, Potsdam-Golm, Germany.
J Exp Bot. 2021 Feb 27;72(5):1617-1633. doi: 10.1093/jxb/eraa553.
In legumes, pod shattering occurs when mature pods dehisce along the sutures, and detachment of the valves promotes seed dispersal. In Phaseolus vulgaris (L)., the major locus qPD5.1-Pv 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 AtMYB26 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 PvMYB26 in dehiscent pods. Detailed histological analysis establishes that pod indehiscence is associated with 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 it is the result of selection at orthologous loci.
在豆科植物中，当成熟豆荚沿着缝线开裂时就会发生荚果炸裂，瓣膜分离促进种子传播。在菜豆（Phaseolus vulgaris (L).）中，最近鉴定出了控制豆荚不裂的主要基因座qPD5.1-Pv。我们构建了一个BC4/F4导入系群体，并将主要基因座缩小到一个22.5 kb的区域。在此，通过对开裂和不开裂豆荚进行基因表达及平行组织学分析，在最高关联峰下游约11 kb的基因组区域鉴定出一个AtMYB26直系同源基因作为豆荚炸裂丧失的最佳候选基因。基于定位和表达数据，我们推测在开裂豆荚中PvMYB26存在早期且精细的上调。详细的组织学分析表明，豆荚不裂与腹侧鞘中缺乏功能性离层有关，并且菜豆中与荚果炸裂相关的关键解剖学变化发生在豆荚发育的早期。我们最终提出，豆科植物中荚果炸裂丧失是组织学趋同进化的结果，并且是直系同源基因座选择的结果。
