DataSheet_1_Global analysis of common bean multidrug and toxic compound extrusion transporters (PvMATEs): PvMATE8 and pinto bean seed coat darkening.zip

In common bean (Phaseolus vulgaris L.), postharvest seed coat darkening is an undesirable trait that affects crop value. The increased accumulation of proanthocyanidins (PAs) in the seed coat results in darker seeds in many market classes of colored beans after harvest. The precursors of PAs are synthesized in the cytoplasm, and subsequently get glycosylated and then transported to the vacuoles where polymerization occurs. Thus, vacuolar transporters play an important role in the accumulation of PAs. Here, we report that common bean genome contains 59 multidrug and toxic compound extrusion genes (PvMATEs). Phylogenetic analysis of putative PvMATEs with functionally characterized MATEs from other plant species categorized them into substrate-specific clades. Our data demonstrate that a vacuolar transporter PvMATE8 is expressed at a higher level in the pinto bean cultivar CDC Pintium (regular darkening) compared to 1533-15 (slow darkening). PvMATE8 localizes in the vacuolar membrane and rescues the PA deficient (tt12) mutant phenotype in Arabidopsis thaliana. Analysis of PA monomers in transgenic seeds together with wild-type and mutants suggests a possible feedback regulation of PA biosynthesis and accumulation. Identification of PvMATE8 will help better understand the mechanism of PA accumulation in common bean.

在普通菜豆（Phaseolus vulgaris L.）中，收获后种皮变暗是影响作物商品价值的不良性状。多个商品类群的有色菜豆在收获后，其种皮中原花青素（proanthocyanidins, PAs）积累增加会导致种子颜色加深。原花青素的前体在细胞质中合成，随后经历糖基化修饰，再被转运至液泡中完成聚合反应，因此液泡转运蛋白在原花青素积累过程中发挥关键作用。本研究发现，普通菜豆基因组中包含59个多药及毒性化合物外排（multidrug and toxic compound extrusion, MATE）家族基因（PvMATEs）。对推定的PvMATEs与其他植物物种中已功能验证的MATE家族基因进行系统发育分析，可将其划分为底物特异性进化分支。研究数据显示，与慢变暗品种1533-15相比，液泡转运蛋白PvMATE8在常规变暗的花豆（pinto bean）品种CDC Pintium中的表达量更高。PvMATE8定位于液泡膜，且能够互补拟南芥（Arabidopsis thaliana）中原花青素缺陷型（tt12）突变体的表型。对转基因种子、野生型种子及突变体种子中的原花青素单体进行分析，结果提示原花青素的生物合成与积累可能存在反馈调控机制。对PvMATE8的鉴定将有助于进一步阐明普通菜豆中原花青素积累的分子机制。