Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, Japan.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
Plant Cell Physiol. 2018 Dec 1;59(12):2502-2511. doi: 10.1093/pcp/pcy171.
Buckwheat (Fagopyrum esculentum Moench) shows high tolerance to aluminum (Al) toxicity, but the molecular mechanisms underlying its high Al tolerance are poorly understood. Here, we functionally characterized two genes (FeSTAR1 and FeSTAR2), which encode a nucleotide-binding domain and a membrane domain, respectively, of a bacterial-type ATP-binding cassette (ABC) transporter. The expression of FeSTAR1 and FeSTAR2 was induced by Al in both roots and leaves with higher expression in the roots. Spatial and tissue-specific expression analysis showed that the Al-induced expression of these two genes was found in both the root tips and basal root regions with higher expression in the root outer cell layers. The expression was neither induced by other metals including Cd and La nor by low pH and phosphorus-deficiency. FeSTAR1 and FeSTAR2 were present in a single copy in the genome, but the Al-induced transcript copy number of FeSTAR1 and FeSTAR2 was much higher than their homologous genes in rice and Arabidopsis. FeSTAR1 and FeSTAR2 form a complex when co-expressed in onion epidermal cells. Introduction of FeSTAR1 and FeSTAR2 into Arabidopsis mutants atstar1 and als3/atstar2, respectively, rescued the sensitivity of the mutants to Al. Taken together, our results indicate that FeSTAR1 and FeSTAR2 are involved in Al tolerance and that their high expression level may contribute to high Al tolerance in buckwheat.
荞麦（Fagopyrum esculentum Moench）对铝（Al）毒性具有很高的耐受性，但对其高耐铝性的分子机制还知之甚少。在这里，我们功能表征了两个基因（FeSTAR1 和 FeSTAR2），它们分别编码细菌型 ATP 结合盒（ABC）转运蛋白的核苷酸结合域和膜域。FeSTAR1 和 FeSTAR2 的表达在根和叶中均被 Al 诱导，在根中表达更高。空间和组织特异性表达分析表明，这两个基因的 Al 诱导表达在根尖和基础根区均存在，在外根皮层中表达更高。该表达既不受其他金属（包括 Cd 和 La）的诱导，也不受低 pH 和磷缺乏的诱导。FeSTAR1 和 FeSTAR2 在基因组中各以单拷贝存在，但 FeSTAR1 和 FeSTAR2 的 Al 诱导转录物拷贝数远高于其在水稻和拟南芥中的同源基因。FeSTAR1 和 FeSTAR2 在洋葱表皮细胞中共表达时形成复合物。将 FeSTAR1 和 FeSTAR2 分别导入 Arabidopsis 突变体 atstar1 和 als3/atstar2 中，挽救了突变体对 Al 的敏感性。总之，我们的结果表明 FeSTAR1 和 FeSTAR2 参与 Al 耐受性，其高表达水平可能有助于荞麦的高耐铝性。
