National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
College of Biological and Food Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China.
Plant Physiol. 2022 Jun 27;189(3):1466-1481. doi: 10.1093/plphys/kiac118.
Red foliated cotton is a typical dominant mutation trait in upland cotton (Gossypium hirsutum). Although mutants have been described, few responsible genes have been identified and characterized. In this study, we performed map-based cloning of the red foliated mutant gene (Re) derived from the cross between G. hirsutum cv. Emian22 and G. barbadense acc. 3-79. Through expression profiling, metabolic pathway analysis, and sequencing of candidate genes, Re was identified as an MYB113 transcription factor. A repeat sequence variation in the promoter region increased the activity of the promoter, which enhanced the expression of Re. Re expression driven by the 35S promoter produced a red foliated phenotype, as expected. When the gene was driven by a fiber elongation-specific promoter, promoter of α-expansin 2 (PGbEXPA2), Re was specifically expressed in 5- to 10-day post-anthesis fibers rather than in other tissues, resulting in brown mature fibers. Re responded to light through phytochrome-interacting factor 4 and formed a dimer with transparent testa 8, which increased its expression as well as that of anthocyanin synthase and UDP-glucose:flavonoid 3-o-glucosyl transferase, and thus activated the entire anthocyanin metabolism pathway. Our research has identified the red foliated mutant gene in cotton, which paves the way for detailed studies of anthocyanin and proanthocyanidin metabolism and pigment accumulation in cotton and provides an alternative strategy for producing brown fiber.
红叶突变体是陆地棉（Gossypium hirsutum）的一种典型显性突变性状。尽管已经描述了突变体，但很少有负责的基因被鉴定和表征。在这项研究中，我们通过对陆地棉品种 EMian22 和 G. barbadense acc. 3-79 杂交产生的红叶突变体基因 Re 进行图位克隆。通过表达谱分析、代谢途径分析和候选基因测序，鉴定 Re 为 MYB113 转录因子。启动子区域的重复序列变异增加了启动子的活性，从而增强了 Re 的表达。35S 启动子驱动的 Re 表达产生了红叶表型，这与预期一致。当基因由纤维伸长特异性启动子驱动时，即 PGbEXPA2 的启动子，Re 特异性地在 5-10 天的开花后纤维中表达，而不是在其他组织中表达，导致棕色成熟纤维。Re 通过光受体相互作用因子 4 做出响应，并与透明种皮 8 形成二聚体，这增加了它的表达以及类黄酮合酶和 UDP-葡萄糖：类黄酮 3-O-葡萄糖基转移酶的表达，从而激活了整个类黄酮代谢途径。我们的研究鉴定了棉花中的红叶突变基因，为详细研究棉花中的类黄酮和原花青素代谢以及色素积累铺平了道路，并为生产棕色纤维提供了一种替代策略。
