Liu Linya, Huang Yacheng, Huang Xiaolong, Yang Jianghua, Wu Wenqiang, Xu Yun, Cong Ziwen, Xie Jun, Xia Wei, Huang Dongyi
Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
Int J Mol Sci. 2017 Jul 20;18(7):1579. doi: 10.3390/ijms18071579.
Dioscorin is one of the major soluble proteins in yam tubers. Unlike other well-known plant storage proteins, such as patatin and sporamin, dioscorin is argued for its function as storage proteins, and the molecular mechanisms underlying its expressional complexity are little understood. In this study, we isolated five dioscorin genes from L., comprising three class A (, - and -) and two class B ( and -) isoforms. Expressions of all dioscorin genes gradually decreased in mother tubers during yam sprouting and regrowth. On the other hand, all dioscorin genes accumulated transcripts progressively with tuber development in new tubers, with being the most prominent isoform. In yam leaves, the expressions of 5 were up-regulated by the treatments of five phytohormones (gibberellic acid, salicylic acid, indole-3-acetic acid, abscisic acid, and ethylene), and three abiotic stresses (high-temperature, low-temperature and drought). To further elucidate the regulatory mechanisms of expressions, transgenic plants harboring the promoter-β-glucuronidase (GUS) fusion were generated. GUS staining showed that expressions of the promoter were detected mainly in the shoot apical meristem (SAM) and hypocotyls, and enhanced by the treatments of the five hormones, and the three abiotic stresses mentioned above. These results suggest diverse roles of in yam sprouting, regrowth, and tuberization, as well as in response to enviromental cues.
薯蓣球蛋白是山药块茎中的主要可溶性蛋白之一。与其他著名的植物贮藏蛋白，如马铃薯块茎蛋白和菠菜种子贮藏蛋白不同，薯蓣球蛋白作为贮藏蛋白的功能存在争议，其表达复杂性背后的分子机制也鲜为人知。在本研究中，我们从山药中分离出5个薯蓣球蛋白基因，包括3个A类（、和）和2个B类（和）同工型。在山药发芽和再生长过程中，母块茎中所有薯蓣球蛋白基因的表达逐渐降低。另一方面，在新块茎中，随着块茎发育，所有薯蓣球蛋白基因的转录本逐渐积累，其中是最突出的同工型。在山药叶片中，5个基因的表达受5种植物激素（赤霉素、水杨酸、吲哚-3-乙酸、脱落酸和乙烯）和3种非生物胁迫（高温、低温和干旱）处理的上调。为了进一步阐明基因表达的调控机制，构建了含有启动子-β-葡萄糖醛酸酶（GUS）融合基因的转基因山药植株。GUS染色显示，启动子的表达主要在茎尖分生组织（SAM）和下胚轴中检测到，并受上述5种激素和3种非生物胁迫处理的增强。这些结果表明，在山药发芽、再生长和块茎形成以及对环境信号的响应中具有多种作用。
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