黄瓜果瘤性状的遗传调控机制

Cucumber is one of important vegetable crops whose fruit is the most important economic character. Tuberculate fruit (Tu) is a peculiar and important sensory quality trait. The morphogenesis of tuberculate fruit could result from the increased numbers of cells according to the morphology and histocytology research. There are spines on warty fruit, which belong to fruit trichome, and the two kind of molecular mechanisms are unknown. There are no warts and spines on the fruit surface of gl (glabrous), the gl gene of which had a recessive epistasis effect on Tu. The Tu and gl would be isolated from cucumber by map-based cloning, while performing RNA in situ hybridization, fluorescence Q-PCR analysis, genetic transformation and transcriptome analysis of transgenic plants which combining with the fluorescent protein to screen the related genes. Based on those researches, discuss the mechanism and morphogenesis of wart and spine to clarify epigenetic regulation of the Tu and gl gene in cucumber.

黄瓜是重要的蔬菜作物之一，果实是黄瓜经济性状最重要的部分。果瘤（Tu, Tuberculate fruit）性状是黄瓜所特有的，而且是黄瓜重要的感官品质性状之一。形态和组织细胞学研究表明，黄瓜果瘤形态建成的原因很可能是由于细胞数目增多造成。黄瓜果瘤之上长着果刺，后者属于表皮毛，这两个性状的分子机制尚未知。黄瓜无毛突变体gl（glabrous）的果实表面没有果刺和果瘤，无毛基因gl对果瘤基因Tu存在隐性上位作用。利用黄瓜Tu/tu材料和无毛突变体gl，通过图位克隆分离Tu和gl基因，进行RNA原位杂交、荧光定量PCR分析和遗传转化，以及利用与荧光蛋白融合表达的转化植株的转录组分析，筛选出相关联的基因，探讨黄瓜刺和瘤的形态建成机理，为进一步阐明其中的遗传调控网络打下基础。

黄瓜是重要的蔬菜作物之一，果实是黄瓜经济性状最重要的部分。果瘤（Tu, Tuberculate fruit）性状是黄瓜所特有的，而且是黄瓜重要的感官品质性状之一，果瘤之上长着果刺，后者属于表皮毛。黄瓜微毛突变体micro-trichome (mict)的果实表面没有果瘤，无刺（微毛），mict对Tu存在隐性上位作用。我们通过图位克隆分离获得Tu和mict基因。前者编码一种C2H2型锌指蛋白，属于转录因子，在果瘤之上的刺部位特异表达，无果瘤品种中该基因完全缺失。Mict基因编码Ⅰ型同源异型域－亮氨酸拉链转录因子，该基因特异表达于表皮毛的顶细胞，控制多细胞表皮毛的正常发育。Mict基因可能调控Tu基因的表达， Tu基因很可能通过调控细胞分裂素（CTK）通路上的CTK-羟化酶基因Csa5M644580和Csa5M224130，参与CTK的合成调节，最终导致果瘤形成。本项目研究为进一步阐明黄瓜刺和瘤的形态建成机理打下基础。