分子伴侣AKR2A调控棉籽油合成和棉纤维发育的分子机制

The Arabidopsis ankyrin-repeat containing protein 2A (AKR2A) is a newly discovered regulatory protein that functions as a highly efficient molecular chaperone. Our preliminary data indicate that AKR2A interacts with a group of membrane proteins (enzymes) in VLCFA (very-long-chain fatty acid) synthesitic metabolism pathway in Arabidopsis.AKR2A is found to be highly expressed in reproductive organs such as immuture seeds. the density and length of leaf trichomes and content of VLCFAs in seeds are increased significantly in the AKR2A-overexpressing plants.However,they were found to be decreased in the akr2a mutant plants when compared the wild-type plants. VLCFA was proved to promote Arabidopsis and cotton fiber cell elongation. The oil content was increased in the AKR2A-overexpressing transgenic cotton seeds,and then did affect substantially on the fiber yield with an increased in 8.6%.Therefore, AKR2A should play important roles in VLCFA metabolism and the subsequent cotton fiber development at the upstream regulatory networks in cotton. .The objectives of our research project are ①.identification of AKR2A’s interacting proteins involved VLCFA metabolism by using a large scale yeast two-hybrid screens，study of the interacting mechanism between AKR2A and its interacting proteins. ②.Study the cotton fiber development and growth, and the regulatory mechanism mediated by VLCFA biosynthetic pathway, Cloning and identifying new functional genes during early cotton fiber development.③Making a technical assessment of the transgenic cotton varity （strain） as a dual-purpose of oil and fiber. This study is expected to reveal molecular chaperone-mediated upstream regulatory networks of VLCFA metabolism, and enrich the achievement of molecular chaperones as regulatory elements of the biogenesis of membrane-binding proteins. It could also be further clarified the VLCFA-mediated molecular mechanism of cotton fiber development. Furthermore, the results may construct a genetic engineering system to create a dual-purpose new cotton variety of oil and fiber intentionally.

AKR2A是拟南芥中最新发现的高效分子伴侣。进一步研究发现AKR2A与一组超长脂肪酸（VLCFA）合成关键膜蛋白酶有相互作用。AKR2A在未成熟种子高表达。过量表达AKR2A，叶表皮毛密度和长度增加、种子VLCFAs含量提高，而AKR2A突变体正好相反。VLCFA被证明能促进拟南芥和棉纤维细胞伸长。AKR2A过量表达植株中棉籽油含量提高,继而棉纤维产量也增加了8.6%。我们推断，AKR2A处在VLCFA途径的上游调控棉籽油和棉纤维发育。项目以拟南芥和棉花为对象：①通量筛选AKR2A调控的VLCFA合成酶,明确之间的互作方式。②探明AKR2A介导VLCFA的棉籽油和棉纤维发育机制，鉴定新的基因。③AKR2A转基因棉花作为油脂兼用品种的技术评估。本研究学术上可丰富伴侣蛋白在膜蛋白生物生成中的学术成果，从基因上游阐明VLCFA介导的棉纤维发育机制；技术上有望创建油和纤维兼用品种。

分子伴侣在植物细胞新生肽链的正确运转和定位中起重要作用。AKR2A (Ankyrin-Repeat containing protein 2A)是近来被鉴定并证明的少数高效分子伴侣。本项目通过①通量筛选AKR2A调控的超长链脂肪酸（VLCFA）合成酶,研究他们之间的互作方式。②研究AKR2A介导VLCFA合成的棉籽油和棉纤维发育的分子机制，鉴定与AKR2A互作的新的基因。③创制AKR2A棉花转基因植株，作为油脂和纤维兼用品种，进行应用价值技术评估。主要结果有①提出了与AKR2A相互作用、参与VLCFA合成调控的蛋白名录,筛选到26个基因，包括KCS家族酶、细胞色素类酶、ACYL-COA BINDING PROTEIN 家族酶、角鲨烯合成酶等,明确了AKR2A与主要互作基因之间的互作方式。②探明了AKR2A介导VLCFA合成的棉籽油和棉纤维发育的分子机制，鉴定了多个与AKR2A互作的新的基因。AKR2A、KCS1双基因过量表达种子含油量高于单基因过表达种子，而这3种转基因种子含油量均高于野生型，VLCFA的绝对含量比野生型高9.4-30.8%，VLCFA占总脂肪酸的百分比高5.5个百分点。证明AKR2A处在VLCFA途径的上游参与调控棉纤维发育过程，这个过程同样影响了棉纤维合成相关激素的合成和钙离子信号途径的变化和协同。③创制了AKR2A过量表达棉花转基因植株，棉籽油的组分和含量得到了提高，继而棉纤维产量增加了8.6%。进行了转基因棉花品系的应用价值技术评估。. 通过AKR2A及其底物功能的研究，我们发现AKR2A处在VLCFA途径的上游调控棉纤维发育，同时影响棉籽油的组分和含量。本研究从基因上游阐明了AKR2A介导VLCFA调控棉纤维发育机制，进一步深入了解棉纤维伸长的分子机制，技术上创制的棉花转基因植株有望成为棉籽油和棉纤维兼用棉花新品种在育种中应用。. 项目发表论文7篇，其中SCI 7篇，发表在Plant Biotechnology Journal 、Plant Cell and Environment, Plant Science等杂志上。授权发明专利2项。培养博士后2名，研究生4名。