【作者】 俞志明；

【导师】 吴平；

【作者基本信息】 浙江大学 ， 植物学， 2010， 博士

【摘要】 根毛是植物从土壤中吸收养分及水分的重要器官,并提供一个根系与微生物互作的环境。根毛发育可分为三个阶段：细胞命运决定,根毛起始,及根毛伸长。植物根毛的机制研究目前主要集中在拟南芥中,水稻中报道较少。在拟南芥的报道中发现AtEXPA7与AtEXPA18与根毛的发育有关,但是AtEXPA7的T-DNA插入纯合突变体没有发现任何根毛突变表型。推测可能是同源基因AtEXPA18的功能互补,也可能由于EXPANSIN家族其他功能冗余的基因。在水稻中,OsEXPA17基因发生点突变后,出现了短根毛表型。采用RNAi技术,抑制该基因表达也出现了短根毛表型。由此证实,点突变导致了OsEXPA17蛋白质失去了功能。点突变使第104位的氨基酸序列发生改变,由Gly变成了Arg。根据已报道的ZmEXPB1晶体结构分析推知,OsEXPA17第103位及第106位处的两个半胱氨酸,它们分别与第74位及第180位半胱氨酸形成二硫键。因此推测可能由于G104R的改变而使这两个二硫键形成受到了影响,而导致OsEXPA17蛋白功能丧失。同源基因OsEXPA30, AtEXPA7互补实验发现,OsEXPA30能够部分回复OsexpA17短根毛表型,AtEXPA7也同样能够部分回复OsexpA17短根毛表型。说明EXPA7亚家族对根毛伸长功能是保守的。通过质壁分离发现,OsEXPA17、OsEXPA30及OsexpA17是个一个膜蛋白。更多还原

【Abstract】 Root hair is an important organ for plants to uptake nutrients and water from the rhizosphere and serves as a site of interaction with soil microorganisms. Root hair development can be divided into three stages:cell specification, initiation, and elongation. Extensive studies have been reported on root hair development in Arabidopsis (the dicot model plant). In rice (the monocot model plant) the knowledge on root hair development is still limited.It has been reported in Arabidopsis that AtEXPA7 and AtEXPA18 are tightly linked to root hair initiation and development. But the homozygous T-DNA insert mutant of AtEXPA7 has no obvious compaired phenotype with the wild type in root hair, for which the functional redundancy by AtEXPA18 and perhaps other expansin genes.A short root hair mutant caused by mutation of OsEXPA17, is a orthology gene of AtEXPA7, has been founded. RNA interference of OsEXPA17 gene also results in short root hair phenotype, which conforms that the point mutant of OsEXPA17 makes the gene function lost. The point mutation results in a change of 104th site amino acid Gly to Arg. There are two cysteines in 103th site and 106th site near 104th site which can form two disulfide linkage with 74th site and 180th site cysteines alternatively. So we presume the amino acid change in 104th site may influence the disulfide linkage structure.Overexpressing OsEXPA30 and AtEXPA7 can partially restore OsexpA17 short root hair mutant.Through transient expression of OsEXPA17, OsEXPA30 and OsexpA17, we discover that they are plasma membrane proteins through plasmolysis.更多还原