从棉花cDNA文库中分离了3个编码富含甘氨酸蛋白(glycine-rich proteins,GRPs)的基因,分别命名为GhGRP1、GhGRP2、GhGRP3.推断的编码蛋白质的氨基酸序列都富含甘氨酸,甘氨酸含量超过40%.而且GhGRP1和GhGRP2蛋白质序列同源性高达99%,仅在C末端有1个氨基酸残基(Arg/Pro)的差别.这3个蛋白在富含甘氨酸区相互显示较高的同源性,GhGRP1与GhGRP2达到100%,而GhGRP2与GhGRP3达到45·1%,但它们与基因数据库中其它蛋白质的同源性很低.根据结构域的组织特点,将GhGRP1和GhGRP2归为C端富含半胱氨酸结构域(C-cysteine-rich)类GRP,将GhGRP3归为N端有信号肽的GRP.GhGRP1和GhGRP2都含有12个GGX(此处X代表P/W/F)重复,GhGRP3含有22个GGX(此处X代表A/F/V/L/T/P)重复.此外,它们还含有不同数量GX,GGGX等的重复.实时RT-PCR分析表明,GhGRP1在花药中优势表达.GhGRP2在10dpa(day post anthesis)胚珠中表达最强,10dpa纤维和下胚轴次之,而在花药、根和花瓣中表达量相对较低.GhGRP3在花药,根和下胚轴中表达量较高,而在子叶,花瓣、纤维和胚珠中表达较低.上述结果表明,GhPRP基因家族的不同成员可能分别在棉花不同组织细胞的发育过程中发挥作用.
To investigate the expression pattern of GhSCFP which was isolated from cotton fiber cDNA library, a 1006 bp upstream fragment of the gene was cloned by chromosome walking and fused to GUS and GFP respectively. Histochemical GUS and GFP fluorescence analysis revealed that the expression of the report genes driven by the promoter sequence was detectable only in outer layer cells during the seed development in the transgentic tobaccos. In transgenic cotton, strong GUS activity was observed in spherical protrusions on 0 dpa (days post anthesis) ovule surface, and in the 2―36 dpa fiber cells, while no GUS signals were detected in the root, leaves, stem, corolla, anther and stigma. Our data demonstrated that GhSCFP upstream sequence is a cotton fiber-specific promoter and this promoter will be useful in the molecular research on fiber cell development and in cotton fiber improvements by genetic modification.
HOU Lei LIU Hao LI JiaBao YANG Xia XIAO YueHua LUO Ming SONG ShuiQing YANG GuangWei PEI Yan
