大花蕙兰授粉后子房cDNA差异表达片段序列分析

 应用mRNA差异显示(DDRT-PCR) 方法比较分析了大花蕙兰(Cymbidium hybridium ) 授粉后2 d与未授粉子房的基因表达差异。结果分离到了7个在授粉后子房中特异表达的cDNA片段, 分别命名为CDD-313, CDD-272, CDD-265, CDD-243, CDD-193, CDD-218,CDD-470。在GenBank中进行同源性比较发现前4个没有同源序列与之匹配; 后3个片段推导的氨基酸序列分别与ABC型transporter, GTPase和40S核糖体蛋白质S3 (RPS3) 有高度同源性。反向Northern杂交进一步证实它们存在, 并在授粉子房中高度表达。其中, 最为有意义的是CDD-470, 其推定的氨基酸与参与细胞生长分化的植物源多功能蛋白RPS3高度同源性, 进而推测其与RPS3有相似的功能, 可能与兰花子房发育有关, 这为解释花发育分子机制提供了新资料。

Sequence Analysis of the cDNA Fragments Differentially Expressed in the Ovaries of Cymbidium hybridium after Pollination

In this study, we identified and characterized seven cDNA fragments differentially expressed in the pollinated and non-pollinated ovaries of Cymbidium hybridium using mRNA differential display RT-PCR (DDRT-PCR). Deduced amino-acid sequences of four of the seven cDNA fragments (CDD-313, CDD-272, CDD-265, CDD-243) showed no significant homology with ESTs and genes in the Genbank databases. However, the remaining three (CDD-193, CDD-218, CDD-470) showed significant homologies with sequences encoding components of an ABC-type transporter, GTPase and 40S ribosomal S3 proteins (RPS3), respectively. Their differential expression patterns were confirmed by reverse Northern blot analysis. CDD-470, which encoded a new factor of RPS3 participating in cell growth and proliferation, appeared to be present and highly expressed in the pollinated ovaries. Based on these results, we deduced that this 40S ribosomal S3 like protein was most likely involved in the ovary development of orchids, and the study gave us novel insights into the molecular mechanism of the ovary and floral development of orchids.