Abstract:

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 aminoacid 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.

Key words: Cymbidium hybridium, Differential display RT-PCR (DDRT-PCR), Floral development, 40S ribosomal S3 protein (RPS3)