| Chinese super hybrid rice Liangyoupeijiu (Oryza sativa, indica cultivar-group), its female patent Peiai 64S and male parent 9311 were used as materials. Genes differentially expressed under stress condition of photoinhibition and their genetic origins were studied by improved silver-staining mRNA differential display technique. The main results are as follows:1. Electrophoresis maps of polyacrylamide gel visualized by silver stainingThere were 24 combinations composed by 3 kinds of anchor primers and 8 kinds of random primers. RT-PCR products of every combination were separated on 6% denaturing polyacrylamide gel and stained with silver staining. We got 24 electrophoresis maps of polyacrylamide gel visualized by silver staining. But there were no differentially displayed bands amplified by the primer combination of HT11G×HAP28 in hybrid rice. 2. Differentially displayed cDNA fragments and their gene types167 differentially displayed cDNA fragments of hybrid rice under photoinhibition stress were obtained from silver-stained polyacrylamide gels, suggesting large amounts of genes in hybrid rice expressed differentially to response to photoinhibition stress. Genes expressed under photoinhibition stress could be categorised to 5 types according to the cDNA bands existed or not in the treated and control leaves on the relative positions in silver-stained polyacrylamide gels. And 54 differentially displayed cDNA fragments belonged to genes induced by photoinhibition, 41 belonged to genes sensitive to photoinhibition, 45 belonged to genes up-regulated by photoinhibition, while 27 belonged to genes down-regulated by photoinhibition. However, most amplified cDNA fragments belonged to genes stable under photoinhibition stress. 3. The genetic origins of differentially displayed cDNA fragmentsThe genetic origins of differentially displayed cDNA fragments were studied. The results suggested that most of the differentially expressed genes were inherited from both male and female parents rather than either of them. So both male and female patents of anti-photoinhibition species should be chosen to breed anti-photoinhibition hybrid rice. On the other hand, some differentially expressed cDNA fragments had no distinct genetic origins, indicating that some unclear mechanisms were involved in inheritance processes from parents to hybrid. 4. The cloning and sequencing of some differentially expressed cDNA fragments and their homology analysesSome differentially expressed cDNA fragments derived from photo- inhibition-treated hybrid rice leaves were selected to be excised from the silver-stained polyacrylamide gels and re-amplified by PCR. 11 candidate gene fragments were obtained by purification and cloning and all of them were sequenced. Their homology analyses suggested that genes of cDNA fragment HT11G×HAP25-320bp, HT11G×HAP29-280bp and HT11A×HAP31-340bp possibly encoded cytosolic monodehydroascorbate reductase (MDAR), a putative DEAH-box RNA helicase and ammonium transport protein (cysQ) in hybrid rice, respectively. And they could be involved in photo-protective processes. Genes of cDNA fragment HT11A×HAP31-380bp, HT11A×HAP31- 360bp and HT11G×HAP29-230bp possibly encoded a putative phosphatidyl- inositol 4-kinase, DNA gyrase and a putative poly(A)-binding protein, respectively. But their possible protective functions under strong light stress were still unclear. There were some highly similar sequences to cDNA fragments HT11A×HAP31-230bp and HT11A×HAP31-270bp in the NCBI database. But the genes they encoded and their protective functions under strong light stress were still unknown. In addition, cDNA fragments HT11A× HAP29-510bp, HT11C×HAP30-470bp and HT11C×HAP30-230bp had no poly(A) tails and could be non-specially amplified by random primers. And there were no distinct sequence homologies in rice GenBank.5. The pseudo-positive results of the silver-staining mRNA differential display techniqueThe silver-staining mRNA differential display technique improved by us couldn't elimina...
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