| Soybean plant is an important economic crop. Soybean frogeye leaf spot is one of serious disease during soybean growing stage. The pathogen of this disease is Cercospora sojina. Cloning of soybean resistance C.sojina relevant genes should provided materials for gene engineering of soybean resistance disease and helped us to understand the molecular mechanism of soybean resistance against C.sojina. Soybean transgened with hrfl gene, which has functions of inducing resistance to pathogen and insects, enhance plant growth, should offered high resistance levels soybean varieties.Cloning of soybean relevant genes to resistance against C.sojina 1. Cloning and sequence analysis of soybean cDNA relevant to resistance against C.sojina and specific induced by the pathogenBy an mRNA differential display protocol, 74 cDNA fragments were obtained from soybean plants inoculated with two different races of C.sojina. Thirty-three fragments were subsequently determined to be associated with resistance to the pathogen in the plant, based on Southern, reverse northern, and northern blot hybridization. Advanced analyses of these cDNAs revealed several ones that are implicated in resistance. The cDNA DN23M shows partial homology with the 3'-terminus of Glycine max major latex protein homologue (msg), which appears to be a pathogenesis related or resistance-related protein and belongs to the PRIO/Bet v 1/MLP protein family. Secondly, cDNA DN32M has a high homologue with G.max glycine-rich RNA-binding protein (GRP), which was considered involved in a resistance mechanism based on mRNA splicing.Moreover, cDNAs DN32M, DN40M and DN43M contain a region highly homologous with lectins. Deduced partial proteins possess a conserved domain of the Legume lectin, LegA, but are distinct from known soybean lectins. Therefore, we propose that these might be an undiscovered type of lectins in soybean, which involved in the mechanism of soybean resistance C.sojina.2.Reverse PCR analysis of soybean cDNA relevant to resistance against C.sojina and specific induced by the pathogenReverse PCR programs were conducted to amplify 5' and 3'-terminal sequences of the partial cDNA sequence of soybean cDNAs relevant to the resistance against C.sojina and specific induced by the pathogen, as described in the last chapter of this thesis. Primers used were synthesized based on sequences of cDNA clones we got and allowed for amplification of sequences flanking sufficient length of the cloned cDNAs and anticipated termini. By the protocols, two terminal parts of the DN45M clone were obtained. Complete sequence of the positive clone IPPDN45M has been obtained, as revealed by assembling these mutual flanked sequences and analyses of IPPDN45M-SacI fragments. Bioinformatical analyses suggest that IPPDN45M contain a complete gene that encodes a lectin or a lectin-like protein named IPPDN45M-P. Amino acid components and orders in the putative IPPDN45M-P indicate that the protein contains a functional domain GAL-Lectin found in other lectins.Transgenic expression of the hrfl gene in soybean confers pathogen defense.Some hrp genes in the hrp gene cluster in plant pathogenic bacteria encode nonspecific elicitors named harpins. Harpins elicit hypersensitive cell death (HCD) in nonhost plants of bacteria and induce resistance to pathogens and insects in many plants. In this study, hrfl gene, which encodes harpinXoo of Xanthomonas oryzae pv. oryzae, was transferred into soybean by pollen tube pathway. Transgenic expressing of the hrfl gene in soybean confers resistance to C. sojina. Genes LOX2, PAL1, CHS8, which are involved in pathogen defense, were expressed to various levels inhrf1-expressing transgenic soybean lines.
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