不结球白菜抗病基因同源序列的克隆及分析

【目的】利用同源序列法分离不结球白菜抗病基因同源序列。【方法】根据植物抗病基因TIR-NBS-LRR保守区设计简并引物，对不结球白菜基因组DNA及cDNA进行PCR扩增。【结果】获得了10个具有通读氨基酸序列的片段。同源性比较发现，该10个片段均属于TIR-NBS-LRR类抗病基因同源序列（RGA），与已知R基因相应区段的氨基酸序列一致性为50%～66%。与已知抗病基因聚类分析结果显示，该10个RGA序列可以分为5大类。利用RGA950作为探针进行Southern杂交，结果表明，其在基因组中存在多拷贝。【结论】本研究成功获得了不结球白菜RGA序列，为进一步克隆不结球白菜的R基因奠定了基础。

Isolation and Characterization of Resistant Gene Analogs from Brassica campestris ssp.chinensis

Objective ] Resistance gene analogs from Brassica campestris ssp.chinensis were isolated using homology-based method. Method] The degenerated primers were designed according to the conservative domain TIR-NBS-LRR of most disease resistant genes in plants,and the genomic DNA and cDNA of B. campestris ssp.chinensis were amplified. Result ] Ten resistant gene analogs were obtained which contain the TIR-NBS-LRR domain. The deduced amino acid sequences have different homology scores compared with those of resistance genes or resistance gene analogs from other plants in GeneBank. A cluster analysis was performed based on the deduced amino acid sequences with several resistance genes from other plants, these RGAs can be classified into five major groups. Using RGA950 as probe, Southern bloting analysis showed there existed multi-copies in genomic DNA of Xuekeqing. Conclusion] These RGAs can further be used as probes for cloning of resistance gene in B. campestris ssp.chinensis.