Degenerated PCR using primers targeted to NBS conserved motifs is a rapid and facile strategy for isolation of NBS sequences linked to disease resistance genes. This PCR-based approach was used isolate and characterize a NBS-LRR like resistance gene analog (GenBank Accession No. AY739270) from banana, which was named B-NBS.After the multialignment with NBS domains of other six known plant R proteins, four NBS conserved domains were genetic distance of B-NBS with NBS domains of other six known plant R proteins was found smaller than 21.7. This showed that B-NBS was an NBS-LRR like resistance gene analog (RGA). This will lay a RGAs resources foundation for cloning banana R-gene and studying its disease resistance mechanism.%根据大多数抗病基因的核苷酸结合区(NBS)和富含亮氨酸重复序列(LRR)保守区的氨基酸序列设计PCR简并引物,利用快速而又可行的简并PCR技术获得NBS-LRR类抗病基因类似序列.笔者利用该技术从香蕉cDNA中获得了一个NBS-LRR类抗病基因类似序列,命名为B-NBS(AY739270).结构域分析发现,B-NBS含有NBS蛋白所具有的P-Loop、Kinase-2、Kinase-3a和下游疏水GLPLAL结构域(HD,GLPLAL)4个保守基序.聚类分析发现,B-NBS与已报道的6个植物抗病基因的NBS基序的遗传距离在21.7之内.因此,B-NBS是一个香蕉NBS-LRR类抗病基因类似序列.本研究将为香蕉抗病基因克隆和抗病机理研究提供新的抗病候选基因资源.
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