Molecular characterization of NBS–LRR genes in the soybean Rsv3 locus reveals several divergent alleles that likely confer resistance to the soybean mosaic virus
Molecular characterization of NBS–LRR genes in the soybean Rsv3 locus reveals several divergent alleles that likely confer resistance to the soybean mosaic virus
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DOI：
10.1007/s00122-017-2999-9
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发表时间：
2017-10
影响因子：
5.4
通讯作者：
Fang-Fang Ma-Fang;Mian Wu;Ying-Na Liu;Xue-Ying Feng;Xun-Zong Wu;Jian-Qun Chen;Bin Wang
中科院分区：
文献类型：
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作者：
Fang-Fang Ma-Fang;Mian Wu;Ying-Na Liu;Xue-Ying Feng;Xun-Zong Wu;Jian-Qun Chen;Bin Wang
关键信息揭示了大豆Rsv 3基因座上NBS-LRR基因的分化模式，（NBS_C、NBS_D和ColumbiaNBS_E）是Rsv 3的可能功能候选基因。已被定位到一个含有5个核苷酸结合位点-富含亮氨酸重复序列（NBS-LRR）基因的区域（参考asnbs_A-E）在威廉姆斯82中。然而，在抗病品种中，NBS-LRR基因在这一区域的数量以及它们与感病等位基因的分歧仍不清楚。本研究构建并筛选了水稻抗病品种早薯18的细菌人工染色体（BAC）文库。对两个BAC阳性插入片段的测序结果表明，早薯18与威廉姆斯82具有相同的基因内容和顺序，但其中两个NBS-LRR基因NBS_D和NBS_D具有威廉姆斯82等位基因所没有的独特特征。从另外8个品种中获得的NBS_A-D基因表明，NBS_A-D基因分化为两个不同的等位基因：bs_A-D等位基因与具有RSV 3型的品种相关，而NBS_A-D等位基因与具有RSV 3型的品种相关。NBS_E基因在哥伦比亚中有一个等位基因（NBS_E），与早薯18和RSV 3型品种（nbs_E）不同。在NBS_C-E基因的等位基因上进一步检测到交换片段，表明重组是导致等位基因分化的主要力量。NBS_C-E基因的LRR结构域也显示出极强的正选择信号。总体而言，本研究阐明的Rsv 3位点的NBS-LRR基因的分化模式表明，不仅NBS_C，而且NBS_D和ColumbiaNBS_E可能是赋予SMV抗性的功能等位基因。
Key messageThe divergence patterns ofNBS–LRRgenes in soybeanRsv3locus were deciphered and several divergent alleles (NBS_C,NBS_Dand ColumbiaNBS_E) were identified as the likely functional candidates ofRsv3.AbstractThe soybeanRsv3locus, which confers resistance to the soybean mosaic virus (SMV), has been previously mapped to a region containing five nucleotide binding site–leucine-rich repeats (NBS–LRR) genes (referred to asnbs_A–E) in Williams 82. In resistant cultivars, however, the number ofNBS–LRRgenes in this region and their divergence from susceptible alleles remain unclear. In the present study, we constructed and screened a bacterial artificial chromosome (BAC) library for anRsv3-possessing cultivar, Zaoshu 18. Sequencing two positive BAC inserts on theRsv3locus revealed that Zaoshu 18 possesses the same gene content and order as Williams 82, but two of theNBS–LRRgenes,NBS_CandNBS_D, exhibit distinct features that were not observed in the Williams 82 alleles. Obtaining theseNBS-LRRgenes from eight additional cultivars demonstrated that theNBS_A–Dgenes diverged into two different alleles: thenbs_A–Dalleles were associated with thersv3-type cultivars, whereas theNBS_A–Dalleles were associated with theRsv3-possessing cultivars. For theNBS_Egene, the cultivar Columbia possesses an allele (NBS_E) that differed from that in Zaoshu 18 andrsv3-type cultivars (nbs_E). Exchanged fragments were further detected on alleles of theNBS_C–Egenes, suggesting that recombination is a major force responsible for allele divergence. Also, the LRR domains of theNBS_C–Egenes exhibited extremely strong signals of positive selection. Overall, the divergence patterns of theNBS–LRRgenes inRsv3locus elucidated by this study indicate that not onlyNBS_Cbut alsoNBS_Dand ColumbiaNBS_Eare likely functional alleles that confer resistance to SMV.