Abstract：
Sorghum anthracnose caused by the fungus Colletotrichum sublineola (Cs) is a damaging disease of the crop. Here, we describe the identification of ANTHRACNOSE RESISTANCE GENES (ARG4 and ARG5) encoding canonical nucleotide-binding leucine-rich repeat (NLR) receptors. ARG4 and ARG5 are dominant resistance genes identified in the sorghum lines SAP135 and P9830, respectively, that show broad-spectrum resistance to Cs. Independent genetic studies using populations generated by crossing SAP135 and P9830 with TAM428, fine mapping using molecular markers, comparative genomics and gene expression studies determined that ARG4 and ARG5 are resistance genes against Cs strains. Interestingly, ARG4 and ARG5 are both located within clusters of duplicate NLR genes at linked loci separated by ~1 Mb genomic region. SAP135 and P9830 each carry only one of the ARG genes while having the recessive allele at the second locus. Only two copies of the ARG5 candidate genes were present in the resistant P9830 line while five non-functional copies were identified in the susceptible line. The resistant parents and their recombinant inbred lines carrying either ARG4 or ARG5 are resistant to strains Csgl1 and Csgrg suggesting that these genes have overlapping specificities. The role of ARG4 and ARG5 in resistance was validated through sorghum lines carrying independent recessive alleles that show increased susceptibility. ARG4 and ARG5 are located within complex loci displaying interesting haplotype structures and copy number variation that may have resulted from duplication. Overall, the identification of anthracnose resistance genes with unique haplotype stucture provides a foundation for genetic studies and resistance breeding.
摘要：
由真菌Colletotrichumsublineola（Cs）引起的高粱炭疽病是作物的破坏性疾病。这里,我们描述了编码典型的核苷酸结合型富含亮氨酸重复序列(NLR)受体的Anthraconc抗性基因(ARG4和ARG5)的鉴定。ARG4和ARG5分别是在高粱系SAP135和P9830中鉴定的显性抗性基因，显示对Cs的广谱抗性。使用SAP135和P9830与TAM428杂交产生的群体进行独立遗传研究，使用分子标记进行精细定位，比较基因组学和基因表达研究确定ARG4和ARG5是针对Cs菌株的抗性基因。有趣的是,ARG4和ARG5均位于由〜1Mb基因组区隔开的连锁基因座处的重复NLR基因簇内。SAP135和P9830各自仅携带ARG基因之一,同时在第二基因座处具有隐性等位基因。在抗性P9830品系中仅存在两个拷贝的ARG5候选基因,而在易感品系中鉴定出五个非功能性拷贝。抗性亲本及其携带ARG4或ARG5的重组自交系对菌株Csgl1和Csgrg具有抗性，表明这些基因具有重叠的特异性。ARG4和ARG5在抗性中的作用通过携带显示增加的易感性的独立隐性等位基因的高粱品系得到验证。ARG4和ARG5位于复杂基因座内,显示可能由重复导致的有趣单倍型结构和拷贝数变异。总的来说,具有独特单倍型结构的抗炭疽病基因的鉴定为遗传研究和抗性育种奠定了基础。
