南部根结线虫(SRKN;Meloidogyneincognita)是一种典型的寄生线虫,会影响甘薯[Ipomoeabatatas(L.)林。],导致作物产量和商业价值大幅下降。在日本,SRKN分为10个种族:SP1-SP5,SP6-1,SP6-2和SP7-SP9,主要种族根据栽培面积而有所不同。土壤杀虫剂以前曾被用来降低SRKN的土壤密度;然而,这种做法既昂贵又劳动密集型。因此,有必要开发抗SRKN的甘薯品系和品种。然而,由于多倍体遗传的复杂性和甘薯的高度异质性基因组组成,与其他主要二倍体作物物种相比,该物种的遗传信息和研究明显缺乏。在这项研究中,我们利用了最近开发的全基因组关联方法,它使用多剂量标记来评估自体多倍体物种。我们进行了关联分析,以调查对SRKN-SP2的抗性,SRKN-SP2是日本甘薯产量高的地区的主要种族。来自抗性“J-Red”和易感“Choshu”品种的F1作图群体中抗性和易感系的分离比拟合为1:3,这表明对SP2的抗性可能受两个位点的调节。通过将双消化限制性位点相关的DNA测序读段与已发布的三裂桃子参考序列进行比对,鉴定了46,982个单核苷酸多态性(SNP)(测序深度>200)。关联研究在7号染色体上产生了最高峰(Chr07),在3号染色体上产生了第二高峰(Chr03)。在两个基因座中以单剂量存在。使用在Chr03和Chr07上鉴定的SNP开发选择性DNA标记以筛选抗性植物。我们的结果表明,当结合两种选择性DNA标记时,选择具有SRKN-SP2抗性的植物的概率约为70%。这项研究作为识别控制农业性状的基因组区域和阐明其作用的模型,并有望大大推进多倍体作物物种的标记辅助育种和关联研究。
The southern root-knot
nematode (SRKN; Meloidogyne incognita) is a typical parasitic
nematode that affects sweetpotato [Ipomoea batatas (L.) Lam.], causing a significant decrease in crop yield and commercial value. In Japan, the SRKN is classified into 10 races: SP1-SP5, SP6-1, SP6-2, and SP7-SP9, with the dominant race differing according to the cultivation area. Soil insecticides have previously been used to reduce the soil density of SRKNs; however, this practice is both costly and labor intensive. Therefore, the development of SRKN-resistant sweetpotato lines and cultivars is necessary. However, due to the complexity of polyploid inheritance and the highly heterogeneous genomic composition of sweetpotato, genetic information and research for this species are significantly lacking compared to those for other major diploid crop species. In this
study, we utilized the recently developed genome-wide association approach, which uses multiple-dose markers to assess autopolyploid species. We performed an association analysis to investigate resistance toward SRKN-SP2, which is the major race in areas with high sweetpotato production in Japan. The segregation ratio of resistant and susceptible lines in the F1 mapping population derived from the resistant \"J-Red\" and susceptible \"Choshu\" cultivars was fitted to 1: 3, suggesting that resistance to SP2 may be regulated by two loci present in the simplex. By aligning the double digest restriction-site associated DNA sequencing reads to the published Ipomoea trifida reference sequence, 46,982 single nucleotide polymorphisms (SNPs) were identified (sequencing depth > 200). The association
study yielded its highest peak on chromosome 7 (Chr07) and second highest peak on chromosome 3 (Chr03), presenting as a single-dose in both loci. Selective DNA markers were developed to screen for resistant plants using the SNPs identified on Chr03 and Chr07. Our results showed that SRKN-SP2-resistant plants were selected with a probability of approximately 70% when combining the two selective DNA markers. This
study serves as a model for the identification of genomic regions that control agricultural traits and the elucidation of their effects, and is expected to greatly advance marker-assisted breeding and association studies in polyploid crop species.