Table_3_Marker-assisted introgression of wild chromosome segments conferring resistance to fungal foliar diseases into peanut (Arachis hypogaea L.).xlsx

IntroductionFungal foliar diseases can severely affect the productivity of the peanut crop worldwide. Late leaf spot is the most frequent disease and a major problem of the crop in Brazil and many other tropical countries. Only partial resistance to fungal diseases has been found in cultivated peanut, but high resistances have been described on the secondary gene pool.MethodsTo overcome the known compatibility barriers for the use of wild species in peanut breeding programs, we used an induced allotetraploid (Arachis stenosperma × A. magna)4x, as a donor parent, in a successive backcrossing scheme with the high-yielding Brazilian cultivar IAC OL 4. We used microsatellite markers associated with late leaf spot and rust resistance for foreground selection and high-throughput SNP genotyping for background selection.ResultsWith these tools, we developed agronomically adapted lines with high cultivated genome recovery, high-yield potential, and wild chromosome segments from both A. stenosperma and A. magna conferring high resistance to late leaf spot and rust. These segments include the four previously identified as having QTLs (quantitative trait loci) for resistance to both diseases, which could be confirmed here, and at least four additional QTLs identified by using mapping populations on four generations.DiscussionThe introgression germplasm developed here will extend the useful genetic diversity of the primary gene pool by providing novel wild resistance genes against these two destructive peanut diseases.

引言：真菌性叶片病害对全球花生作物产量影响极大。晚疫病是该作物在巴西及众多热带国家最为常见的病害，亦构成其主要问题。在栽培花生中，仅发现对真菌病害的部分抗性，但已在次级基因库中描述了高度抗性。方法：为克服野生种在花生育种计划中使用的已知兼容性障碍，本研究以诱导的四倍体杂种（Arachis stenosperma × A. magna）4x作为供体亲本，采用连续回交方案与高产巴西品种IAC OL 4进行杂交。本研究利用与晚疫病和锈病抗性相关的微卫星标记进行前景选择，并使用高通量SNP基因分型进行背景选择。结果：借助这些工具，我们培育出具有高栽培基因组恢复率、高产潜力和来自A. stenosperma和A. magna的野生染色体片段的农艺适应型系，这些片段包括之前已确定的四个具有对两种疾病抗性QTL（数量性状位点）的片段，这些片段在此得到了证实，并且通过在四代遗传群体中应用映射，至少还确定了四个额外的QTL。讨论：本研究开发的导入种质将通过对这两种破坏性花生病害提供新的野生抗性基因，从而扩展初级基因库的有用遗传多样性。