Huynh Bao-Lam, Ehlers Jeffrey D, Ndeve Arsenio, Wanamaker Steve, Lucas Mitchell R, Close Timothy J, Roberts Philip A
Department of Nematology, University of California, Riverside, CA 92521 USA.
Bill and Melinda Gates Foundation, Seattle, WA 98102 USA.
Mol Breed. 2015;35(1):36. doi: 10.1007/s11032-015-0254-0. Epub 2015 Jan 21.
The cowpea aphid Koch (CPA) is a destructive insect pest of cowpea, a staple legume crop in Sub-Saharan Africa and other semiarid warm tropics and subtropics. In California, CPA causes damage on all local cultivars from early vegetative to pod development growth stages. Sources of CPA resistance are available in African cowpea germplasm. However, their utilization in breeding is limited by the lack of information on inheritance, genomic location and marker linkage associations of the resistance determinants. In the research reported here, a recombinant inbred line (RIL) population derived from a cross between a susceptible California blackeye cultivar (CB27) and a resistant African breeding line (IT97K-556-6) was genotyped with 1,536 SNP markers. The RILs and parents were phenotyped for CPA resistance using field-based screenings during two main crop seasons in a 'hotspot' location for this pest within the primary growing region of the Central Valley of California. One minor and one major quantitative trait locus (QTL) were consistently mapped on linkage groups 1 and 7, respectively, both with favorable alleles contributed from IT97K-556-6. The major QTL appeared dominant based on a validation test in a related F2 population. SNP markers flanking each QTL were positioned in physical contigs carrying genes involved in plant defense based on synteny with related legumes. These markers could be used to introgress resistance alleles from IT97K-556-6 into susceptible local blackeye varieties by backcrossing.
豇豆蚜科赫氏亚种（CPA）是豇豆的一种毁灭性害虫，豇豆是撒哈拉以南非洲以及其他半干旱温暖热带和亚热带地区的主要豆类作物。在加利福尼亚州，CPA会在从营养生长早期到结荚发育生长阶段对所有当地品种造成损害。非洲豇豆种质中存在CPA抗性来源。然而，由于缺乏关于抗性决定因素的遗传、基因组定位和标记连锁关联的信息，它们在育种中的应用受到限制。在本文报道的研究中，利用1536个单核苷酸多态性（SNP）标记对由一个易感的加利福尼亚黑眼品种（CB27）和一个抗性非洲育种系（IT97K - 556 - 6）杂交产生的重组自交系（RIL）群体进行了基因分型。在加利福尼亚中央谷地主要种植区该害虫的一个“热点”位置，在两个主要作物季节期间，通过田间筛选对RIL及其亲本的CPA抗性进行了表型分析。一个微效和一个主效数量性状位点（QTL）分别始终定位在连锁群1和7上，两个位点的有利等位基因均来自IT97K - 556 - 6。基于在相关F2群体中的验证试验，主效QTL表现为显性。根据与相关豆科植物的共线性，每个QTL侧翼的SNP标记定位在携带参与植物防御基因的物理重叠群中。这些标记可用于通过回交将IT97K - 556 - 6的抗性等位基因导入易感的当地黑眼品种中。
