Department of Nematology, University of California Riverside, Riverside, California, USA.
PLoS One. 2013 Jul 30;8(7):e70041. doi: 10.1371/journal.pone.0070041. Print 2013.
The stay-green phenomenon is a key plant trait with wide usage in managing crop production under limited water conditions. This trait enhances delayed senescence, biomass, and grain yield under drought stress. In this study we sought to identify QTLs in cowpea (Vigna unguiculata) consistent across experiments conducted in Burkina Faso, Nigeria, Senegal, and the United States of America under limited water conditions. A panel of 383 diverse cowpea accessions and a recombinant inbred line population (RIL) were SNP genotyped using an Illumina 1536 GoldenGate assay. Phenotypic data from thirteen experiments conducted across the four countries were used to identify SNP-trait associations based on linkage disequilibrium association mapping, with bi-parental QTL mapping as a complementary strategy. We identified seven loci, five of which exhibited evidence suggesting pleiotropic effects (stay-green) between delayed senescence, biomass, and grain yield. Further, we provide evidence suggesting the existence of positive pleiotropy in cowpea based on positively correlated mean phenotypic values (0.34< r <0.87) and allele effects (0.07< r <0.86) for delayed senescence and grain yield across three African environments. Three of the five putative stay-green QTLs, Dro-1, 3, and 7 were identified in both RILs and diverse germplasm with resolutions of 3.2 cM or less for each of the three loci, suggesting that these may be valuable targets for marker-assisted breeding in cowpea. Also, the co-location of early vegetative delayed senescence with biomass and grain yield QTLs suggests the possibility of using delayed senescence at the seedling stage as a rapid screening tool for post-flowering drought tolerance in cowpea breeding. BLAST analysis using EST sequences harboring SNPs with the highest associations provided a genomic context for loci identified in this study in closely related common bean (Phaseolus vulgaris) and soybean (Glycine max) reference genomes.
持绿现象是一种关键的植物特性，在有限水资源条件下管理作物生产中具有广泛的用途。该特性增强了干旱胁迫下的延迟衰老、生物量和籽粒产量。在本研究中，我们试图鉴定在布基纳法索、尼日利亚、塞内加尔和美国进行的有限水资源条件下的 13 项实验中一致的豇豆（Vigna unguiculata）数量性状位点（QTL）。使用 Illumina 1536 GoldenGate 测定法对 383 个多样化的豇豆种质资源和重组自交系群体（RIL）进行 SNP 基因型分析。使用连锁不平衡关联作图，根据 13 个在四个国家进行的实验的表型数据，确定 SNP 与性状的关联，同时作为补充策略的双亲 QTL 作图。我们鉴定了七个位点，其中五个位点表现出与延迟衰老、生物量和籽粒产量之间的多效性（持绿）有关的证据。此外，我们提供了基于三个非洲环境中延迟衰老和籽粒产量的正相关表型值（0.34< r <0.87）和等位基因效应（0.07< r <0.86）的证据，表明豇豆中存在正多效性。在 RIL 和多样化的种质资源中鉴定到的五个假定的持绿 QTL 中的三个，即 Dro-1、3 和 7，分辨率均为 3.2 cM 或以下，这表明这些可能是豇豆标记辅助育种的有价值的目标。此外，早期营养生长延迟衰老与生物量和籽粒产量 QTL 的共定位表明，在豇豆育种中，利用幼苗期的延迟衰老作为开花后干旱耐性的快速筛选工具是可能的。使用含有与最高关联的 SNP 的 EST 序列进行 BLAST 分析，为在密切相关的普通菜豆（Phaseolus vulgaris）和大豆（Glycine max）参考基因组中鉴定的本研究中的基因座提供了基因组背景。
