Ravelombola Waltram, Shi Ainong, Huynh Bao-Lam
Department of Horticulture, University of Arkansas, Fayetteville, AR, 72701, USA.
Texas A&M AgriLife Research& Extension, Vernon, TX, 76384, USA.
Hortic Res. 2021 Feb 1;8(1):24. doi: 10.1038/s41438-021-00462-w.
Cowpea is a nutrient-dense legume that significantly contributes to the population's diet in sub-Saharan Africa and other regions of the world. Improving cowpea cultivars to be more resilient to abiotic stress such as drought would be of great importance. The use of a multi-parent advanced generation intercross (MAGIC) population has been shown to be efficient in increasing the frequency of rare alleles that could be associated with important agricultural traits. In addition, drought tolerance index has been reported to be a reliable parameter for assessing crop tolerance to water-deficit conditions. Therefore, the objectives of this study were to evaluate the drought tolerance index for plant growth habit, plant maturity, flowering time, 100-seed weight, and grain yield in a MAGIC cowpea population, to conduct genome-wide association study (GWAS) and identify single nucleotide polymorphism (SNP) markers associated with the drought tolerance indices, to investigate the potential relationship existing between the significant loci associated with the drought tolerance indices, and to conduct genomic selection (GS). These analyses were performed using the existing phenotypic and genotypic data published for the MAGIC population which consisted of 305 F8 recombinant inbred lines (RILs) developed at University of California, Riverside. The results indicated that: (1) large variation in drought tolerance indices existed among the cowpea genotypes, (2) a total of 14, 18, 5, 5, and 35 SNPs were associated with plant growth habit change due to drought stress, and drought tolerance indices for maturity, flowering time, 100-seed weight, and grain yield, respectively, (3) the network-guided approach revealed clear interactions between the loci associated with the drought tolerance traits, and (4) the GS accuracy varied from low to moderate. These results could be applied to improve drought tolerance in cowpea through marker-assisted selection (MAS) and genomic selection (GS). To the best of our knowledge, this is the first report on marker loci associated with drought tolerance indices in cowpea.
豇豆是一种营养丰富的豆类，对撒哈拉以南非洲和世界其他地区人们的饮食有重要贡献。培育更能抵御干旱等非生物胁迫的豇豆品种至关重要。多亲本高世代杂交（MAGIC）群体已被证明能有效增加与重要农艺性状相关的稀有等位基因频率。此外，耐旱指数据报道是评估作物对水分亏缺条件耐受性的可靠参数。因此，本研究的目的是评估MAGIC豇豆群体中植物生长习性、植株成熟度、开花时间、百粒重和籽粒产量的耐旱指数，进行全基因组关联研究（GWAS）并鉴定与耐旱指数相关的单核苷酸多态性（SNP）标记，研究与耐旱指数相关的显著位点之间存在的潜在关系，并进行基因组选择（GS）。这些分析使用了已发表的MAGIC群体的现有表型和基因型数据，该群体由加利福尼亚大学河滨分校培育的305个F8重组自交系（RIL）组成。结果表明：（1）豇豆基因型间耐旱指数存在较大差异；（2）分别有14、18、5、5和35个SNP与干旱胁迫导致的植物生长习性变化以及成熟度、开花时间、百粒重和籽粒产量的耐旱指数相关；（3）网络引导方法揭示了与耐旱性状相关位点之间的明确相互作用；（4）GS准确性从低到中等。这些结果可应用于通过标记辅助选择（MAS）和基因组选择（GS）提高豇豆的耐旱性。据我们所知，这是关于豇豆耐旱指数相关标记位点的首次报道。
