Makumbi Dan, Assanga Silvano, Diallo Alpha, Magorokosho Cosmos, Asea Godfrey, Worku Mosisa, Bänziger Marianne
International Maize and Wheat Improvement Center (CIMMYT), PO Box 1041-00621, Nairobi, Kenya.
Monsanto Company, 1506 Hwy 69 Suite 100, Waco, NE 68460, USA.
Crop Sci. 2018 Jul-Aug;58:1492-1507. doi: 10.2135/cropsci2017.09.0531. Epub 2018 Jun 7.
Maize ( L.) yield in sub-Saharan Africa (SSA) is low because of both abiotic and biotic constraints, and limited availability or use of improved seed in some areas. This study was conducted (i) to estimate combining ability and heterosis among seven stress-tolerant populations, and (ii) to assess diversity among the populations and the relationship between diversity and heterosis. Twenty-one hybrids developed from diallel crosses of seven populations, parents, and two checks were evaluated in 10 optimal and 11 stressed environments (drought, low N, and random stress) in Kenya, Ethiopia, Uganda, and Zimbabwe for 2 yr. Analysis II of Gardner and Eberhart showed that variety and heterosis were significant for grain yield (GY) under optimal and managed stress, and across environments. Heterosis accounted for most of the variation for GY among populations under optimal conditions (67%) and drought stress (53%), which suggested the importance of dominance in inheritance of GY under these conditions. Genetic distance (GD) among populations ranged from 0.328 to 0.477 (mean = 0.404). The correlation between GD and heterosis was low ( = 0.14-0.40) in all environments. The simple sequence repeat (SSR) marker-based and GY-based clustering of parental populations showed similar patterns, with three populations distinct from the rest, suggesting significant differentiation of allelic variation in these three populations. The SSR-based diversity and phenotypic analysis results should be useful in defining breeding strategies and maintaining heterotic patterns among these populations.
由于非生物和生物胁迫,以及撒哈拉以南非洲(SSA)部分地区改良种子的供应或使用有限,玉米(L.)产量较低。本研究旨在:(i)估计7个耐胁迫群体之间的配合力和杂种优势;(ii)评估群体间的多样性以及多样性与杂种优势之间的关系。由7个群体、亲本和2个对照的双列杂交产生的21个杂交种,在肯尼亚、埃塞俄比亚、乌干达和津巴布韦的10个最佳环境和11个胁迫环境(干旱、低氮和随机胁迫)中进行了为期2年的评估。Gardner和Eberhart的分析II表明,在最佳和可控胁迫条件下以及不同环境中,品种和杂种优势对籽粒产量(GY)均具有显著影响。在最佳条件下(67%)和干旱胁迫下(53%),杂种优势占群体间GY变异的大部分,这表明在这些条件下显性在GY遗传中的重要性。群体间的遗传距离(GD)在0.328至0.477之间(平均 = 0.404)。在所有环境中,GD与杂种优势之间的相关性较低( = 0.14 - 0.40)。基于简单序列重复(SSR)标记和亲本群体的GY聚类显示出相似的模式,其中三个群体与其他群体不同,表明这三个群体中等位基因变异存在显著差异。基于SSR的多样性和表型分析结果有助于确定育种策略并维持这些群体间的杂种优势模式。