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上位效应与小麦产量性状杂种优势

2017-10-21来源:莱肯生物
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      提高小麦产量、满足日益增长的粮食需求是全球农业面临的重要挑战。杂种优势利用是小麦增产的有效途径。阐明杂种优势的遗传机理是深化杂种优势利用的基础,因此科学家提出了显性假说、超显性假说和上位性假说的杂种优势三大假说。
      近日,来自德国莱布尼茨植物遗传与作物研究所的遗传学家通过改良的数量遗传模型研究普通小麦杂交群体的杂种优势遗传机理。该群体包括1604个杂交种及其15个父本和120个母本。这些亲本均是来自中欧的优异种质,并具有高密度的SNP标记。通过考察该群体在11个不同生态环境下的产量指标,累计约400万个数据点的结果显示杂交种平均高出中亲值10%,意味着需要15年的小麦育种进程,可见杂交小麦增产潜力显著。进一步,利用改良的数量遗传模型进行全基因组预测和关联作图分析,结果表明上位效应在控制小麦产量性状的过程中扮演重要角色,且其作用要大于显性效应。然而上位效应在小麦杂种优势中的作用给小麦杂种优势利用带来挑战,因为试图培育优异的单交组合以及持续利用显性效应的难度巨大。

Nature Genetics,  16 October 2017
 A quantitative genetic framework highlights the role of epistaticeffects for grain-yield heterosis in bread wheat

Authors
YongJiang, Renate H Schmidt, Yusheng Zhao & Jochen C Reif
Department of Breeding Research, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.

Abstract
Increasing wheat yield is a key global challenge to producing sufficient food for agrowing human population. Wheat grain yield can be boosted by exploiting heterosis, the superior performance of hybrids compared with midparents. Here we present a tailored quantitative genetic framework to study the genetic basis of midparent heterosis in hybrid populations derived from crosses among diverse parents. We applied this framework to an extensive data set assembled for winter wheat. Grain yield was assessed for 1,604 hybrids and their 135 parental elite breeding lines in 11 environments. The hybrids outperformed the midparents by 10% on average, representing approximately 15 years of breeding progress in wheat, thus further substantiating the remarkable potential of hybrid-wheat breeding. Genome-wide prediction and association mapping implemented through the developed quantitative genetic framework showed that dominance effects played a less prominent role than epistatic effects in grain-yieldheterosis in wheat.

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