Genetic and epigenetic bases for adaptation to mega-environments in soybean

大豆适应大环境的遗传和表观遗传基础

• 批准号: RGPIN-2014-06376
• 负责人: Rajcan, Istvan
• 金额: $ 2.19万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567765
• 关键词: Genetic; epigenetic; bases; adaptation; mega

Crop improvement relies on continued use of genetic variation in plants and a lack of variation may impede further progress from plant breeding. Genetic variation can be found in breeding populations but also in gene banks or in nature across many regions of the world such as centres of origin or diversity for crop plants. However, only a fraction of existing variation in many crop plants has been used by plant breeders mainly due to an inherent lack of adaptation of exotic sources to target breeding environments. Soybean is a crop in which 90% of the genetic variation in North American soybeans is derived from as few as 35 ancestors. In contrast, vast amount of genetic variation exists in China as the centre of origin for soybean and may be available for use by plant breeders. In our previous NSERC Discovery grants we have identified a number of universal and ME specific Quantitative Trait Loci (QTL[U] and QTL[SP]) for yield and agronomic traits of which some were unique. Alleles for high yield have been often contributed by the PI (exotic) parent in each respective ME demonstrating the potential for introgressing new positive alleles from exotic germplasm. Both minor and major QTL alleles were contributed by the Chinese parent in the Canadian ME, the majority of them being QTL[U] across all three ME: Canada, northern U.S. and China. In addition, QTL[U] explained a greater amount of variation and were distributed across fewer linkage groups than the QTL[SP]. Universal QTL also exhibited fewer interactions and of smaller magnitude than the specific ones. Eighty-six percent of QTL[U] were associated with other agronomic or seed quality traits but acted as either QTL[U] or QTL[SP] for the yield related traits (Palomeque et al. 2009a and 2009b). We want to explore the underlying reasons for differential QTL expression that affect plant adaptation across different environments. DNA methylation is known to cause epigenetic changes that result in altered gene expression. Differential gene or QTL expression may be one of the reasons for difficulties in identifying exotic sources as potential parents for hybridization with adapted cultivars because their true genetic potential may be impacted (or masked) by epigenetic factors. In order to increase the use of plant germplasm from China to further improve soybeans in Canada, we will study the role of DNA methylation in the genomic regions that have been associated with seed yield as the ultimate measure of plants' adaptation to a new environment. An improved understanding of the role that DNA methylation plays in the expression of QTL for yield across different mega- and macro-environments will allow for the development of strategies for enhanced used of exotic germplasm. This in turn may lead to an increase in genetic gain from selection for seed yield in plant breeding populations and accelerate progress from and economic impacts of plant breeders' efforts. A continuous increase in seed yield of crops such as soybean will address the need for producing adequate food supplies for an increasing human population around the world.

作物改良有赖于继续利用植物的遗传变异，而缺乏变异可能会阻碍植物育种的进一步进展。遗传变异可以在育种种群中找到，也可以在基因库或世界许多地区的自然界中找到，例如农作物的起源中心或多样性。然而，许多作物的现有变异中只有一小部分被植物育种者利用，这主要是因为外来来源固有地缺乏对目标育种环境的适应。大豆是一种作物，北美大豆90%的遗传变异来自仅35个祖先。相比之下，中国作为大豆的起源中心，存在着大量的遗传变异，可能会被植物育种家利用。在我们以前的NSERC发现拨款中，我们已经确定了一些通用的和ME特定的数量性状基因座(QTL[U]和QTL[SP])，用于控制产量和农艺性状，其中一些是独一无二的。在各自的ME中，高产等位基因通常由PI(外来)亲本提供，表明有可能从外来种质中导入新的阳性等位基因。在加拿大代谢能中，主要和次要的QTL等位基因都是由中国亲本贡献的，其中大多数是加拿大、美国北部和中国三个ME中的QTL[U]。此外，与QTL[SP]相比，QTL[U]解释了更多的变异，并且分布在更少的连锁群上。与特定QTL相比，通用QTL表现出较少的互作和较小的幅度。86%的QTL[U]与其他农艺性状或种子质量性状有关，但在产量相关性状中充当QTL[U]或QTL[SP](Palomeque等人)。2009a和2009b)。我们想要探索影响植物在不同环境中适应的不同QTL表达的潜在原因。众所周知，DNA甲基化会引起表观遗传变化，从而导致基因表达的改变。基因或QTL的差异表达可能是难以识别外来来源作为与适应品种杂交的潜在亲本的原因之一，因为它们的真实遗传潜力可能受到表观遗传因素的影响(或掩盖)。为了更多地利用中国的植物种质资源，进一步改良加拿大大豆，我们将研究DNA甲基化在与种子产量相关的基因组区域中的作用，作为植物适应新环境的最终措施。更好地理解DNA甲基化在不同大环境和宏观环境中表达产量的QTL中所起的作用，将有助于制定加强利用外来种质的策略。这反过来可能导致在植物育种群体中从种子产量选择中获得更多的遗传收益，并加快植物育种者的努力的进展和经济影响。大豆等作物种子产量的持续增加将满足为世界各地日益增长的人口生产充足粮食供应的需要。