The role of DNA methylation in determining genetic adaptation of soybean to mega-environments

大豆[Glycine max（L.）梅里尔]是世界上产量最大的油料作物。为了提高种子产量，大豆育种努力主要集中在优良适应的亲本系与其他优良适应的亲本系的杂交上。植物引种（PI）在大豆育种中的应用一直受到限制，尽管它们有潜力对产量和其他性状以及增强遗传多样性做出有利贡献。我们最近的研究使用了加拿大和中国优良大豆品系杂交开发的群体，以确定产量的数量跟踪位点（QTL）为大环境通用（QTLU）或大环境特异性（QTLSP）。这使得解剖与植物适应不同环境相关的基因组区域成为可能。产量性状QTL在育种群体中的差异表达规律有待于进一步研究。DNA甲基化可以通过基因的抑制和沉默来调节基因表达，而不会引起潜在DNA序列的任何改变，并且这种基因修饰可以在减数分裂和有丝分裂中遗传。本研究的目的是通过研究DNA甲基化在产量QTL表达中的作用，继续探索植物适应性的遗传基础。来自两个中国x加拿大种群的种子样本将在北美和中国的三个大型环境中进行多地点田间试验，并进行DNA甲基化分析。这项研究将有助于理解QTLU和QTLSP的性质，因为它涉及到植物对大环境的适应，这将有助于从PI到适应大豆种质库的新等位基因的战略渐渗。

Soybean [Glycine max (L.) Merrill] is the largest oilseed crops produced worldwide. To increase seed yield, soybean breeding efforts have been primarily focused on the crossing of elite adapted parental lines with other elite adapted parental lines. The use of plant introductions (PI) in soybean breeding has been limited despite their potential to contribute favorably to yield and other traits as well as enhanced genetic diversity. Our recent research used populations developed by crossing Canadian and Chinese elite soybean lines to identify quantitative trail loci (QTL) for yield as either mega-environment universal (QTLU) or mega-environment specific (QTLSP). This has allowed the dissection of genomic regions associated with plant adaptation to different environments. The yield-enhancing alleles were often being contributed by the PI (unadapted) parent, however, further investigation into the underlying principles of differential expression of yield QTL in breeding populations in warranted. DNA methylation can regulate gene expression through the suppression and silencing of genes without causing any alterations to the underlying DNA sequence, and such gene modifications can be meiotically and mitotically inherited. The objective of this proposal is to continue our research into genetic basis for plant adaptation by investigating the role of DNA methylation in the expression of yield QTL. Seed samples from two Chinese x Canadian populations grown in multi-location field trials in three mega-environments in North America and China will be subjected to DNA methylation analysis. This research is expected to contribute to the understanding of the nature of QTLU and QTLSP as it relates to plant adaptation to mega-environments, which would facilitate a strategic introgression of novel alleles from PIs into the adapted soybean germplasm pool.