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

大豆[Glyine max(L.)Merrill]是全球最大的油籽作物。为了提高种子产量，大豆育种工作主要集中在优良适应亲本与其他优良适应亲本的杂交上。植物导入(PI)在大豆育种中的应用一直受到限制，尽管它们有可能对产量和其他性状做出有利贡献，并增强遗传多样性。我们最近的研究利用加拿大和中国的大豆优良品系杂交培育的群体来确定产量的数量追踪基因座(QTL)，即大环境通用(QTLU)或大环境特异性(QTLSP)。这使得解剖与植物适应不同环境有关的基因组区域成为可能。提高产量的等位基因往往是由不适应亲本贡献的，但产量QTL在育种群体中差异表达的基本原理有待进一步研究。DNA甲基化可以通过抑制和沉默基因来调节基因的表达，而不会对潜在的DNA序列造成任何改变，而且这种基因修改可以在减数分裂和有丝分裂中遗传。这一建议的目的是通过研究DNA甲基化在产量QTL表达中的作用，继续我们对植物适应的遗传基础的研究。在北美和中国的三个大环境中进行的多地点田间试验中，来自两个中国x加拿大种群的种子样本将接受DNA甲基化分析。这项研究有望有助于理解QTLU和QTLSP的性质，因为它与植物对大环境的适应有关，这将有助于从PI中战略性地导入新的等位基因到适应的大豆种质库中。

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.