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

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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.