Transcriptome-wide approach to address lower seed protein content in soybean grown in Western Canada

Soybean is an important agronomic crop in Canada with widespread uses in human consumption, animal feed, and biotechnology. The capacity to fix nitrogen gives soybean an important role in sustainable agricultural practices by reducing the need for nitrogen fertilizers. Adapting Canadian soybean agriculture to changing climate conditions is necessary to produce an adequate crop yield with acceptable levels of seed protein. The Canadian Grain Commission has reported lower seed protein from soybeans grown in western Canada compared to eastern Canada, regardless of genotype. This project will uncover key genes underlying differences in seed protein content across Canada.

Using a transcriptome-wide approach, we identify differences in expression of genes contributing to seed protein content, and to study the effect of environmental variation on geographically-dependent gene expression (West vs East). Three groups of genes are being investigated; seed protein and oil biosynthesis genes, stress response genes, and genes that code for regulatory proteins capable of influencing gene expression. Ten soybean lines ranging low to high in seed protein are growing in four locations across western and eastern Canada from 2018-2021. RNA sequencing is used to establish a large, high-quality expression library for all samples across all years. Differential expression used together with gene ontology and novel transcript discovery are key bioinformatic tools for determining candidate genes. Results to date have identified potential candidate genes underlying the differences in seed protein and oil content. This research offers novel information for geographically-tailoring Canadian soybean and developing allele-specific markers to breed high protein soybean cultivars.