Association studies of salinity tolerance in sunflower provide robust breeding and selection strategies under climate change

Authors: McNellie, James; MAY, WILLIAM - Agriculture And Agri-Food Canada; RIESEBERG, LOREN - University Of British Columbia; Hulke, Brent

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Increased salinity of farmland in the Great Plains has been a notable effect of climate change. A large portion of cropland in the region has salinity levels above the tolerances of many crops, which result in complete crop failure and the proliferation of weeds that are salinity tolerant. Sunflower is considered to be moderately tolerant of salinity, and its deep roots can assist with driving salts deeper into the soil profile as part of a crop rotation. The goal of this work was to determine whether breeding programs have germplasm resources that perform well under both saline and non-saline soil conditions, and to develop tools (especially DNA markers) that can track genes providing salinity tolerance. In total, 14 gene-associated loci were linked to salinity tolerance and improved performance under both saline and non-saline conditions. In addition, breeding strategies are discussed that leverage these resources.

Technical Abstract: Phytotoxic soil salinity is a global problem, and in the northern Great Plains and western Canada, salt accumulates on the surface of marine sediment soils with high water tables under annual crop cover, particularly near wetlands. Crop production can overcome saline-affected soils using crop species and cultivars with salinity tolerance along with changes in management practices. This research seeks to improve our understanding of sunflower (Helianthus annuus) genetic tolerance to high salinity soils. Genome-wide association was conducted using the Sunflower Association Mapping panel grown for two years in naturally occurring saline soils (2016 and 2017, near Indian Head, Saskatchewan, Canada), and six phenotypes were measured: days to bloom, height, leaf area, leaf mass, oil percentage, and yield. Plot level soil salinity was determined by grid sampling of soil followed by kriging. Three estimates of sunflower performance were calculated: 1) under low soil salinity (<4 dS/m), 2) under high soil salinity (> 4 dS/m), and 3) plasticity (regression coefficient between phenotype and soil salinity). Fourteen loci were significant, with one instance of co-localization between a leaf area and a leaf mass locus. Some genomic regions identified as significant in this study were also significant in a recent greenhouse salinity experiment using the same panel. Also, some candidate genes underlying significant QTL have been identified in other plant species as having a role in salinity response. This research identifies alleles for cultivar improvement and for genetic studies to further elucidate salinity tolerance pathways.