Genetic Characterization of Maximilian Sunflower for the Development of a Locally Adapted Perennial Grain Oilseed

Abstract

Maximilian sunflower (Helianthus maximiliani Schrad.), a crop wild relative of sunflower (Helianthus annuus L.), has been identified as a species of interest for the development of a perennial oilseed crop. Knowledge of the diversity, the potential for crop development, and genomic resources of this crop wild relative is limited. To facilitate its use in breeding programs, a baseline characterization of locally adapted germplasm is required to develop informed breeding strategies. Individuals were collected from nine sites in southern Manitoba, Canada, and characterized for phenotypic and genotypic divergence to estimate traits of interest for the implementation of a breeding program in Maximilian sunflower. Genotype‐by‐sequencing was used to characterize population genetic parameters and identify candidate single nucleotide polymorphisms (SNPs) associated with phenotypic divergence and environmental differences between collection sites. Candidate SNPs associated with frost‐free period, temperature during the primary vegetative growth period, elevation, soil CaCO3 equivalent, days to anthesis and capitulum size were identified and may be useful for the improvement of H. maximiliani and crop species related to cultivated sunflower. Associations between temperature, population structure, and overall plant size were also identified, suggesting phenotypic divergence across a local temperature gradient. The sampled Maximilian sunflower populations exhibited a high degree of polymorphism, low levels of inbreeding, and a highly heterozygous genome at the local scale, traits that favor the establishment of locally adapted germplasm pools. There appears to be sufficient variation to make selections for agronomic traits in local germplasm of Maximilian sunflower to support its development as a perennial oilseed.