Genome-Wide Association Mapping of Growth Response to Flooding Stress in Sunflower (Helianthus annuus L.)

Sunflower, as a globally important oil crop, whose growth and production are limited by flooding stress. However, the understanding of how growth is affected by flooding stress is lacking. In this study, a large scale phenotyping experiment was performed to evaluate the variation in growth responses to flooding stress in a diverse collection of cultivated sunflower accessions. Flooding responses in multiple traits, such as shoot biomass reduction, chlorosis and hypocotyl hypertrophy were collected as an estimate for flooding resistance. The genetic architecture underlying the growth responses upon exposure to flooding stress was investigated by performing a genome-wide association (GWA) mapping on the different growth related phenotypes. No locus with major effect was found to be associated with differential growth responses to flooding stress, while many promising peaks of association with small phenotypic effects were identified. Many candidate genes underlying the associations were suggested. Further functional analyses of allelic variation in candidate genes will provide insights into the genetic basis of variation in flooding resistance in sunflower.