Investigating the Genetic Basis of Leaf Economic Traits in Cultivated Sunflower (Helianthus annuus L.)

Cultivated sunflower is an important crop species, grown worldwide for its high seed oil content, as well as for confectionery and decorative purposes. Despite strong selection during domestication and cultivation for fast growth and high yield, cultivated sunflower retains a considerable amount of genetic diversity correlating with breeding history type and agronomic use. Genetic associations have been found for important traits such as flowering time and whole-plant branching patterns. However, little is known regarding the genetic architecture of important physiological traits involved in plant growth and carbon allocation. In this study, we used an association mapping population of cultivated sunflower, Helianthus annuus L., to assess variation in multiple leaf traits, including photosynthetic rate, stomatal conductance and water-use efficiency. Plants were grown in a common garden growth chamber environment and traits were measured at the juvenile stage.  Though no significant genetic associations were detected, a considerable amount of leaf trait variation exists among cultivars, with significant correlations among multiple traits. Future studies investigating trait diversification during the domestication process of crop species can provide insight into responses to long-term selection pressures, and inform breeding efforts for sunflower.