Oil concentration and fatty-acid profile of naturalized Helianthus annuus populations from Australia.
Although wild annual sunflower (Helianthus annuus L.) is indigenous to North America, it has been both inadvertently and intentionally introduced into other countries, such as Australia, where it has become naturalized. Prior to this research, there were no collections of naturalized H. annuus from Australia in the USDA National Plant Germplasm System gene bank. The possibility exists that naturalized Australian populations may contain distinct traits, such as oil content and fatty-acid composition, differing from their North American progenitors due to the different environments, diseases, and insect-pest complexes. The objective of this study was to collect naturalized H. annuus populations from the five states of Australia and to analyze them for oil content and fatty-acid composition. Fifty-six populations were collected throughout the broad distributional range of this species and then analyzed for oil content and fatty-acid composition. The mean oil content of the H. annuus populations was 28%, ranging from a low of 19% to a high of 31%, similar to populations of this species in its native North American habitats. Fatty-acid profiles were also similar for North American wild populations, Australian naturalized populations, and improved cultivars. Oil concentration of hybrids can be rapidly increased to acceptable levels by backcrossing with cultivated sunflower. Based on this fact, there should be little concern about the relatively low oil content of these naturalized populations when they are used as a source of other unique traits for cultivated sunflower improvement.