Gene flow between cultivated sunflower and Helianthus petiolaris (Asteraceae)

GUTIERREZ A; CARRERA A; BASUALDO J; RODRÍGUEZ R; CANTAMUTTO M; POVERENE M

EUPHYTICA

Springer

Lugar: The Netherlands; Año: 2010 vol. 172 p. 67 - 76

0014-2336

Helianthus petiolaris (Asteraceae) native to North America has naturalized in Argentina. The extensive overlapping with sunflower crop regions, the coincidence of life cycles and the common pollinators facilitate interspecific crosses with sunflower, H. annuus var. macrocarpus. To estimate the occurrence of crop-to-wild and wild-to-crop gene flow, off-type plants in progenies of pure stands of  both species flowering in coincidence and the presence of crop alleles in H. petiolaris populations were investigated in 26 wild populations and nine crop fields. Morphological traits and RAPD markers were used to attempt hybrid characterization. Off-type individuals were found in frequencies of 0.5% and 0.3% among crop progenies and wild populations, respectively. Off-type plants showed intermediate values for metric morphological traits and low fertility traits. Some off-type plants could be confirmed as interspecific hybrids, based on the presence of crop alleles. The average frequency of cultivar-marker introgression across the wild populations was very low (0.02). Although observed hybridization rates seem to be low, the extension of crop-wild overlapping in Argentina make hybrid formation a noticeable process. Therefore, diffusion of IMI resistant sunflower varieties and eventually GM varieties would transfer their traits through pollen flow and they would persist in H. petiolaris populations.