Introgression between the Cultivated Sunflower and a Sympatric Wild Relative,Helianthus petiolaris(Asteraceae)

Abstract

High rates of hybridization and introgression have been reported between the cultivated sunflower and its wild progenitor (both Helianthus annuus), raising concerns that neutral or favorable transgenes might escape and persist in wild H. annuus populations. However, little consideration has been given to the possibility that other wild sunflower species may hybridize with the cultivated sunflower. Here, we estimate the frequency of hybridization and introgression between the cultivated sunflower and Helianthus petiolaris, a closely related wild species whose range almost completely overlaps that of the cultivated sunflower in the central and northern plains and which hybridizes extensively with wild H. annuus. Assays of 21 cultivar‐specific AFLP (amplified fragment length polymorphism) markers in 159 individuals from four sympatric populations of H. petiolaris revealed low rates of introgression, with average marker frequencies per population ranging from 0.006 to 0.026. Twenty‐seven individuals had a hyb...