Genetic Control of Self-Incompatibility in Centromadia (Hemizonia) Pungens Subsp. Laevis (Madiinae, Asteraceae)

The presence of se lf-incompatibility was tested in Centroma dia pun gens subsp. laevis and (he gene tic basis of the se lf-incompatib ility respon se was ex plored using crossing stud ies. We performed full d iallel c ross ing experiments amo ng 10 ind ividuals from one natural population and four F, families . We observed a strong se lfinco mpaubility resp onse in a ll indi viduals tested . with a significant d ifference in seed se t between se lfed and outcrosse d maii ngs . Most pairw ise rnat ings amo ng parental plants were co mpatib le. with so me nonreciprocall y incom pat ible matin gs (i .e.. the rnatin gs we re suc cessfu l in one direction . but not the other), and only one recipro cally incompatible mating. The full diallel cross ing s tudies among sibs in the four F, families showed two major compatibility c lasses. Th ese res ults are consistent with a sing leloc us spo rophytic se lf-incompatibility system in this spec ies .