title: The inheritance of modifiers conferring self-fertility in the partially self-incompatible perennial, Campanula rapunculoides L. (Campanulaceae).
abstract: The role of partial self-incompatibility in plant breeding system evolution has received little attention. Here, we examine the genetic basis of modifiers conferring self-fertility in the creeping bellflower, Campanula rapunculoides L. (Campanulaceae), a partially self-incompatible herb. A survey of 35 individuals from two natural populations indicates that 45% of them are strongly self-incompatible, 40% intermediately self-incompatible, and 15% weakly self-incompatible and that some plants show a strong breakdown in self-incompatibility over floral age. We generated 101 F1 families by random crossing among 31 parental plants and estimated the heritability of self-fertility in day 1 and day 4 female-phase flowers, the genetic correlation between day 1 and day 4 self-fertility, and the coefficient of additive genetic variance of self-fertility. We use linear regression and data from additional crosses to examine whether there are significant maternal effects in the expression of self-fertility. We use Fain's test to determine if a major gene influences self-fertility and, finding no evidence, use data from additional crosses on an F2 generation to estimate the mean number and dominance of genes conferring self-fertility. These analyses indicate that the heritability (h2) of self-fertility is 0.24 in day 1 female-phase flowers and 0.44 in day 4 flowers, self-fertility is primarily additive but shows some recessive effects, and self-fertility is estimated to be controlled by four genetic factors. In addition, we have evidence that there may be maternal effects for self-fertility, especially for weakly self-incompatible plants. The significance of these results in the context of mating system evolution is discussed.
authors.affiliation: Department of Biology, The Pennsylvania State University, University Park 16802, USA. sgood@miranda.ecologia.unam.mx
authors.forename: Sara V
authors.initials: SV
authors.lastname: Good-Avila
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Stephenson
mesh_terms: D005075:Biological Evolution; D029422:Campanulaceae / Q000145:classification / Q000235:genetics* / Q000502:physiology; D003433:Crosses, Genetic; D005298:Fertility; D018392:Genomic Imprinting