LADOUX, TASHA* and ELIZABETH A. FRIAR. Rancho Santa Ana Botanic Garden, 1500 N. College Ave., Claremont, CA, 91711. - Self-Incompatibility in Ipomopsis tenuifolia (Polemoniaceae).
Results from reciprocal diallele crossing experiments among a parental
generation, as well as a full-sib family of 34 sibs suggests a novel,
complex system of self-incompatibility (SI) in Ipomopsis
tenuifolia (Polemoniaceae). Thirteen individuals from a population
in Baja California, Mexico, were randomly chosen as parental plants.
All crosses among parental and F1 individuals were successful,
including backcrosses to parents, with the exception of three
non-reciprocal crosses in the parental generation. All selfs were
incompatible. Pollen tube growth was observed within selfs inside the
ovary. The lack of incompatibility among sibships and backcrosses, as
well as the complete lack of selfing success may suggest either a
multi-locus gametophytic SI system or late-acting SI. Pollen tube
growth within the ovary is more consistent with late-acting SI. Thus
far, this study does not clarify the discrepancy between previous
results of crossing studies in Polemoniaceae. Levinís (1993) results
suggested single-locus gametophytic SI in Phlox drummondii,
whereas Goodwillie (1997) found sporophytic SI with linear dominance
in Linanthus parviflorus. The SI system for Polemoniaceae
appears to be more complex than previously thought.
Key words: Ipomopsis tenuifolia , Self-Incompatibility