Date of Award

Winter 1980

Project Type

Dissertation

Program or Major

Genetics

Degree Name

Doctor of Philosophy

Abstract

The presence of a self-incompatibility (SI) system in the polyploid crucifer, Cheiranthus allionii = Siberian wallflower, was suggested by results of greenhouse screening and confirmed by results of controlled pollinations in the field. Sporophytic control of the system was indicated by a stigmatic barrier to incompatible pollen tube growth, seen in scanning electron micrographs, and by differences in reciprocal cross-compatibilities. Strength of the SI system varied, but no completely self-compatible plants were found. Marked segregation for SI level within self- and cross-progenies of a plant with weak SI suggested that weak SI might be due to a single gene. The strength of the SI system was stable through one generation of selfing. However, no evidence of inbreeding depression on number of seeds per open-pollinated silique was observed. SI levels were independent of open-pollinated fertility levels. The use of heterogeneous material emphasized the advantage of a relative measure of SI level.

Concentrated sucrose solutions (30% w/w) supported pollen germination and tube elongation. Stigma surface components, leached directly into the germination medium, delayed or inhibited germination of incompatible pollen.

This organism provides a tool for the study of SI in heterogeneous populations of a natural polyploid and for the study of interactions between pollen and stigma components.

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