Characterization and Breakdown of Self-Incompatibility in Field Bindweed (Convolvulus arvensis L.)

Abstract

Field bindweed biotypes differ in glyphosate tolerance. Our previous studies have indicated quantitative genetic inheritance of this trait. In order to study the genetics of these differences we must be able to make sexual crosses, however, self-crossing and backcrossing are difficult due to self-incompatibility (SI) in field bindweed flowers. Therefore research was conducted to characterize and overcome the SI system in field bindweed. We determined SI to be of the multiallelic, sporophytic type based on observations of pollen-stigma interaction, and in the pattern of compatibility of F1 backcrosses to the parent biotypes. Pollen in incompatible crosses produced short pollen tubes that failed to penetrate the stigma surface. Backcrossing showed most F1 plants to be compatible with one parent, indicating dominance interactions between alleles. SI in field bindweed was successfully overcome by both bud pollination and heat treatment which exposed plants to 38 degrees C for 2 days before pollination, however, no seeds were produced. Treatment of stigma tips with a hot soldering iron for 2-3 s allowed abundant pollen tube growth from selfed pollen lying in a zone adjacent to the heat-injured area. This method resulted in production of viable selfed seed at rates equal to that observed in outcrosses.