Sexuality and no apomixis found in crossing experiments with diploid Potentilla argentea

Abstract

Thirty-six crosses between plants of the putative facultative apomictic diploid Potentilla argentea L. (s. 1.) from southern Sweden led to the production of hybrid offspring, as determined by isozyme analysis. Forty-three crosses with diploid P. argentea as mother plants and hexaploid P. argentia L. (s. 1.) or hexaploid P. collina Wib. as pollen donors resulted in normal-looking seeds but with no, or only low, rates of germination. Among the few offspring obtained, two were found to be tetraploid as determined by flow cytometry. Offspring plants with non-hybrid genotypes were occasionally obtained in the crosses, which in all cases could be explained as being due to selfing resulting from incomplete emasculations or unwanted insect pollinations. We conclude that, on the basis of currently available information, diploid Potentilla argentea is not a facultative apomict.