Genetics of the proportion of peripheral yellow achenes on the capitula of Microseris douglasii strain D37 (Asteraceae, Lactuceae)

Microseris douglasii strain D37 is an interpopulation hybrid. The mature capitula in both parental strains bear three morphologically different kinds of fruits: peripheral hairy achenes (11-5% of all achenes in both strains) followed by a ring of non-hairy yellow achenes and a group of central achenes. The proportions of yellow achenes differ between the strains as a consequence of an allelic difference at a single locus. Lines homozygous for the two alleles of this locus in various recombinant backgrounds have been selected in the hybrid strain, and the influence of environmental and genetic variation, especially for the total number of achenes per capitulum, on the expression of the main gene is demonstrated.