Inheritance and reproductive consequences of floral anthocyanin deficiency in Silene dioica (Caryophyllaceae).

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• Flower color is one of the most important traits for pollinator attraction. However, natural plant populations often harbor rare flower color variants resulting from mutations in biochemical pathways for floral pigment production. It is unclear how such mutations can persist because they can affect not only pollinator visitation but also plant fertility and performance.• We collected rare white-flowered (anthocyanin-deficient) and common pink-flowered morphs of Silene dioica from natural populations in Switzerland. First- and second-generation hybrids between pink and white morphs, as well as backcrosses toward white morphs were produced, and the proportion of white-flowered offspring was determined. We compared seed siring ability and seed production between morphs using hand pollination experiments. Moreover, we scored the transfer of pollen analogues (fluorescent dyes) in a 50:50 array of the two morphs.• The proportions of white-flowered plants in the offspring of our crosses were consistent with more than one recessive mutation as the cause of floral anthocyanin deficiency and further suggested a role of maternal effects for flower color. Seed siring ability and seed set did not differ significantly between pink and white morphs. Pollen transfer occurred preferentially within morphs.• Overall, our results imply that the white morph of S. dioica likely is caused by recessive mutations that do not impair reproduction. However, as this flower color polymorphism led to assortative mating in our experiment, it may represent standing genetic variation with the potential to contribute to evolutionary divergence.