A model of triploid endosperm evolution driven by parent-offspring conflict

The parental investment in angiosperms comprises the endosperm, a nutrient reserve that is used during seed development. The endosperm contains genes from both parents. The most common endosperm form is the 3n Polygonum -type with more maternal genetic influence than paternal, i.e. with two maternal nuclei and one paternal nucleus. The evolutionary original state is thought to be a diploid endosperm with equal influence of the parents. We focus on the evolution of the triploid endosperm and show that a gene for triploid endosperm would have an initial advantage in a population of diploid endosperm type plants, and increase to fixation. We assume that endosperm amount is controlled by endosperm genes. Then a gene causing triploid endosperm will increase the influence of the mother plant on parental investment. The production of endosperm with two copies of the maternal genes will modify the inheritance of endosperm amount and cause an increased production of seeds.