The reproductive biology of the potato and its implication for breeding

Haploidy, 2n gametes, synaptic mutants, stylar barriers, endosperm barriers , Endosperm Balance Number (EBN) and its relationship to 2n gametes, stylar barriers and disomic genetics are a part of the reproductive biology of po tato. Also all are tools for isolation and preservation of a species identi ty. Haploidy and 2n gametes allow for interploidy gene transfer. Parallel s pindles and synaptic mutants permit the transfer of entire parental genomes intact and are powerful tools in potato breeding. Stylar barriers provide a mechanism for interspecific isolation via unilateral incompatibility. Inc ongruity has also been invoked. Endosperm barriers have been discussed in t erms of EBN which requires a 2 maternal:1 paternal ratio in the endosperm f or successful seed development. Genetic models suggesting three unlinked ge nes in a threshold-like system and a two gene system have been proposed. A relationship may exist between EBN and stylar barriers. The use and manipul ation of 2n gametes, stylar barriers and EBN have been used effectively in germplasm transfer from species to cultivated potato.