Natural variation in potato sexual reproduction facilitates breeding

Summary

Potato is staple food for 1.3 billion people worldwide. Breeding of new potato varieties, compared to other major food crops, is slow and has yielded little increase in yield. This is primarily due to potato's reproductive characteristics, namely allogamy (cross-pollination) and tetraploidy (having four sets of chromosomes). This thesis describes research into natural genetic variants involved in three aspects of potato reproductive biology: (1) self-compatibility, (2) reduced recombination and (3) unreduced pollen. Self-compatibility enables the fixation of valuable traits into a homozygous state. Unreduced pollen enables to cross improved diploids with tetraploid varieties. Crossover reduction limits exchange of allele during meiosis, so that almost all desired alleles can be passed on to tetraploid offspring with those unreduced gametes. DNA markers have been developed to trace the desired alleles during breeding. With these markers we showed that natural variants underlying these traits were already present in various potato varieties. The combination of these traits into a breeding strategy called "Fixation-Restitution Breeding” promises to facilitates potato breeding and ultimately to deliver improved varieties more quickly and easily.