A new method for potato breeding: the -Fixation-Restitution- approach
Conventional potato breeding relies on heterozygous tetraploid parents. During meiosis the genetic quality of these parents disperse across gametes, leading to a segregating offspring with very few desirable individuals. True seed F1 hybrid breeding is promising, but requires high investments in development of suitable material, while success is not yet guaranteed.
The project aims to solve the most important limitation of traditional breeding. With self-compatible diploids we can reach fixation of many beneficial traits, but without the need of 100% homozygosity for F1 hybrid uniformity. This alleviates the loss of vigour and fertility due to inbreeding depression. With 2n gametes by First Division Restitution (FDR) all fixed alleles are transferred to tetraploids. This method circumvents the many unsolved issues with inbreeding depression, combining ability and heterotic groups.
The project will deliver the material and technology for an innovative potato breeding scheme. Specific components that will be delivered are (WP1) unique breeding material to breeding companies; (WP2) DNA markers to guarantee self-compatibility of diploids; (WP3) DNA markers to guarantee 2n FDR gametes; (WP4) Expand the diploid gene pool with new primary dihaploids that contribute trait alleles currently unavailable at the diploid level; (WP5) Identify recombinant diploids with trait alleles linked in cis-configuration (coupling phase); (WP6) Develop and disseminate progenitors with self-compatibility, 2n-gametes, homozygous for a multitude of pyramided disease resistance genes in a series of ideotype backgrounds (fresh market, starch, export, crisps, French fries).
The project is appropriate and necessary because it addresses the key bottleneck in potato breeding. Potato is a food crop of global importance and Dutch breeding companies have a leading position to release new varieties. Conventional potato breeding is a slow and inefficient numbers game. The inception of true seed F1 hybrids is an excellent innovation, but the technology readiness level is less obvious and technology access is limited by patents. This project opened a middle road combining the strength of genetic fixation with the strengths of conventional propagation of seed potatoes.
(WP1) vigorous and fertile, self-compatible diploids have been shared with breeding companies in 2020 and ongoing breeding efforts will be conducted in 2021 onwards.
(WP2) Development of DNA markers to guarantee self-compatibility was achieved in 2020.
(WP3) In 2021 we aim to unravel the inheritance of 2n FDR gamete formation and to identify DNA markers for marker assisted breeding.
(WP4) In 2020 and 2021 new primary dihaploids will be developed that bring valuable resistance genes (late blight / nematodes / wart disease etc) from tetraploid to diploid germplasm.
(WP5) On chromosome 5, 9 and 11 we will force closely linked resistance genes from trans into cis configuration (coupling phase) by recombination events (2021-2023).
(WP6) Develop and disseminate progenitors with self-compatibility, 2n-gametes, homozygous for a multitude of pyramided disease resistance genes in a series of ideotype backgrounds (fresh market, starch, export, crisps, French fries).