Location: Vegetable Crops Research
Project Number: 5090-21220-006-025-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2019
End Date: Aug 31, 2024
Objective:
1. Determine the genetic basis and environmental stability of self-fertility.
2. Develop self-fertile, diploid germplasm that captures the allelic diversity of tetraploid cultivars.
3. Create inbred lines that are fixed (homozygous) for key traits. Hypothesis: Inbreeding diploid potatoes will lead to the fixation of traits that have remained variable in tetraploid potatoes.
4. Develop agronomic and economic frameworks for incorporating True Potato Seeds (TPS) into the potato production system and assessing its impacts.
Approach:
1. We will create segregating populations and phenotype them for fertility and self-compatibility. Evaluations will be carried out in multiple environments to determine the stability of expression of self-fertility. Populations will be genotyped and used for quantitative trait loci (QTL) mapping of the fertility traits.
2. Elite tetraploid clones from each of the major germplasm groups in the U.S. potato commodity market will be selected from across the U.S. public breeding programs to establish the germplasm base for a coordinated diploid breeding effort. Whole genome resequencing of these founders will be performed based on the potato pan-genome. Tetraploids will be pollinated with a haploid inducer, and true dihaploids (= diploid haploids) among the offspring will be identified. Skim sequencing of confirmed dihaploids will be used to impute the whole genome sequence from the parents and assess allelic diversity. Sequence data will be combined with phenotypic data (e.g., plant vigor, tuber yield and type, flowering and fertility) for the dihaploids to select a set of diploid founders. These founders will be pollinated with the self-fertile clones characterized in Objective 1 to create populations for inbreeding in Objective 3.
3. We will carry out a two-year breeding cycle that utilizes selection in greenhouse and field environments to allow for two generations in each year. In each generation, plants will be genotyped by skim sequencing, and whole-genome sequence imputed based on the complete genomes of the founders. Clones will also be genotyped with a low-density single- nucleotide polymorphism (SNP) panel linked to major genes for Potato Virus Y(PVY) resistance, golden nematode resistance, and late blight resistance, to select inbred lines that are fixed for these traits. The recurrent selection populations will be used in selection mapping to identify deleterious alleles, linkage mapping based on the phenotype and sequence data, and genomic-estimation of breeding values to select the best F3 clones for intermating.
4. Studies will be conducted to examine methods to produce and grow TPS. Then, we will evaluate ways in which to produce a tuber seed crop from TPS. Several methods will be considered, including greenhouse-based mini-tuber production, transplanting seedlings for field production, and direct seeding in the field. In collaboration with Cooperator, we will examine the potential impacts of TPS on the potato industry.
