Construction of homozygous diploid potato through maternal haploid induction

Reinventing the tetraploid potato into a seed-propagated, diploid, hybrid potato would significantly accelerate potato breeding. In this regard, the development of highly homozygous inbred lines is a prerequisite for breeding hybrid potatoes, but self-incompatibility and inbreeding depression present challenges for developing pure inbred lines. To resolve this impediment, we developed a doubled haploid (DH) technology, based on mutagenesis of the potato DOMAIN OF UNKNOWN FUNCTION 679 membrane protein (StDMP) gene. Here, we show that a deficiency in StDMP allows the generation of maternal haploids for generating diploid potato lines. An exercisable protocol, involving hybridization, fluorescent marker screening, molecular and flow cytometric identification, and doubling with colchicine generates nearly 100% homozygous diploid potato lines. This dmp-triggered haploid induction (HI) system greatly shortens the breeding process and offers a robust method for generating diploid potato inbred lines with high purity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42994-022-00080-7.

Virus-Induced Gene Silencing in Diploid and Tetraploid Potato Species

Potato is the world's fourth largest food crop and a vegetatively propagated model polyploid plant. To facilitate genomic studies in potato, here we describe detailed protocols to silence genes in both diploid potato Solanum bulbocastanum and tetraploid potato cultivars such as Maris Bard, Arran Pilot, Ancilla, and Serrana using tobacco rattle virus (TRV)- or potato virus X (PVX)-induced gene silencing (VIGS) system, respectively. The established VIGS system represents an efficient and powerful approach for functional analysis of genes involved in growth, development, metabolism, and responses to biotic and abiotic stresses in potato.

QTL mapping in diploid potato by using selfed progenies of the cross S. tuberosum × S. chacoense

Usually, mapping studies in potato are performed with segregating populations from crosses between highly heterozygous diploid or tetraploid parents. These studies are hampered by a high level of genetic background noise due to the numerous segregating alleles, with a maximum of eight per locus. In the present study, we aimed to increase the mapping efficiency by using progenies from diploid inbred populations in which at most two alleles segregate. Selfed progenies were generated from a cross between S. tuberosum (D2; a highly heterozygous diploid) and S. chacoense (DS; a homozygous diploid clone) containing the self-incompatibility overcoming S locus inhibitor (Sli-gene). The Sli-gene enables self-pollination and the generation of selfed progenies. One F2 population was used to map several quality traits, such as tuber shape, flesh and skin color. Quantitative trait loci were identified for almost all traits under investigation. The identified loci partially coincided with known mapped loci and partially identified new loci. Nine F3 populations were used to validate the QTLs and monitor the overall increase in the homozygosity level.