Use of 2x Tuberosum haploid-wild species hybrids to improve yield and quality in 4x cultivated potato

Abstract

The 4x × 2x(FDR) breeding method utilizes 2x (Tuberosum haploid × 2x relatives) potato hybrids which produce 2n pollen by an FDR mechanism. About 80 percent of 2x parental heterozygosity and most epistasis is transmitted intact to 4x progeny. Six 2x hybrids of Tuberosum haploid-Solanum tarijense (5) or S. berthaultii (1) were factorially mated as males to four cultivated 4x Tuberosum clones. Twenty-three 4x × 2x families were evaluated along with the four 4x parents and seven 4x × 4x (inter-Tuberosum) families in three environments for tuber yield, specific gravity, chip color, vine maturity, tuber uniformity and general tuber appearance. Compared with the 4x parents and 4x × 4x families, the 4x × 2x families had greater yield, higher specific gravity, better general tuber appearance, but darker chip color. The 4x × 2x families were not significantly different from 4x×4x families for vine maturity and they were not significantly different from 4x parents (clones) for tuber uniformity. Mean heterosis of 4x × 2x families over the 4x parent ranged from 5.2 to 127.1 percent. Combining abilities were estimated for 2x and 4x parents used in 4x × 2x crosses. Effects of males (2x GCA) were significant for chip color, general tuber appearance and vine maturity. Female effects (4x GCA) were significant for specific gravity, general tuber appearance and vine maturity. GCA variances exceeded SCA variances for all traits except yield and tuber uniformity. For these traits, the effect of 4x×2x(FDR) crosses overcame differences in male and female effects. Superior 2x parents were identified for light chip color (P100-6, P133-7, P100-1); good general tuber appearance (P94-1, P127-3); and early vine maturity (P100-6, P100-1, P133-7).