Date of this Version
Published in Euphytica (2013) 190:65–73. DOI: 10.1007/s10681-012-0777-y
Polyphenol oxidase (PPO) in grain plays a major role in time-dependent discoloration of wheat (Triticum aestivum L.) products, especially fresh noodles. Breeding wheat cultivars with low or nil PPO activity can reduce undesirable product darkening. The low PPO line PI 117635 was crossed to two low PPO wheats, IDO580 and ‘IDO377s’, to determine whether matings between wheats with low levels of grain PPO would result in complementation, such that lines with still lower or nil PPO would be generated. Progeny in a population derived from PI 117635/ IDO580 displayed no variation in PPO activity. In the F3:4 populations derived from PI 117635/IDO377s, and the reciprocal IDO377s/PI 117635, normal distributions of low to high PPO activity were observed. Fieldgrown populations (F3:5; F3:6) derived from IDO377s crosses were analyzed for PPO activity and used to determine whether lines with nil PPO activity were generated. Of 239 lines, 154 were verified to have PPO activity that was not significantly different from the low PPO durum (Triticum turgidum var durum) cultivar ‘Ben’. PCR analysis showed that the populations were fixed for a putative low PPO allele at Ppo-A1. Using markers for Ppo-D1, it was found that the average PPO activity of lines with 490 bp PCR fragments from PPO29 was significantly lower than that of lines with 560 bp fragments from STS01. These results disagreed with that predicted from previous reports for markers for Ppo-D1 alleles. Thus, breeders should exercise caution when making selections using markers for alleles at Ppo-D1, as known markers might predict erroneous phenotypes and genotypes in some wheat backgrounds.