Objective Distribution of the genes related to brown discoloration-causing polyphenol oxidase (PPO) in wheat cultivars of Qinghai Province was investigated by molecular marker analysis.

Method Genomic DNA was extracted from the leaves of 288 wheat cultivars from Qinghai at the two-leaf stage. Functional markers PPO18, PPO16, and PPO29 were applied for genotyping the Ppo-A1 and Ppo-D1 loci, with the 685 bp and 876 bp amplicons corresponding to the Ppo-A1a and Ppo-A1b alleles, respectively, and the 713 bp and 490 bp amplicons corresponding to the Ppo-D1a and Ppo-D1b alleles, respectively. PCR products were separated by 1.5% agarose gel electrophoresis, and the distribution frequencies of each allele and allelic combinations were statistically analyzed.

Result In the cultivars, the allelic frequency of Ppo-A1a was 25.3% and that of Ppo-A1b 20.8%, while those of Ppo-D1a and Ppo-D1b 58.0% and 19.8%, respectively. The appearing frequencies of the combinations Ppo-A1b/Ppo-D1a, Ppo-A1a/Ppo-D1b, Ppo-A1a/Ppo-D1a, and Ppo-A1b/Ppo-D1b were 13.2%, 6.9%, 14.6%, and 8.3%, respectively.

Conclusion The Ppo-A1 locus was largely characterized by the high-PPO-activity Ppo-A1a allele with the frequency of 25.3%, whereas Ppo-D1 was mainly represented by the low-activity Ppo-D1a allele of 58.0%. Of the biallelic combinations, the medium-activity genotype Ppo-A1a/Ppo-D1a of 14.6% and the low-activity genotype Ppo-A1b/Ppo-D1a of 13.2% dominated the genetic profile. The molecular information on the Qinghai wheat cultivars could facilitate the breeding of varieties with reduced PPO activity to enhance the quality and extend shelf life of the flour made from them.