Peer review

Peer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=0578-1752

【Objective】The aims of this study were to characterize the allelic distribution of PPO genes in Chinese winter wheat cultivars with molecular markers and analyze the association between PPO activity and different PPO alleles for the improvement of PPO activity in marker-assisted selection (MAS).【Method】A total of 311 Chinese wheat cultivars and advanced lines collected from four winter wheat regions (Experiment 1) and common parents in Shandong province (Experiment 2) were tested with the functional markers PPO18, PPO16 and PPO29 for the identification of four allelic variants Ppo-A1a, Ppo-A1b, Ppo-D1a and Ppo-D1b on chromosomes 2A and 2D.【Result】PPO18 could amplify a 685-bp and an 876-bp fragments in the cultivars with the allele Ppo-A1a (high PPO) and Ppo-A1b (low PPO), respectively. Two complementary dominant markers, PPO16 and PPO29, amplified a 713-bp and a 490-bp fragment in the genotypes with Ppo-D1a (low PPO) and Ppo-D1b (high PPO), respectively. The frequencies for Ppo-A1a, Ppo-A1b, Ppo-D1a and Ppo-D1b were 41.8%, 58.2%, 59.8% and 40.2%, in the 311 cultivars and advanced lines, respectively. Significant differences in PPO activities were detected between the genotypes with Ppo-A1a and those with Ppo-A1b (P ＜0.05), and between the genotypes for Ppo-D1a and those for Ppo-D1b. Frequencies of PPO allelic combinations for Ppo-A1a/Ppo-D1a, Ppo-A1a/Ppo-D1b, Ppo-A1b/Ppo-D1a and Ppo-A1b/Ppo-D1b were 27.3%, 14.5%, 32.5% and 25.7%, and highly significant differences in PPO activity were found among the four genotypes (P＜0.05). Ppo-A1a was present as a major allele in middle and low Yangtze Valley winter wheat region and southwestern winter wheat region, with frequencies of 60.7% and 56.0%, respectively, whereas Ppo-A1b was found as a major allele in northern winter wheat region and Yellow and huai facultative winter wheat region, with frequencies of 65.6% and 60.3%, respectively. Ppo-D1a was dominant in northern winter wheat region, Yellow and Huai facultative winter wheat region, middle and low Yangtze Valley winter wheat region and southwestern winter wheat region, with frequencies of 65.6%, 53.6%, 75.0% and 76.0%, respectively.【Conclusion】PPO18, PPO16 and PPO29 were simple and stable functional markers that can accurately discriminate different alleles of PPO genes on chromosomes 2A and 2D, exhibiting high correlation between grain PPO activity and PPO genotypes. The alleles of low PPO activity were dominant in Chinese winter wheat regions. Therefore, employing the PPO markers to test parents and separating generations descendants in wheat breeding programs would help breeder to select the individuals with low PPO activity, accelerating the progress for the improvement of undesirable darkening of end-use product.

Global Wheat Program

Text in English

INT2411|INT3297|INT2411