|Nilthong, Somrudee Onto -|
|Baenziger, Stephen -|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 16, 2012
Publication Date: August 8, 2012
Repository URL: http://handle.nal.usda.gov/10113/55927
Citation: Nilthong, S., Graybosch, R.A., Baenziger, S.P. 2012. Inheritance of grain polyphenol oxidase (PPO) activity in multiple wheat (Triticum aestivum L.) genetic backgrounds. Theoretical and Applied Genetics. DOI 10.1007/s00122-012-1947-y. Interpretive Summary: High levels of the plant enzyme polyphenol oxidase are undesirable in products produced from hard white wheats. Hard white wheat products such as “white whole grain breads” are gaining favor in the U.S. marketplace. Hard white wheats also are the wheat of choice in select export markets, especially in Asia, where they are used to produce a variety of fresh noodle products. High levels of polyphenol oxidase in the grain, however, render U.S. hard white wheats undesirable and at a disadvantage competing in the Asian markets against wheats from Australia. In an effort to develop hard white wheats with low levels of polyphenol oxidase, controlled matings were produced between wheats having different forms of the genes producing this enzyme. From the crosses, wheat breeding lines with very low or even near-zero levels of polyphenol oxidase were generated. The zero level lines carry a new gene that might eliminate production of the enzyme. It was also observed that crosses between lines with high levels of the enzyme actually can generate lines with much lower levels, indicating different genes control high levels in different lines. The materials generated in this study will be used to develop hard white winter wheats adapted to the northern Great Plains that lack polyphenol oxidase, potentially stimulating demand for the produce of U.S. wheat producers.
Technical Abstract: Grain polyphenol oxidase (PPO) activity can cause discoloration of wheat (Triticum aestivum L.) food products. Five crosses (PI 117635/Antelope; Fielder/NW03681; Fielder/Antelope; NW07OR1070/Antelope; NW07OR1066/OR2050272H) were selected to study the genetic inheritance of PPO activity. STS markers, PPO18, PPO29 and STS01 were used to identify lines with putative alleles at the Ppo-A1 and Ppo-D1 loci conditioning low or high PPO activity. ANOVA showed significant genotypic effects on PPO activity (P < 0.0001) in all populations. The generations and generation X genotype effects were not significant in any population. A putative third (null) genotype at Ppo-A1 (no PCR fragments for PPO18) was discovered in NW07OR1066 and NW07OR1070 derived populations, and these had the lowest mean PPO activities. Results demonstrated both Ppo-A1 and Ppo-D1 loci affect the kernel PPO activity but the Ppo-A1 has the major effect. In three populations contrary results were observed to those predicted from previous work with Ppo-D1 alleles, suggesting the markers for Ppo-D1 allele might give erroneous results in some genetic backgrounds or lineages. Results suggest selection for low or null alleles only at Ppo-A1 is sufficient to allow development of low PPO wheat cultivars.