Identifying genetic markers of wheat (Triticum aestivum) associated with flavor preference using a mouse model

Authors: Kiszonas, Alecia; Morris, Craig

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2016
Publication Date: 9/6/2016
Publication URL: http://handle.nal.usda.gov/10113/5493343
Citation: Kiszonas, A., Morris, C.F. 2016. Identifying genetic markers of wheat (Triticum aestivum) associated with flavor preference using a mouse model. Journal of Cereal Science. 71:153-159.

Interpretive Summary: Kernel texture (hardness) is one of the most fundamental ways of classifying and differentiating wheat grain. Hard textured wheat is typically used for bread, whereas soft textured wheat is used for cookies, cakes, pastries, etc. The difference in kernel texture is the result of Puroindoline (Pina and Pinb) genes. Soft wheat is the wild-type with the haplotype of Pinb-a and hard wheat is the mutation of Pinb-b. Whole wheat products provide critical nutrients for human health, though differences in wheat flavor are not well understood. Using the house mouse as a model system, flavor was examined using a two-choice feeding system and the Student’s t statistic. To eliminate the confounding effect of processing, whole grain was used. Because the Clark’s Cream (hard textured) by NY6432-18 (soft textured) is a cross of Pinb-a and Pinb-b haplotypes, the RILs are also a mixture of soft and hard (Pinb-a and Pinb-b) haplotypes. The use of the two check varieties also proved useful in this case of such varied kernel texture and the need to compare the RILs to both texture extremes to evaluate preference. The ability to remove those confounding effects of hardness showed that beyond hardness, there are inherent differences in the way wheat tastes to mice. Future work will focus on using double-haploids of a “Yummy” and a “yucky” parent to further elucidate the genes responsible for a more preferable wheat flavor. Eventually this work seeks to produce whole grain products more palatable for consumers as the public becomes more aware of the importance of whole grain products.

Technical Abstract: Whole wheat products provide critical nutrients for human health, though differences in wheat flavor are not well understood. Using the house mouse as a model system, flavor was examined using a two-choice feeding system and the Student’s t statistic. To eliminate the confounding effect of processing, whole grain was used. The Student’s t statistic used previously identified “Yummy” and “yucky” check varieties. The study took the Student’s t statistic beyond a theoretical measure of flavor preference to use as a phenotype in genetic mapping study. The Clark’s Cream x NY6432-18 RIL population was created in the early 1990s and has been mapped extensively. Both varieties are white wheats; Clark’s Cream has a hard kernel texture and NY6432-18 has a soft kernel texture. The “Yummy” and “yucky” check varieties were soft white and hard white wheats, respectively. A new genetic linkage map was created for this population. Marker-trait association was performed using the Student’s t phenotype from each check. Twenty-two significant associations were found among the two check comparisons. Because mice prefer soft kernel texture over hard, the effect of both the Puroindoline haplotype and the phenotypic expression of kernel texture were used as covariates in further marker-trait association analyses. Twenty-eight markers exhibited significant associations with the Student’s t in the two covariate analyses, with an additional five having significant associations in both the Puroindoline covariate and kernel texture covariate. These five markers show that there is a definitive genetic basis for flavor preference beyond kernel texture. These markers open the door for closer examination of specific genetic regions where the “Yummy” and “yucky” genes are likely to reside. Identifying the flavor genes will allow the development of varieties with more palatability for whole-wheat products.