Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2013
Publication Date: 5/21/2013
Citation: Bryant, R.J., Jackson, A.K., Yeater, K.M., Yan, W., Mcclung, A.M., Fjellstrom, R.G. 2013. Genetic Variation and Association Mapping of Protein Concentration in Brown Rice Using a Diverse Rice Germplasm Collection. Cereal Chemistry. http://cerealchemistry.aaccnet.org/doi/abs/10.1094/cchem-09-12-0122-R.
Interpretive Summary: The protein content of rice is often an important characteristic of its nutritional, cooking, and processing quality. Protein is the second most abundant constituent in the rice grain next to starch. A diverse set of rice varieties that originated from several global regions were grown in Arkansas and Texas. They were analyzed for protein content and with 157 DNA markers in order to see if there are any DNA markers associated with protein content. It was found that many rice varieties produce different amounts of protein but this was also dependent on the location where they were grown. Varieties of rice originating from Eastern Europe produced the most protein, while those from Africa produced the least amount of protein. Ten DNA markers located at eight independent gene regions were associated with changes in the amount of protein produced. Five of these markers were located near protein synthesis genes, which could explain the significance of these gene regions on rice protein content. The other five DNA markers are located in novel gene regions, which would require further investigation to see why these regions affect rice protein levels. The genetic markers identified in this study, as well as the diversity of protein content seen in the rice varieties, will assist breeders in developing new rice varieties that have enhanced nutritional value or tailored for applications requiring specific protein amounts in the rice grain.
Technical Abstract: Protein is the second most abundant constituent in the rice grain next to starch. Association analysis for protein concentration in brown rice was performed using a “Mini-Core” collection, which represents the germplasm diversity found in the USDA world rice collection. Protein concentration was determined in replicated trials at two southern U.S. locations and association mapping was performed using 157 genome-wide DNA markers. Protein concentration ranged from 5.4 % to 11.9 % among the 202 accessions. Protein variation due to accessions and accessions x locations interaction were highly significant. Ample variation was seen within each ancestry subpopulation, as well as within the 14 geographic regions where the accessions originated. Accessions from Eastern Europe had the highest level of protein. Ten markers on eight chromosomes were significantly associated with protein concentration. Five markers occurred near known protein precursor genes or QTLs, the other five markers were novel for associations with rice protein concentration. The germplasm and genetic markers identified in this study will assist breeders in developing cultivars having enhanced nutritional value or tailored for applications requiring specific protein concentrations in the rice grain. The research results contribute to the potential discovery of novel rice storage protein pathways in the endosperm.