Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: 6/20/2005
Publication Date: 7/5/2005
Citation: McClung, A.M., Chen, M., Bockelman, H.E., Bryant, R.J., Yan, W., Fjellstrom, R.G. 2005. Genetic markers reveal novel genes which control rice cooking quality. Texas Rice, Highlighting Research in 2005. http://beaumont.tamu.edu/eLibrary/Newsletter/2005_Highlights_in_Research.pdf. pp. X-XI.
Technical Abstract: Rice molecular markers have been developed in the gene (Waxy) that controls grain amylose content and the gene (Alk) that controls alkali spreading value. Both of these factors are considered the major determinants of rice cooking quality and texture. This set of markers is now being routinely used by US breeding programs to expedite the development of improved rice cultivars that meet rice cooking quality standards as determined by the US rice industry. For the first time, these markers have been used to characterize a subset of the rice germplasm collection that is maintained by the USDA-ARS National Small Grains Collection. There are over 20,000 accessions in the rice collection and about 1600 of these have been chosen as a representative core subset. These were grown in Stuttgart, AR during 2002 for plant trait evaluation and then sent to the USDA-ARS Rice Research Unit in Beaumont for genetic marker analysis. Several markers associated with the Waxy and Alk genes were evaluated. Fourteen different forms (alleles) of the Waxy gene were identified and 8.2% of the accessions were found to be mixtures. Of the Waxy alleles identified, eight were considered rare alleles, being found in less than 5% of the accessions. Five of these (CT 12, CT 13, CT 15, CT 21, and CT 22) were new alleles, not observed in our previous, smaller surveys. These new alleles were identified from a diversity of regions from around the world. These results demonstrate that molecular marker evaluation provides an accurate method for characterizing world germplasm that is not influenced by the location where the seed was produced; markers reveal sample mixtures that may be obscured when traditional trait evaluation methods are used; and markers clearly distinguish unique alleles that may be useful for discovering novel cooking and processing qualities in rice.