| Abstract |
White-grained wheat varieties have an advantage that powder dullness is small and milling yield is high. They have, however, a tendency to be less tolerant to pre-harvest sprouting than red-grained wheat varieties. Pre-harvest sprouting in wheat represents a major constraint to the production of high-quality grain. Thus, it is desired to develop white-grained varieties with high tolerance against pre-harvest sprouting. Red-grained varieties have red seed coats. The ‘R loci' for seed coat color are located one each in the A, B, and D genomes in wheat, which is an allohexaploid crop. Red coat color is dominant and white coat color is a recessive trait. Seed coat color is a Mendelian inheritance trait. If at least one R locus is red grain type, the seed coat color will be red. In addition, the phenotype of the grain color is not identified until one generation later because seed coat is a maternal tissue. Therefore, genetic markers are useful in wheat breeding not only to decide the R loci genotypes of the parents' lines but also to select white-grained segregants efficiently from siblings at the seedling stage.
This report introduces a simple, labor-saving method for the genotyping of wheat seed coat color genes, Tamyb10-A1, Tamyb10-B1, and Tamyb10-D1. This method consists of two multiplex PCRs per sample. Multiplex PCR 1 was carried out with five types of primers for genotyping of Tamyb10-A1. Then, multiplex PCR 2 was carried out with four types of primers for genotyping of Tamyb10-B1 and Tamyb10-D1. This is more labor-saving than the method reported previously by Himi et al. (2011), which required five PCRs for each sample.
First, Tamyb10s in four varieties were analyzed by the previous method and this new method. The results showed the same genotypes detected by the two methods. Next, two leading varieties from Hokkaido, “Yumechikara” and “Kitahonami”, with unknown Tamyb10s genotypes, were analyzed by multiplex PCRs. The results showed that their genotypes were R-A1a／R-B1b／R-D1b and R-A1b／R-B1a／R-D1b, respectively. This new method contributes to selecting white-grained segregants from backcross populations of a white-grained line × “Zenkojikomugi” (a red- grained variety).
Genotypes of 16 red-grained varieties are shown as examples. The information is useful in making the three genes R-A1a／R-B1a／R-D1a match to select white-grained lines from siblings with high tolerance against pre-harvest sprouting in wheat breeding.
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