Evaluation of Molecular Markers for Wx Genes and Development of Their Multiplex PCR Systems Based on the Compositions of Wx Proteins for 173 Wheat Cultivars and Lines
Abstract：Quality properties of starch are strongly affected by the compositions of Wx genes in wheat. It is very important to establish stable and efficient methods and systems to detect Wx genes for improvement of quality and rapid evaluation of germplasm resources in wheat breeding programs. In this study, based on the compositions of Wx proteins in 173 wheat (Triticum aestivum L.) cultivars and advanced lines using SDS-PAGE method, the validity of sequence tagged sites (STS) markers for Wx genes were evaluated, and two types of multiplex PCR systems were built up. The results using the SDS-PAGE method showed that twenty of these cultivars and advanced lines were the null Wx-B1 type (11.6%), and one of them was waxy wheat lacked all three Wx proteins (Wx-A1,Wx-B1 and Wx-D1) (0.6%). The results identified by four co-dominant and two dominant STS markers for Wx genes were all identical to those detected by the SDS-PAGE method. Using the six effective molecular markers above, two multiplex PCR systems were established. The multiplex PCRⅠ could simultaneity identify four alleles at Wx-B1 and Wx-D1 loci, and multiplex PCRⅡ were used to detect four alleles in Wx-B1 and Wx-D1 loci. The genotypes of all wheat cultivars and advanced lines identified by the two multiplex PCRs were coincided with those detected by the SDS-PAGE and corresponding single PCR method, respectively. The six STS markers and two multiplex PCRs can be used to increase the efficiency of evaluation and improvement of wheat starch properties in breeding programs.
