Genetic Diversity Of Wx Gene In Chinese Wheat Landraces And European Varieties

Waxy protein is also named granule-bound starch synthese(GBSS), and its gene site is called Wx. Expression of Wx gene directly control the synthesis of amylose. Amylose content of hexaploid wheat is high correlated with Waxy protein, wheat varieties with null Wx-B1 protein have low amylose content and good noodle attribute. Therefore, it is very essential for improvement of starch character and noodle quality to study of waxy protein in wheat.A total of 1739 Chinese common wheat(Triticum aestivum, AABBDD) landraces were screened for the Wx gene mutations by using two STS, one SSR and one specific markers. The results showed that three accessions were Wx-A1 mutants, twenty-five were Wx-B1 mutants, and three were Wx-D1 mutants. These mutants were also certified by SDS-PAGE of their Waxy proteins. These results also indicated that these molecular markers were useful tools to detect wheat Wx gene mutants.In addition, a total of 384 European varieties were also screened for the Wx gene mutations using the same molecular markers. 19 accessions were Wx-B1 mutants, no Wx-A1 or Wx-D1 mutants were detected. These results showed-that European materials were mainly Wx-B1 mutants. Importantly, comparison of Wx gene mutants in Chinese. wheat landraces and introduced varieties from Europe showed that Wx gene mutants in Chinese wheat landraces was more frequency than that in European varieties.Mutants with good agronomic characters from Chinese wheat landraces, such as Hongmangrnai, Zhuganqing, Heshangtou and Huisancao, etc.were crossed each other, and 4 double recessive homozygotes at Wx-A1 and Wx-B1 were detected in F₂ population by molecular markers. They were crossed with Zhengrnai9023 and Zhengmai9405. However, the primer for Wx-D1 gene site is a dominant marker, so the homozygotes can not be. efficiently identified. In this study, 4 plants which were recessive homozygotes at Wx-A1 gene site and 3 plants which were recessive homozygotes at Wx-B1 gene site were detected successfully, but these 7 plants may be heterozygosis at Wx-D1 gene. The double recessive homozygotes will be obtained in next generation.