Distribution of Genes Related to Plant Height,Kernel Weight and Disease Resistance among Wheat Cultivars from Major Countries

Using the molecular markers for dwarfing genes(Rht-B1b and Rht-D1b)and kernel weight related genes(TaCwi-A1a and Hap-6A-A) and Lr34/Yr18/Pm38,the distributions of these genes were detected among 745 cultivars from 21 major wheat-growing countries.The results indicated that:(1) The frequencies of Rht-B1b and Rht-D1b in 745 cultivar were 42.1% and 28.7%,respectively,varying much in different wheat-growing countries.Generally,cultivars from the same country usually carried only one of Rht-B1b and Rht-D1b,frequencies only from Italy and Australia were higher for both Rht-B1b and Rht-D1b,which in high latitude areas such as Canada and Russia were lower due to less requirement for plant height.(2) TaCwi-A1a allele was widely distributed in 21 countries with a total frequency of 78.4%,and cultivars from different countries possessed all higher frequency of TaCwi-A1a except for Japan(50.0%),Germany(45.3%) and Chile(48.8%).The 29.3% of cultivars carried Hap-6A-A allele at TaGW2-6A locus,mainly distributing in spring and weak winter wheat,whereas Hap-6A-G was mainly present in winter and strong winter cultivars.(3) The 22.1% of cultivars had Lr34/Yr18/Pm38 allele,with higher frequency in USA(18.5%),Ukraine(28.6%),Russia(26.1%),Iran(20.0%),Turkey(34.8%),Hungary(50.0%),Bulgaria(38.9%),Romania(87.0%),Japan(80.0%),Canada(34.6%) and Australia(44.6%).(4)The molecular markers CWI 21 and CWI 22 for TaCwi-A1 can well differentiate TaCwi-A1a and TaCwi-A1b alleles,while the CAPS marker of TaGW2-6A can also be used for kernel weight selection due to its ability of discriminating Hap-6A-A and Hap-6A-G with great accuracy and repeatability.The information is very crucial for use of exotic germplasm in Chinese wheat breeding program.