Molecular Tagging Of Low-tillering Genes Cul2.b And Lnt1.a In Barley

Tillering has a considerable role in the formation of yield in cereal crops, for the reason that it is the basic feature of the development of cereal crop and the major indicator of seedling. The decrease of tiller number in a plant results in the increase of grain number per spike, and the decline in ineffective tillering. Therefore, understanding the principle of tillering in cereal crops and its relationship to other agronomic traits is valuable to improve the grain weight per spike. This study analyzed the genetic effects of low-tillering plant by comparing two barley low-tillering mutants GSHO531 and GSHO1984 with North American cultivar barley Bowman. Meanwhile, the low tillering genes cul2.b and lntl.a were tagged by using SSR markers. The following results were obtained.1. The agronomic characters investigation and genetic analysis of low-tillering materials (GSHO531 and GSHO1984) and Bowman were carried out among their Fi and F2 populations. The results showed that except the tiller number, the agronomic characters of GSHO531 and GSHO1984 such as plant height,1000 grain weight, and spike length were significant higher than those of Bowman. The tiller number of Bowman×GSHO1984 F1 is significantly larger than other materials. The heterosis of Bowman×GSH0531 F1 is higher than Bowman×GSHO1984 F1. Correlation analysis demonstrated that tiller number and plant height, panicle length of GSHO531 were significantly correlated to each other. Genetic analysis indicated that the few tiller of GSHO531 was controlled by one major nucleus gene with influence of environment factors, meanwhile the phenotype variation was determined by environment and genetic factors. The few tiller of GSHO531 was controlled by one major nucleus gene with several minor genes.2. Genetic analysis showed that the tillering character of GSHO531 was controlled by a recessive gene cul2.b. Thus, SSR analysis and bulked sergeant analysis (BSA) were used to identify SSR markers linked to the gene cul2.b, which was located on the long arm of chromosome 6. Seven microsatellite markers BmagO613, GBM1212, GBM1319, GBM1423, Bmag0807, BmagO378 and BmagOOO3 on 6H were linked to the gene cul2.b. Among of them, GBM1212 and BmagO613 were closely linked to the cul2.b with the genetic distance of 12.7 cM and 13.2 cM, respectively. The linkage map of gene cul2.b was: Centromere-BmagO378-GBM1423-GBM1319-GBM1212-cul2.b-BmagO613-BmagO807-BmagO003.3. Genetic analysis showed that the tillering character of GSHO1984 was controlled by a recessive gene lntl.a. One microsatellite markers GBM1043 on barley chromosome 3 was closely linked to the gene lntl.a with the genetic distance of 7.8 cM.