Distribution Of Dwarf Genes And Their Association With Agronomic Traits In Bread Wheat From The Yellow And Huai Wheat Region Germplasm

Identification of distribution of dwarf genes and their influence on agronomic traits in bread wheat could contribute to reasonable use of dwarfing genes and could provide valuable information for wheat breeding program.Different molecular markers at 6 Rht loci(Rht1,Rht2,Rht4,Rht8,Rht9 and Rht12)were used to detect distribution of dwarf genes in 246 common wheat from the Yellow and Huai valleys,respectively.Totals of 10 agronomic traits including plant height,spike length,peduncle length,spikelet number per spike,flag leaf length,flag leaf width,kernel number per spike,kernel length,kernel width and thousand-kernel weight were investigated for three years and were analyzed their relationship with the Rht loci.The results showed that six dwarfing genes showed an extensive distribution in the Yellow and Huai valley,especially for the Rht1 and Rht2 genes,none of the six loci dwarfing gene only had four.Analysis of association of the 6 dwarfing genes with the 10 agronomic traits in bread wheat showed that at Rht1 locus cultivars with Rht1-B1 a and Rht1-B1 b alleles did not show significant difference for plant height and other traits.At Rht2 locus,cultivars with Rht2-D1 b had a significantly lower plant height,peduncle length and higher thousand-kernel weight than Rht2-D1 a over three years,suggesting that Rht2-D1 b is the superior allele.Excluding the effect of Rht1 and Rht2 genes due to their strong influence on agronomic traits,the four loci of Rht4,Rht8,Rht9 and Rht12 had also an important effect on different agronomic traits in wheat cultivars from the Yellow and Huai valley.Among the four loci,Rht4 played an important role in plant height and thousand-kernel weight and thus Rht4-B1 b is the relatively superior allele;Rht8 had an important effect on spike length,peduncle length,flag leaf length,and thousand-kernel weight and thus Rht8-D1 b is the relatively superior allele;Rht9 had an important effect on plant height,spike length and thousand-kernel weight and thus Rht9-A1 a is the relatively superior allele;Rht12 had an important effect on spikelength and thousand-kernel weight and thus Rht12-A1 a is the superior allele.Further analysis showed that Rht2 showed the most important effect on plant height and thousand-kernel weight among the six loci and the following is Rht4.Four(Rht1,Rht2,Rht8 and Rht12)of the six loci showed significant effect on thousand-kernel weight,and Rht2 showed the most significant effect on thousand-kernel weight among the four loci.According to different genotype combination with Rht2 and Rht1 loci were analyzed,Rht1-B1a/Rht2-D1 b had most widely distributed in wheat cultivars from the Yellow and Huai valley,Rht1-B1b/Rht2-D1 a and Rht1-B1b/Rht2-D1 b had less distributed,Rht1-B1a/Rht2-D1 a had least distributed;cultivars with Rht1-B1a/Rht2-D1 b and Rht1-B1b/Rht2-D1 b had a significantly lower plant height and higher thousand-kernel weight than Rht1-B1a/Rht2-D1 a and Rht1-B1b/Rht2-D1 a.Analysis of the distribution of the six superior alleles in cultivars from different stages indicated percentages of the superior alleles generally increased from early historical cultivars,recent historical cultivars to modern cultivars in the Yellow and Huai valley,and especially 82.9% of modern cultivars had Rht2-D1 b.It is conclude that the dwarf genes at the six loci mainly showed important effects on plant height and thousand-kernel weight,and some of the genes showed significantly effects on spike length,flag leaf length and kernel size.Analysis of the distribution of dwarf genes at the 6 different loci in wheat cultivars from the Yellow and Huai valley and their impact on the agronomic traits could find out the superior alleles in views of agronomic traits so that they could be more reasonably utilized in wheat breeding program and this study could also provide valuable information for high yield wheat breeding.