Genetic Effects Of Dwarfing Gene Rht-5on Agronomic Traits In Common Wheat(triticum Aestivum L.) And Analysis On Its Quantitative Trait Loci

Genes that reduce height without compromising seedling vigor or coleoptile length havegreat potential for wheat improvement. The objective of the present study was to assess thegenetic effects of Rht-5dwarfing gene on agronomic traits in common wheat and identify andlocate QTL alleles of this dwarf gene. Therefore, two tall elite cultivars Ningchun10andJinmai47were crossed with Rht-5donor Marfed M, to produce F1. The F1was allowed to selfto obtain F2seeds. Then, the F2segregation populations and F2:3lines were evaluated alongwith their parents during the winter wheat growing seasons of2010-2011,2011-12and2012-13. The F2populations were genotyped using SSR markers and best tall and dwarf individualswere selected to compose the F2:3lines. Phenotype data were collected on plant height andother agronomic traits. Phenotype and genotype data were merged to QTL mapping. The mainresults were as following:In The cross Ningchun10/Marfed M, analysis of variance in the F2population and F2:3lines indicated highly significant differences among individuals or lines for all of traitsstudied, except for biomass, grain yield and harvest index. In general Rht-5dwarfing genewas associated with a plant height reduction of23.16%, delaying heading date and maturityby4days, increasing the number of fertile tillers plant-1, while reducing the number ofspikelets spike-1and number of grains spike-1by8.94%and26.89%, respectively. In addition,Rht5dwarfing gene was associated with no reduction in final coleoptile length. Earlierheading date, longer spike, more spikelets spike-1, and more grains spike-1could be observedin the dwarf lines when compared to the dwarf parent. Plant height showed positive andhighly significant correlation with peduncle length (0.86), spike length (0.76), number ofspikelets spike1(0.56) and number of grain spike-1(0.42), but negative and highly significantcorrelation with number of fertile tillers plant-1(-0.30) and heading date (-0.71).Analysis of variance in the cross Jinmai47/Marfed showed highly significant differencesamong individuals or lines for all of traits studied. In general, dwarfing gene Rht-5wasassociated with a plant height reduction of25.84%, delaying heading date and maturity by1day, increasing the number of fertile tillers plant-1, while reducing the number of spikeletsspike-1and number of grains spike-1by8.07%and22.31%, respectively. Earlier heading date, longer spike, more spikelets spike-1, and more grains spike-1could also be observed in thedwarf lines when compared to the dwarf parent. Plant height showed positive and highlysignificant correlation with peduncle length (0.23and0.88), spike length (0.86and0.8),number of spikelets spike1(0.76and0.63) and number of grain spike-1(0.56and0.64%), butnegative and highly significant correlation with number of fertile tillers plant-1(-0.64) andheading date (-0.71and0.31).The polymorphic markers data of Jinmai47F2population were used to construct agenetic linkage map. Using composite interval mapping (CIM) analysis,4QTLs weredetected for plant height, heading date, peduncle length and number of grains spike-1andaccounted for up to11.82%,8.02%,10.32%and15.65%of the phenotypic variation,respectively.The results of the present study could provide useful base for proper use of Rht-5dwarfing gene in wheat breeding programs to improve lodging tolerance, yield potential inwheat and increase efficiency of marker assisted selection for agronomic traits.