Study of haplotype variation and association of microsatellite alleles on chromosome 4B of bread wheat with some agronomic traits

The aim of this study was to determine the haplotype groups and their relationship with phenotypic traits in order to obtain the alleles associated with desirable agronomic characteristics in bread wheat. For this purpose, 34 local bread wheat genotypes belong to the Middle East region along with Chinese Spring variety (reference genotype) were cultivated in the form of augmented design and evaluated based on their 12 phenotypic traits. The results of descriptive statistics showed that awn length and day to flowering had the highest and lowest phenotypic coefficient of variation respectively. Ten microsatellite markers were used to investigate the haplotype variation of QTLs associated with phenotypic traits located on wheat chromosomes 4B. The mean of polymorphic alleles, polymorphic information content (PIC) and resolving power (RP) were 4.5, 0.29 and 1.58, respectively. The genotypes were classified into 21 haplotype groups according to the allelic comparison with the reference genotype on chromosome 4B. In order to investigate the relationship between traits and markers, analysis of variance was performed on the basis of completely randomized design with unequal numbers of replications for each marker. In general, of the 12 traits studied, there was a statistically significant relationship for four traits. According to the results of microsatellite markers on chromosome 4B, there was a linkage between grain width, number of grains per spike and flag leaf width with Xgwm888-4B marker, number of spikelets per spike with Xgwm891-4B marker, grain width and number of grains per spike with Xgwm898-4B marker. For the three phenotypic traits, a specific allele was simultaneously introduced to Xgwm888-4B marker. If the breeders is interested in genotype selection that simultaneously have three desirable characteristics such as more grain width and more number of grain per spike, as well as increase of leaf area index through flag leaf width, they can use an allele-specific (199 bp) of Xgwm888-4B marker.