Characterization Of Over-expressed Bx7 Gene (Bx7^OE) In Chinese And CIMMYT Wheats By STS Markers And Construction Of Genetic Linkage Map In Wheat

Over-expression of the high-molecular-weight glutenin subunit(HMW-GS) Bx7 is highly associated with dough strength of wheat(Triticum aestivum L.) flour.A total of 163 Chinese and CIMMYT wheat cultivars and advanced lines were tested by two STS markers and RP-HPLC to investigate the presence of HMW-GS gene Bx7^OE.The results indicated that the markers TaBAC1215C06-F517/R964 and TaBAC1215C06-F24671/R25515 could amplify a-447 bp and a-844 bp PCR fragments,respectively,in the lines with Bx7^OE,whereas no PCR products were detected in the lines without Bx7^OE.Of the 163 cultivars and lines,specific PCR fragments were amplified in 11 genotypes using by the two markers,indicating the presence of Bx7^OE in these lines,with a frequency of 6.7%.The results obtained by RP-HPLC were consistent with those revealed by STS markers.These two STS markers could be used to detect the Bx7^OE gene in wheat cultivars.Highly dense genetic linkage map is a very important tool for QTL mapping.The 184 DH lines derived from the cross Shanghai3/Catbird×Naxos was used for constructing a genetic linkage map using SSR and DArT markers.The results indicated that 387 markers showed polymorphic markers in these populations and most of them were segregated in accordance with the 1:1 proportion of Mendel's segregation ratio.The final genetic linkage map contained 325 markers including 92 SSRs and 233 DArTs.The linkage map spanned 2777.9 cM with an averaged marker interval of 8.5 cM.The maximum markers and highest density were generated on chromosome 2B,whereas chromosome 4D had the least number of markers and the shortest map length,and the map length each chromosome was 99.7 cM on average.The 277 DArTs markers that had not been mapped previously were localized on the genetic linkage map of wheat in this study.This linkage map is a good foundation for the QTL mapping of agronomic traits and resistance to powdery mildew and Fusarium head blight in the population.