QTL Analysis For Wheat Spike

Spike length is an important agronomic traits of wheat, the trait is closely associated with the three yield components of wheat, many breeders look the spike length trait as an important index in the process of breeding and Kao Zhong. The main purpose of this study is to make the beginning location of QTL about spike length trait and to lay a foundation for the next step of making fine mapping and marker assisted breeding’ application, at the same time,to provide certain theoretical basis for the study of wheat’s heredity.It has yet to too many studies about the wheat spike length gene. Existing studies have found that the spike length of wheat has higher heritability and heterosis; They have clear difference between different types of spike length or combination of spike length, therefore,applying spike length to select some wheat hybrid combinations is an effective way. At present, the reports of spike length QTL, respectively located in chromosome 1A、1B、2A、2B、2D、3A、3B、4A、4B、5A、5B、5D、6A、6B、7A and 7B.In this study, the QTLs of spike length were analyzed using simple sequence repeat(SSR) markers in a population which consisted of 292 F2 derived from the cross of wheat Gaomai-1(common wheat)×wheat Super small spike(common wheat). Using DNA markers and QTL mapping, and then determine its position in the chromosome and its relationship with other genes and genetic characteristics analysis of spike length, provide the basis for the genetic improvement of yield traits. 9 QTL loci associated with spike length were detected, including 8 additive QTL and 1dominant QTL. Eight QTL additive effect value were positive, contribution rate is 0.16% ~15.26%.The distance between the QTL loci on chromosome 3A and the nearest marker is only 0.58 cM, and the additive effect value of the QTL loci on chromosome 3A is the largest,can explain 15.26% of the phenotypic variation. Therefore, chromosome 3A is likely to contain the main effect genes associated with spike length, the follow-up study should focus on chromosome 3A. Getting the following three conclusions of this research:1. The QTLs associated with spike length detected in this study, only include the additive QTL and the dominance QTL, have no epistatic QTL. Therefore, it can come to an conclusion: the genetic effects of wheat spike length include the additive effect and the dominant effect; In addition, also confirmed the spike length trait of wheat is a quantitativetrait controlled by a composed of multiple effect genes.2. The QTLs detected in this study and predecessors’ researches are not all the same,these differences reflect the complexity of the heredity and expression about the QTLs,closely related to genetic background, also confirmed the QTLs exist combination specificity.3. In this study,the localization of QTL on chromosome 3A belonging to molecular marker interval is same to the results of Yangrui’s study, may be for the same QTL.Therefore, chromosome 3A should contain genes associated with spike length, follow-up experiments should be focused on chromosome 3A.