甜瓜侧枝相关性状的QTL定位

以甜瓜长侧枝自交系‘TopMark’和短侧枝自交系‘PI353814’为亲本,构建了F_2群体和F_2:3家系。利用92个F_2单株构建了一张包含12个连锁群,353个SSR标记的遗传连锁图谱,覆盖基因组长度为1 565.88 cM,连锁群长度在86.98～186.68 cM,标记间的平均距离为4.44 cM。利用该连锁图谱结合F_2:3家系表型鉴定数据,对甜瓜侧枝相关性状进行定位,共检测到6个QTL,分布在连锁群LGⅠ、LGⅢ和LGⅦ上,LOD值介于2.5067～12.5524之间,可解释9.9242%～48.2348%的表型变异率。其中侧枝总长主效QTLlbtl7.1和侧枝均长主效QTLlbal7.1均位于连锁群LGVⅡ的SSR标记CmSSR17145和CmSSR17293之间,贡献率分别为38.5923%和48.2348%。进一步利用186个F_2:3家系和新开发标记对主效QTL进行了验证,发现侧枝总长主效QTL lbtl7.1定位在SSR标记CmSSR17251和CmSSR17253之间,与两标记的遗传距离分别为2.5和0.5 cM,可解释41.2742%的表型变异,侧枝均长主效QTL lbal7.1被定位在SSR标记CmSSR17238和CmSSR17251之间,距离两标记分别为1.5和0.5cM,可解释55.1739%的表型变异。

QTL Mapping of Lateral Branch Associated Traits in Cucumis melo

To map lateral branch associated QTL in melon，a long lateral branch inbred line‘TopMark’and a short lateral branch inbred line‘PI 353814’was crossed to generate a F2 population and F2:3 line in this study. Using a mapping population containing 92 F2 plants and the SSR markers developed from melon genome，a genetic map containing 353 SSR markers was constructed. The total genetic map covered 1 565.88 cM with an average distance between interval markers of 4.44 cM. The genetic length of these linkage groups ranged from 86.98 cM to 186.68 cM. QTL analysis was carried out by combining the phenotypes of lateral branch related traits in F2:3 lines and the genotyping data，and 6 QTLs for these traits were detected on LGⅠ，LGⅢ and LGⅦ，explaining 9.9242% ~ 48.2348% of total phenotypic variation.Among them，two major QTL lbtl7.1 and lbal7.1 were mapped on chromosome LGVⅡ between markers CmSSR17145 and CmSSR17293，explaining 38.5923% and 48.2348% of the phenotypic variation，respectively. In order to validate these major QTLs，new SSR markers were developed in the candidate region，and an extended population of 186 F2:3 lines were used for QTL mapping. The results showed that the major QTL lbtl7.1 was further mapped between CmSSR17251 and CmSSR17253 markers with a genetic distance of 2.5 cM and 0.5 cM，explaining 41.2742% of the phenotypic variation. Another major QTL lbal7.1 was further mapped between CmSSR17238 and CmSSR17251，with a genetic distance of 1.5 cM and 0.5 cM，respectively，explaining 55.1739% phenotypic variation.