萝卜肉质根糖含量相关性状的关联位点分析

Analysis of loci related to sugar content traits in radish taproot

【目的】挖掘与萝卜肉质根糖含量相关性状密切关联的SSR位点,为萝卜品质改良提供参考。【方法】以134份萝卜品种构成的自然群体为材料,在成熟期对萝卜肉质根中的果糖、葡萄糖、蔗糖、可溶性总糖含量和甜度值进行连续3年(2015-2017年)的表型鉴定,利用SPSS 20.0软件对上述5个糖含量性状进行相关性分析,选用156对SSR引物进行群体扫描,利用PowerMarker V3.25软件分析134份萝卜品种的遗传多样性,应用Structure 2.3.4软件分析包含134份萝卜品种自然群体的遗传结构,利用Tassel 3.0软件对SSR标记与糖含量相关性状进行关联分析。【结果】134份萝卜品种的糖含量相关性状在群体中变异较广,甜度值的广义遗传力最高(60.10%),其次是葡萄糖(53.79%)、可溶性总糖(48.51%)和果糖(40.73%),蔗糖的广义遗传力最低(30.67%)。用156对SSR引物从134份萝卜品种中共检测到349个多态性位点,多态性信息量(PIC)为0.106~0.864,多样性指数为0.112~0.877。群体结构分析表明,134份萝卜品种可分为2个亚群,其中亚群1包含46个萝卜品种,对应表1中1~46号品种;亚群2包含88个萝卜品种,对应表1中47~134号品种;且亚群分类与地理来源无明显对应关系。在P≤0.01阈值条件下,检测到与5个糖含量相关性状关联的位点61个,其中与葡萄糖含量关联的位点16个,与甜度值关联的位点13个,与蔗糖含量关联的位点13个,与可溶性总糖含量关联的位点10个,与果糖含量关联的位点9个,单个位点的表型变异解释率为5.19%~16.29%。【结论】获得61个与萝卜肉质根糖含量相关性状显著关联的SSR位点,其中有14个标记位点具有“一因多效”现象,能同时被2个或2个以上性状检测到。

【Objective】This study mined SSR loci associated with sugar content traits in radish taproot to improve radish quality.【Method】Five sugar related traits including glucose content,fructose content,sucrose content,total sugar content and sweetness index of 134 radish varieties were investigated for three years(2015-2017).Correlation analyses between sugar-related traits were performed by SPSS 20.0 software.All radish varieties were genotyped using 156 simple sequence repeats(SSRs)before PowerMarker V3.25 was used to estimate genetic diversity of these 134 radish varieties and Structure 2.3.4 was used to assess genetic population structuring.Finally,genome-wide association study was performed using sugar phenotypic data of 134 radish cultivars and one set of genotypic data including 156 SSRs to identify loci associated with sugar content using Tassel 3.0.【Result】The values of sugar content related traits had a wide range among the 134 varieties.Sweetness index had the highest broad heredity(60.10%),followed by glucose content(53.79%),total sugar content(48.51%),and fructose content(40.73%),while sucrose content had the lowest broad heredity(30.67%).A total of 349 loci were detected by 156 SSR markers in the 134 radish cultivars with PIC values of 0.106 to 0.864 and gene diversity coefficients of 0.112 to 0.877.The population structure analysis revealed that the 134 radish cultivars can be divided into two subpopulations.Subpopulation 1 included 46 radish cultivars and subpopulation 2 contained 88 radish cultivars.A total of 61 SSR loci associated with sugar-related traits were detected,including 16 loci related to glucose content,13 loci related to sweetness index,13 loci related to sucrose index,10 loci related to total sugar content,and 9 loci related to fructose content(P≤0.01).These loci explained 5.19%to 16.29%of phenotypic variance.【Conclusion】A total of 61 significant loci were detected and 14 loci were pleiotropic,which were simultaneously detected by 2 or more sugar-related traits.