桃2个endo-PG基因序列SNPs的遗传多样性及其与果实黏离核性状的关联分析

Polymorphism of SNPs in two endo-PG genes and its association analysis for flesh adhesion trait in peach

【目的】解析桃果实黏离核性状的分子机制。【方法】以不同黏离核性状的45份桃野生资源、地方品种和育成品种为试材,采用第2代测序技术鉴定2个通过连锁分析得到的、串联重复的endo-PG基因在45份种质中的SNPs(single nucleotide polymorphisms)信息;继而采用GLM(Generalized Linear Models)和MLM(Mixed Linear Models)模型进行关联分析,鉴定与黏离核性状关联的SNPs。【结果】在ppa006839m和ppa006857m这2个endo-PG基因内共鉴定到98个SNPs,平均1 SNPs/59 bp。在少数位点上,离核和黏核种质的SNPs多态性存在差异,但整体多样性水平差异不显著,暗示这2个endo-PG基因倾向于中性进化。根据98个SNPs位点信息构建的系统发育树能够反映这些种质的进化关系,即光核桃、甘肃桃最为原始,山桃其次,普通桃最为进化。GLM关联分析结果表明,在ppa006839m基因的内含子3区存在一个与黏离核性状显著关联的位点,对表型变异的解释率为21.1%,但经Bonferroni多重检验校正后,该位点并无统计学意义。而MLM模型的关联分析并没有检测到显著关联位点。【结论】研究结果虽然没能解释果实黏离核的分子机制,但暗示ppa006839m可能与该性状存在更为紧密的联系。同时,研究结果也为果实黏离核性状的分子标记辅助育种奠定基础。

【Objective】 The aim of this paper was to study the mechanisms of flesh adhesion trait in peach(Prunus persica L). 【Method】 Forty-five accessions including wild resources, landraces and improved varieties with different flesh adhesion character were used as the material. The SNPs(single nucleotide polymorphisms) in two concatenated copies of the endopolygalacturonase gene(endo-PG) in peach reported previously through linkage analysis were screened based on next generation sequencing technology. Association analysis using GLM(Generalized Linear Models) and MLM(Mixed Linear Models) models were done between these SNPs and flesh adhesion trait. 【Result】 The results show that 98 SNPs were identified in two PG genes, ppa006839m and ppa006857m, the average 1 SNPsper59 bp. In few sites,the SNPs polymorphisms were different between cling stone and free stone group. But the overall diversity of the difference was not significantly indicated the two endo-PG genes suffered a process of balancing selection. A phylogenetic tree constructed based on the SNPs can reflect the history of peach evolution. It means that from P. mira and P. kansuensis to P. davidiana, so far as to P. persica, the degree of evolution was increased gradually. Association analysis using GLM model showed that a locus existed in intron 3 of ppa006839m gene significantly associated with the flesh adhesion trait. It can account for 21.1% phenotypic variance. After with Bonferroni multiple test correction, the P value was below the threshold. And the association analysis with MLM draw no obvious singnal.【Conclusion】 Although the results of this study do not explain the molecular mechanisms of flesh adhesion clearly, it indicated that ppa006839m may be linked with the trait more closely. Meanwhile, the findings also lay a foundation for marker-assisted breeding of flesh adhesion in peach.