517份玉米种质容重与其他品质性状相关性分析及候选基因挖掘

Correlation analysis of test weight and other quality traits and candidate gene mining in 517 maize germplasms

【目的】玉米Zea mays籽粒容重是国家玉米区试标准中品质性状的重要指标之一,是一个复杂的数量性状,目前其影响因素和调控机制尚未完全解析。淀粉、蛋白质、脂肪等品质性状是影响容重的重要因素,但其与容重的关系仍存在争议。本研究旨在阐明容重与其他品质性状之间的相关性,揭示容重的调控机制。【方法】测定以浙江省地方玉米种质资源为主要构成的517份玉米种质的容重,粗淀粉、粗蛋白、粗脂肪、直链淀粉质量分数等性状,并进行相关性分析。在此基础上,选取4个高容重、高淀粉质量分数、低粗蛋白质量分数、低脂肪质量分数的玉米种质籽粒和4个低容重、低淀粉质量分数、高粗蛋白质量分数、高脂肪质量分数的玉米种质籽粒进行转录组测序(RNA-Seq)分析。【结果】容重与总淀粉质量分数呈显著正相关(P<0.01),而容重与粗蛋白和粗脂肪质量分数呈显著负相关(P<0.01)。对极端种质进行RNA-Seq分析,共筛选获得159个差异表达基因,这些基因主要参与碳代谢、光合组织中的碳固定、氨基酸生物合成等过程。进一步实时荧光定量PCR对其中与碳代谢或氨基酸生物合成相关的8个候选基因表达量进行验证,发现这些基因在不同种质中的表达变化规律与容重差异变化趋势一致。【结论】阐明了玉米籽粒容重与其他品质性状之间的相关性,为高品质玉米新品种选育提供特异性种质及8个在碳还原、胚乳发育、淀粉代谢、细胞代谢和种子脂肪积累中起着重要作用的候选基因。

[Objective]As an important factor of quality traits in national maize standard regional tests,test weight is a complex quantitative trait,and its influencing factor and regulatory mechanism is still unclear.Quality traits such as starch,protein,and fat content are important factors affecting test weight,but the relationship between them is still unclear.[Method]This research determined the test weight,starch,crude protein,gross fat,and amylose content of 517 maize germplasms mainly composed of local maize germplasm resources in Zhejiang Province.On the basis of correlation analysis,the kernels of four germplasms with higher test weight,higher starch content,lower protein content,lower fat content,and four germplasms with opposite phenotypes were selected for RNA-Seq analysis.[Result]By correlation analysis,this research found there was a significant positive correlation between test weight and starch content,while a negative correlation was found between test weight and protein or fat content.RNA-Seq analysis was performed for the extreme germplasm,a total of 159 differentially expressed genes were screened between 2 groups,and 8 candidate genes related to carbon metabolism or amino acid biosynthesis were used for further analysis.The expression difference of these genes was consistent with the change of test weight in different inbred lines by RT-qPCR.[Conclusion]The correlation between test weight and other quality traits was preliminarily clarified,providing superior germplasms and 8 candidate genes that play important roles in carbon reduction,endosperm development,starch metabolism,cellular metabolism,and seed fat accumulation for the selection of new high-quality maize cultivars.