谷子籽粒类黄酮含量和粒色的QTL定位

QTL mapping for flavonoid content and seed color in foxtail millet

谷子(Setaria italica L.)是我国北方地区重要的粮食作物,籽粒营养丰富,且富含多种类黄酮物质,对生长发育和品质形成发挥着重要作用。目前谷子籽粒类黄酮合成及粒色形成相关调控机制研究较少。分析谷子类黄酮含量及粒色性状相关的QTL,为类黄酮合成关键基因的精细定位、克隆及功能研究奠定基础,同时,也为揭示谷子类黄酮合成及代谢机制和培育富含类黄酮谷子品种提供技术支撑。本研究以红粒色高类黄酮品种金苗红酒谷和黄粒色低类黄酮品种豫谷28为亲本构建的包含150个家系的重组自交系(RIL)群体为试验材料,在谷子成熟期对籽粒粒色和类黄酮含量相关性状进行分析。同时,采用复合区间作图法(composite interval mapping,CIM)对粒色和类黄酮含量进行QTL定位与分析,并对QTL置信区间内的候选基因进行预测。相关性分析表明,类黄酮含量与粒色呈显著正相关。共定位到4个与类黄酮含量相关和11个与粒色相关的QTL,分别位于1号、2号、5号、6号、7号、8号和9号染色体上,单个QTL的表型贡献率为2.01%~29.25%,6个为主效QTL,其中,qSC1-2和qFLA1-1、qSC7-1和qFLA7-1、qSC9-3和qFLA9-1为2个性状下共同定位到的QTL。通过基因预测与功能注释,筛选出QTL置信区间内5个与类黄酮物质合成及代谢相关的候选基因,表明类黄酮物质的合成、代谢及利用相关基因极有可能控制了这些基因的表达。15个QTL分别聚集于7条染色体上,基于基因功能注释,共筛选了5个与谷子类黄酮合成及代谢相关的候选基因,表明不同QTL位点参与到了共同遗传机制,并可通过分子标记辅助选择进行类黄酮合成及代谢等有利基因的聚合育种。

Foxtail millet(Setaria italica L.)is an important grain crop in northern China.The grain is rich in nutrients and many kinds of flavonoid,which plays an important role in growth and quality formation.At present,there are few studies on the regulatory mechanisms of flavonoid synthesis and seed color formation in foxtail millet.The quantitative trait loci(QTL)analysis of flavonoid content and seed color traits in foxtail millet laid a foundation for fine mapping,cloning,and functional study of key genes for flavonoid synthesis,and it also provided technical support for revealing the mechanism of flavonoid synthesis and metabolism in foxtail millet and cultivating millet varieties rich in flavonoid.In this study,a recombinant inbred line(RIL)population consisting of 150 families was used as the experimental materials,which was constructed using a red seed-color high-flavonoid variety Jinmiaohongjiugu and a yellow seed-color low-flavonoid variety Yugu 28 as the parents.The related traits of seed color and flavonoid content were analyzed at maturity stage in foxtail millet.At the same time,composite interval mapping(CIM)was used to locate and analyze QTL for seed color and flavonoid content,and the candidate genes within the QTL confidence intervals were predicted.Correlation analysis showed that flavonoid content was significantly positively correlated with seed color.A total four and eleven QTL associated with flavonoids content and seed color were located on chromosomes 1,2,5,6,7,8,and 9,respectively,and individual QTL phenotypic contribution rate was 2.01%–29.25%,six major QTLs were identified,qSC1-2 and qFLA1-1,qSC7-1 and qFLA7-1,qSC9-3,and qFLA9-1 were co-localized QTL under both two traits.Through gene prediction and functional annotation,five candidate genes related to flavonoid synthesis and metabolism in the confidence interval of QTL were screened,indicating that the genes related to flavonoid synthesis,metabolism,and utilization were most probably to regulate the expression of these genes.15 QTL were clustered on seven chromosomes,respectively,and five candidate genes related to flavonoid synthesis and metabolism were screened based on gene functional annotation,indicating that different QTL loci were involved in the common genetic mechanism,and the pyramiding breeding of beneficial genes such as flavonoid synthesis and metabolism could be carried out through molecular marker-assisted selection.