基于转录组学和代谢组学解析氮调控花生结瘤固氮的机理

Mechanism Analysis of Nitrogen Regulation on Peanut Nodulating Based on Transcriptomes and Metabonomics

花生是一种重要的豆科作物,能与根瘤菌共生固氮,但该过程受到土壤中氮素的严格调控,施氮量过高时会形成“氮阻遏”效应。目前关于氮素调控花生结瘤固氮机理的研究较少。本研究以花育22号为试验材料,设置90 kg/hm^(2)氮处理和对照(不施氮),统计根瘤数、测定固氮酶活性并进行转录组学、代谢组学及双组学联合分析。结果表明,施氮处理显著减少根瘤数,降低根瘤固氮酶活性。经转录组分析,共鉴定出3123个差异表达基因,富集在生物过程、细胞组成和分子功能三大类;从中筛选出13个与氮调控花生结瘤固氮有关的基因,分别编码生长素应答蛋白和响应因子、鸟氨酸脱羧酶、天冬酰胺合成酶、谷氨酰胺合成酶、谷氨酸合酶、苹果酸脱氢酶、苹果酸酶等。经液相色谱串联质谱法分析,共鉴定到201种差异代谢物,包括酚酸、黄酮、氨基酸等共12大类物质,其中黄酮类代谢物占比最高,约占19.9%。通过对转录组学和代谢组学的联合分析发现,氮素主要通过植物激素信号转导、次生代谢物生物合成、氮代谢等途径调控花生结瘤固氮。本研究结果可为深入研究氮素调控花生结瘤固氮的分子机理提供信息基础。

Peanut,as an important leguminous crop,can fixing nitrogen with symbiotic rhizobia.Howev-er,this process is strictly regulated by soil nitrogen,and excessive nitrogen application will result in“Nitrogen Repression”.At present,there are fewer studies on the mechanism of nitrogen regulating peanut nodulating and nitrogen fixation.In this study,Huayu 22 was used as experimental material to calculate root nodules,determine nitrogenase activity,and conduct the transcriptomic,metabonomics and dual omics analyses after treated with 90 kg/hm^(2)nitrogen(N)and no nitrogen(CK).The results showed that N treatment significantly reduced the root nodule number and nitrogenase activity.By RNA-Seq analysis,a total of 3123 differentially expressed genes were identified,which were annotated in biological processes,cellular components and molecular functions.Thirteen genes related to nitrogen regulating peanut nodulating and nitrogen fixation were selected,which encoded auxin response protein factors,ornithine decarboxylase,asparagine synthetase,glutamate synthase,malic dehydrogenase,malic enzyme,etc.A total of 201 different metabolites were identified by liquid chromatography-tandem mass spectrometry,including 12 categories such as phenolic acids,flavonoids and a-mino acids;among them,flavonoids accounted for the highest proportion as about 19.9%.Through the com-bined analysis of transcriptomics and metabolomics,it was found that nitrogen regulated peanut nodulating and nitrogen fixation mainly through plant hormone signal transduction,biosynthesis of secondary metabolites,nitrogen metabolism and other pathways.These results could provide information bases for further research on the molecular mechanisms of peanut nodulating and nitrogen fixation regulated by nitrogen.