转录组和代谢组分析钙调控花生结瘤固氮的机理

The Mechanisms of Calcium Regulation on Peanut Nodulation and Nitrogen Fixation Analyzed by Transcriptomes and Metabonomics

作为一种重要的豆科作物,花生能与根瘤菌共生固氮,该过程受到钙元素的调控。目前,关于钙调控花生结瘤固氮的机理少有报道。本研究以花育22号为试验材料,对CaO处理组和对照组的花生根系进行转录组、代谢组以及双组学联合分析。转录组分析共鉴定出2313个差异表达基因,主要富集在代谢途径,包括精氨酸和脯氨酸代谢等。基于液相色谱串联质谱法进行的代谢组分析共鉴定出48种差异代谢物,包括黄酮、氨基酸、酚酸等12大类物质。研究表明,CaO处理使花生根系的精氨酸和组氨酸含量增加,对根瘤菌的趋化作用增强,有利于根瘤菌侵染,进而促进结瘤。花生根瘤中编码谷氨酸合成酶/谷氨酰胺合成酶的基因上调,有利于NH_(3)被同化为谷氨酰胺,这可能与钙促进根瘤固氮有一定相关性;根瘤中编码蔗糖合酶和苹果酸脱氢酶的基因上调,固氮所需的能量增加可能是钙促进根瘤固氮的另一原因。本研究结果将为深入研究钙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 symbiotically fix nitrogen with rhizobia,which is regulated by calcium element.At present,there are few reports on the mechanism of calcium regulating peanut nodulation and nitrogen fixation.In this study,Huayu22 was used as experimental material to analyze the transcriptome,metabolome and dual omics of peanut roots treated with calcium and control group.A total of 2,313 differentially expressed genes were identified by transcriptome analysis,which was mainly enriched in metabolic pathways including arginine and proline metabolism.A total of 48 differential metabolites were identified by the metabolome analysis based on liquid chromatography-tandem mass spectrometry,including 12 categories of flavonoids,amino acids,phenolic acids and so on.The results showed that calcium treatment increased the contents of arginine and histidine in peanut roots,and enhanced the chemotaxis of rhizobia,which was conducive to the infection of rhizobia,and then affected the nodulation.The up-regulation of GS/GOGAT gene in peanut root nodules is conducive to the assimilation of NH_(3) to glutamine,which may be related to the promotion of nitrogen fixation in root nodules by calcium.The up-regulation of genes encoding sucrose synthase and malate dehydrogenase in root nodules and the increase of energy required for nitrogen fixation may be another reason explaining calcium promotes nitrogen fixation in root nodules.The results of this study will provide information basis for further study on the molecular mechanism of calcium regulation of peanut nodulation and nitrogen fixation.