不同生育时期苜蓿叶片的代谢组学分析

Metabolomics Analysis of Medicago sativa L. Leaves at Different Growth Stages

以紫花苜蓿为研究对象,采用非靶向代谢组学方法,利用液相色谱电离串联质谱(LC-ESI-MS)分析不同生育时期苜蓿叶片中代谢物的变化。采用XCMS程序处理原始数据,然后应用软件SIMCA-P 14.1进行模式识别。通过正交偏最小二乘法判别分析(OPLS-DA)方法与单变量统计分析,以OPLS-DA模型VIP>1且T检验P值<0.05为筛选标准,筛选显著性差异代谢物。结果发现共27个代谢物发生显著变化,11种表达下调,16种表达上调。其中,L-谷氨酸、嘌呤、嘧啶等与粗蛋白质含量相关的代谢产物在现蕾期到中花期主要表现为下调,L-苯丙氨酸及糖类等与木质素和半纤维素合成相关的代谢产物主要表现为上调,共同导致粗蛋白质含量降低,中性洗涤纤维、酸性洗涤纤维含量增加,苜蓿的营养品质及相对饲喂价值下降。此外,乳酸及一些可溶性碳水化合物含量在中花期相对于现蕾期表现为上调,因此,中花期收获的苜蓿更宜青贮,而现蕾期收获的苜蓿粗蛋白质含量较高,更宜调制干草。

Taking alfalfa as the research object,LC-ESI-MS（Liquid chromatography tandem mass spectrometry）was used to analyze the changes of metabolites in alfalfa leaves at different growth stages.The original data was processed using the XCMS program and then pattern analysis was performed using software SIMCA-P.By means of OPLS-DA（Orthogonal partial least squares discriminate analysis）method and univariate statistical analysis,the metabolites of significant differences were screened with OPLSDA model of VIP 〉1 and P value 〈0.05 as screening criteria,of which a total of 27 metabolites were significantly changed,11 metabolites express were down-regulated and 16 metabolites express were upregulated.The contents of L-glutamic acid,purine,pyrimidine and other crude protein related metabolites were mainly down-regulated during the budding stage to the mid flowering stage,L-phenylalanine and carbohydrates associated with lignin and hemicellulose synthesis were mainly expressed as up-regulated.During the development of alfalfa,the change of these substances may be an important factor leading to the decrease of alfalfa CP content,the increase of NDF and ADF content and decrease of the nutritional quality and the RFV of alfalfa.In addition,lactic acid and some soluble carbohydrate in the flowering period relative to the budding period showed up-regulated,therefore,the alfalfa harvested in the mid flowering stage was more suitable for silage,while the alfalfa crude protein content was higher in the budding stage,and the hay was better