Analysis Of The Mechanism Of Alfalfa Nutrition Quality Change Based On Proteomics And Metabonomics

In this study,alfalfa was used as the experimental material to analyze the nutrient composition of leaves at different growth stages.At the same time,proteomics and metabolomics techniques were used to analyze the differences in the expression of proteins and metabolites in alfalfa leaves of different growth stages.The purpose of this study is to use proteomics and metabolomics techniques to study the underlying causes of changes in nutrients from the molecular level and explore the rational use patterns of alfalfa in different growth stages.It lays a certain theoretical foundation for alfalfa timely harvesting,reasonable and efficient utilizing,and provides new directions and ideas for future research.Through the study,the following conclusions were obtained:(1)Proteomics identified 415 differential proteins at the flowering-budding stage(Fold change > 1.2,P < 0.05),of which 159 were up-regulated and 256 were down-regulated.In the process of growth from the budding to mid-flowering stage,the protein in the cell,cell membrane,and organelles,which has catalytic and binding functions,undergoes changes in metabolic processes,cellular processes,and stimulus response.(2)A total of 49 metabolites(VIP > 1,P < 0.05)were identified by non-targeted metabolomics.Among them,24 metabolites were significantly up-regulated at mid-flowering stage and 25 were significantly down.Differential metabolites mainly include amino acids,organic acids,carbohydrates,purines,lipids,pyrimidines,flavonoids.L-glutamic acid,L-glutamine,L-asparagine,purine,pyrimidine and other protein synthesis related metabolites decreased significantly,while the expression level of L-phenylalanine,carbohydrates and lipids were significantly up-regulated.(3)Through the joint analysis of proteome and metabolomics data,it was found that with the prolonged growth stage of alfalfa,The contents of L-glutamic acid,L-glutamine,L-asparagine,guanine,adenine,uracil and dihydrourine pyrimidines were reduced,and some of the proteins were hydrolyzed,resulting in a decrease in the crude CP content in mid-flowering alfalfa;?-glucosidase,?-amylase,UDP-glucuronide decarboxylase,and D-mannose are up-regulated during mid-flowering,and they both provide a raw material for the synthesis of the hemicellulose,resulting in an increase in the NDF content;Cinnamyl-alcohol dehydrogenase(CAD)and L-phenylalanine were up-regulated at mid-flowering stage,which promoted the synthesis of lignin and resulted in increasedNDF and ADF content.Taken together,the above results have led to a continuous decline in the RFV of alfalfa from budding to mid-flowering stage.(4)Alfalfa harvested at the budding stage to the early flowering stage have high CP content,lower NDF and ADF content,and higher RFV,which is more suitable for making hay.The high content of carbohydrates in the early flowering stage to mid-flowering stage of alfalfa is conducive to the improvement of the silage quality and are more suitable for the production of silage.