Research On Gene Regulation Mechanism Of Low Temperature Stress In Alfalfa

Winter damage,especially in northern climates,is a major limitation of the utilization of perennial forages such as alfalfa.Therefore,improving freezing tolerance is imperative in alfalfa genetic breeding.However,freezing tolerance is a complex trait that is determined by many genes.To understand the complex regulation mechanisms of freezing tolerance in alfalfa,we performed physiological and biochemica analysis,transcriptome sequencing analysis,and constructed weighted gene co-expression network.The main results are as follows:1.Response of main physiological indexes of cold resistance to low temperature in different varieties of alfalfaUnder the cold stress,the study of different varieties of alfalfa leaf and the regularity of changes of physiological indexes,The results showed that under the cold stress,the POD and CAT content were higher than the control group,the content of CHL was lower than that of control group,and the value of EC was higher than that of control group,which was consistent with the results previously reported.Analysis of variance showed that the content of EC was highly significant difference(P<0.01).It was suggested that the cold stress of alfalfa could be measured by EC indexes.2.Transcriptome sequencing analysis of alfalfa in cold stressTranscriptome sequencing analysis of alfalfa response to freezing stress was performed,and 80,005 transcripts have been identified based on high-throughput sequences,and 61,444 Unigene were annotated.These genes annotation results were associated with response to stress,lipid metabolism,signal transduction,ribosomal structure and biogenesis,and so on.In addition,further analysis revealed that MYB,AP2/ERF,WRKY,and other gene families may play a key regulatory role in cold resistance of medicago sativa.Finally,a strong correlation between EC and FT was found through the analysis of gene expression differences between FT and four physiological and biochemical indexes,indicating that membrane permeability can significantly reflect the cold resistance of alfalfa under low temperature stress.3.Analysis of co-expression network of cold stress weighted genes in alfalfaUsing the weighted gene co-expression network analysis(WGCNA)from 18 samples identified 41 alfalfa cold stress module,study its and alfalfa under cold stress relationship between physiological and biochemical characters,select the key modules in the process of alfalfa cold coral2 construct gene regulatory networks,at the same time,within the module coral2 on analyzing function of enrichment of expressed genes.It was found that alfalfa may participate in response to cold stress through ribosomal structure and biogenesis.