| Since the homologous gene sequence and chromatin environment produced by repetitions of the whole genome are the same,theoretically they should have the same expression level.However,after the selection pressure during the whole evolution process,they have already appeared obvious functional differences and expression differences.Therefore,from the species level,it is particularly important to clarify the expression patterns,functional differences,and the correlation between expression levels and sequence differences of paralogous genes of the model plant Arabidopsis under different selection pressures.In addition,from the gene family level,the 1A acyltransferase(SCPL1A)gene family plays an important role in the synthesis of tea catechins and has also undergone multiple genome-wide duplications,and these duplications are usually under different stress conditions.It is differentially expressed,but the phylogenetic relationship of the SCPL1 A gene family in tea plants and the regulatory mechanism under different stresses are still unclear.Therefore,clarifying the phylogenetic relationship of the SCPL1 A gene family and the construction of its interaction network with transcription factors is a key step in the study of tea polyphenol synthesis.Based on the background of genome-wide duplication,this study conducted detailed studies on the gene evolution,expression patterns,sequence differences and co-expression networks of Arabidopsis and tea plants from the species and gene family levels.The results are as follows.1.This study first identified the paralogous genes of Arabidopsis thaliana,and then analyzed the differential expression patterns of these genes under four different stresses and divided them into three types.Secondly,the expression patterns of their paralogous genes increase and decrease with increasing pressure under different stresses,and it is concluded that the expression level of paralogous genes is related to the type of stress and its severity.Then,the corresponding co-expression network of the differentially expressed paralogous genes and transcription factors was constructed,and it was concluded that the differentially expressed paralogous genes with enhanced mode were compared with the differentially expressed paralogous genes with reduced expression patterns and the transcription factor.There are more interactions between them.Third,the correlation between expression level and sequence difference is determined,and a positive correlation between expression level and sequence difference is calculated.Finally,the study found that paralogous genes that experience loose selection pressure tend to be redundant in function,while paralogous genes that experience strong positive selection pressure tend to have more sequence differences.2.In the study of tea plant SCPL1 A gene family,the phylogenetic relationship of SCPL1 A gene family in six species was analyzed,and the structure,conserved motifs and cis-acting elements of tea plant SCPL1 A gene family members were studied.Then analyzed the expression patterns of SCPL1 A gene family under two stresses,and concluded that the functions of these genes are different under different stresses.Furthermore,a co-expression network of SCPL1 A gene and transcription factor under different stresses was constructed,and it is predicted that SCPL1 A gene family is more strongly regulated by transcription factors under mechanical damage stress.Finally,the SCPL1 A gene differentially expressed under different stresses was selected for q RT-PCR analysis to verify the reliability of the data.On the one hand,these studies can reveal the differential expression patterns of paralogous genes under different stresses,and at the same time provide new insights into understanding the relationship between expression levels and sequence differences.On the other hand,it also provides a reference for further research on how the SCPL1 A gene in tea plants participates in the production of catechins,and how to improve the quality and yield of tea plants. |
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