| Pectin methyl esterase(PME)belongs to the carbohydrate esterase family CE-8,the main role is to adjust the degree of pectin methyl esterification,and pectin is the main component of plant cell wall.Because the cell wall constitutes a physical barrier between the external environment and the internal material of the plant cell,the modification of the pectin in the cell wall is usually associated with plant defense responses.The development and application of Arabidopsis microarray database revealed that most PME gene expression levels varied with changes in biological and abiotic stress.Pectin methyl esterase is involved in plant vegetative growth and reproductive growth processes such as cell wall expansion and enhancement,cell separation,seed germination,root tip elongation,leaf growth polarity,internode stem growth,wood formation,pollen formation and pollen Tube growth,dry fruit cracking and fruit ripening softening.In order to further study the function of tomato PME gene family,the bioinformatics method was used to identify the members of PME gene family in tomato genome,and the genomic information,protein physiological and biochemical characteristics,gene structure,conserved domain and phylogenetic tree were studied.The results were as follows: 79 PME genes and 23 PMEI genes were identified in the tomato genome,which could be divided into two groups: PME Group Ⅰ,PME Group Ⅱ and PMEI Group Ⅲ.Group Ⅰ could be further divided into two branches.The results showed that there were 20 tandem repeats,including 49 genes.Tandem repeats were the main way of tomato PME gene amplification,and there were obvious tandem repeats.The analysis of PME gene structure showed that the PME gene was conserved in the evolution process.After comparing the amino acid sequence of tomato PME protein,five typical conserved structures were found.The MEME software was used to analyze the tomato PME Protein conserved motifs were analyzed to find eight more conserved motifs.Then,according to the transcriptome data of the known tomato fruit,ten PME genes(three genes that are tandem repeats)whose expression levels were consistently high before the fruit coloring stage were selected.After studying the ethylene treatment,the expression of these genes Solyc03g12760,Solyc07g09170,Solyc06g009190 and Solyc12g098340 are negative regulatory genes.The results showed that Pecu1,Solyc03g083360,Solyc07g017600 and Solyc07g064190 were positive regulatory genes in response to ethylene signal.Solyc03g123620,Solyc00g027770,Solyc06g009190 and Solyc12g098340 were negative regulatory genes.The results showed that the leaves of the two plants were treated with wild type(WT)and antisense Pmeu1 tomato plants(PE1as)as the research materials.After the infection of Botrytis cinerea,On the formation of the lesion area was significantly smaller than the antisense expression of plants.At the same time,the amount of ethylene released from the leaves after inoculation was measured.After the inoculation,the ethylene release was significantly increased,both in wild and antisense.Previous analysis of microarray data showed that the expression of Pmeu1 gene in tomato fruit was significantly increased after infection or stinging of Botrytis cinerea.Finally,the esterification degree of pectin in leaves of two types of plants was analyzed.It was found that the esterification degreeof pectin in leaves of wild type plants was significantly lower than that of antisense plants.In this study,we propose a possible mechanism of pectin methylesterase gene resistance to Botrytis cinerea,and the increase of ethylene release during the process of Botrytis cinerea infecting plants increases the Pmeu1 expression of pectin methyl esterase gene up-regulated,produce resistance. |
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