Genome-wide Identification Of MeERFs In Manihot Esculenta

Cassava(Manihot esculenta Crantz)is an important food crop in the tropics,and it is also a prospective energy crop.Cassava bacterial blight is one of the most important biological constraints for cassava production.Therefore,it is important to excavate related resistance genes to increase cassava yield.Ethylene response factor(ERF)plays an important role in plant growth and development,hormone signal transduction,biotic and abiotic stress response.The genomic scanning and analysis of cassava ERF transcription factors may provide a new theoretical basis for us to analyze the interaction between cassava and bacterial blight pathogen caused by Xanthomonas axonopodis pv.manihotis.Based on cassava genomic data,the whole genome scanning and predicted interaction gene of cassava ERF family were carried out by bioinformatics analysis,expression profile analysis and dual-luciferase reporter assay.The main results are as follows:1.Based on the genomic data of cassava and the results of model plant studies,the whole genome of cassava ERF transcription factors was scanned.151 MeERFs were identified in the cassava genomic sequence and distributed unevenly on 18 chromosomes of cassava.The number of MeERF genes on each chromosome ranged from 3 to 14,and the number of encoded amino acids ranged from 117 to 474 aa.The isoelectric point ranged from 4.51 to 9.3,and the molecular weight ranged from 15232.06 to 52704.53 Da.According to the study of the family of ERF transcription factors in Arabidopsis thaliana,MeERFs are divided into 10 subfamilies from I-X.All the members of the family have a highly conserved DNA binding domain,called ERF domain,at the N-terminal of the protein.2.The results of expression pattern analysis showed that 35 MeERFs had high expression level in root and leaf of KU50,Arg7,W14,respectively(FPKM value>10).26 MeERFs could be strongly induced by pathogenic strains Xamll.Take MeERF08 as an example,its FPKM value was 24.32 at the zero day after infection by pathogenic strain Xam7,however,its FPKM value reached 233.28 after seven days,.3.In order to elucidate the molecular mechanism of ERF in response to stress,based on the binding characteristics of ERF and GCC cis-element,we scanned cassava genome and found 204 genes with GCC cis-element located in their promotor region.These 204 genes were named after BF1 to BF204.The coexpression networks of 204 BFs and4.MeERFs were constructed by weighted gene coexpression network(WGCNA).The nine MeERFs with the highest correlation with nine BFs were selected for coexpression analysis.Real-time quantitative PCR was used to verify the changes of gene expression patterns of 9 MeERFs and 9 BFs in cassava leaves treated with three hormones and Xamll,the results showed that MeERF08,MeERF33,MeERF56,MeERF113,MeERF138 and BF4,BF5,BF10,BF12 can be induced by hormones and pathogen infection.These results are in consistent with the results of expression profile analysis.5.Dual-Luciferase(?)reporter assay system was used to detect the regulation of MeERFs to BFs.The results showed that MeERF08,MeERF56,MeERF104 positively regulated the promoters of BF3;MeERF133 negatively regulated the the promoters of BF3.MeERF33 and MeERF56 positively regulated the promoters of BF12,MeERF33 and MeERF104 negatively regulated the promoters of BF12.In order to study the function of ERF in cassava disease resistance,we identified the disease-related ERF and their interaction proteins from genomic level.Our results would provid a theoretical basis for further study the function of ERF in cassava disease resistance.