Identification And Expression Analysis Of CsTALE Family Genes In Sweet Orange(Citrus Sinensis)

Three-amino-acid-loop-extension(TALE),one of the most important transcription factor family in plants,play important roles in regulating growth and development,stress response.Sweet orange(Citrus sinensis)is one of the most important fruit worldwide.However,there are few studies on the TALE gene family in citrus.In this study,we identified and analyzed the expression of 18 CsTALE gene family members.The findings of this study could lay the foundations for elucidating the biological functions of the TALE family genes in sweet orange.The main results are as follows:1.18 CsTALE genes were identified from the sweet orange genome.The TALE gene family was classified into two subfamilies(KNOX and BEL)through phylogenetic analysis f rom Arabidopsis,poplar and rice.2.Chromosomal distribution analysis showed that the 18 CsTALE genes were distributed in all chromosomes except chromosome 9.In addition,1 tandem duplication event was identified on chromosome 3(CsTALE4 and CsTALE5).With further collinearity analyses,10 segmental duplication events were occurred in CsTALE genes.CsTALE3/9/11 were found to be involved in three duplication events.15 colinear gene pairs were identified with the model plant A.thaliana.3.Both two subfamilies of CsTALE contain a Homeobox＿KN domain.The POX domain only appears in BEL subfamily,and the KONX1 and KONX2 domains appear in the KONX subfamily.In addition,we also analyzed the gene structure and conserved motifs.The cis-element analysis of the gene promoter shows that the CsTALE gene has potential functions in sweet orange development,biological or abiotic stress.4.In order to analyze the tissue-specific analysis of CsTALE,q RT-PCR was performed o n various tissues(stems,leaves,flowers and fruits).Except for CsTALE12/14 showed low expression across all tissues,other CsTALE genes were expressed in all plant tissues to varying degrees.This suggests that CsTALE gene family showed functional diversity in regulating sweet orange growth and development.5.CsTALE genes showed different expression patterns in different biotic and abiotic stresses.Under abiotic stress treatments(high and low temperature,salt,and wounding),10 CsTALE genes were found to be responsive to high temperature,four to low temperature,eight to salt,and four to wounding.After infection with the fungal pathogen Diaporthe citri a nd bacterial pathogen Candidatus Liberibacter asiaticus,8 CsTALE genes were observed to b e significantly up-regulated,5 CsTALE genes was markedly inhibited.CsTALE genes in CLas-infected sweet orange revealed that most of these genes were up-regulated,whereas the expression of CsTALE15/17 appeared to be strongly suppressed6.We performed subcellular localization analysis of CsTALE family proteins,and the results showed that CsTALE3/10 were all localized in the nucleus.7.The transcriptional activation activity of the CsTALE protein was determined in yeast,and only CsTALE14 protein has transcript activation ability.We further verified the interaction between CsTALE3/CsTALE8,CsTALE3/CsTALE11,CsTALE10/CsTALE12,CsTALE14/CsTALE8,CsTALE14/CsTALE11 using a yeast two-hybrid system.