| Wheat is one of the major food crops in the world.With the growth of world population and global climate change and other factors,how to ensure food security has gradually become an urgent challenge to be solved.External signals,including abiotic stresses caused by light,temperature and other conditions,can greatly affect plant growth and development,and CAMTA is a key transcription factor in the Ca2+signal transduction pathway,which not only affects the process of plant growth and development,but also participates in the regulation of drought,salt,cold and heat stresses.In this study,we integrated bioinformatics and molecular biology approaches to screen and identify the CAMTA transcription factor family in wheat,and analyzed the physicochemical properties,gene structure,evolutionary relationships,conserved protein motifs,and cis-acting elements of the family members.The expression patterns of this family of genes were analysed by q PCR for tissue specificity and a variety of stress treatments,and it was found that TaCAMTAs were expressed in all tissues and responded to different kinds of stress treatments,with particularly significant results for drought stress.In order to investigate the relationship between the CAMTA family and drought,the main candidate gene TaCAMTA1b-B.1 was screened and cloned from wheat and a preliminary functional study was carried out.The overexpression of TaCAMTA1b-B.1 in transgenic wheat enhanced drought tolerance while the drought tolerance of gene silenced plants decreased,indicating that TaCAMTA1b-B.1 is a positively regulated gene in drought stress.This study not only provides an important genetic resource for the selection and breeding of drought-resistant wheat,but also has important reference value for the study of crop stress resistance.The main findings are as follows:1.Combined with the database,a total of 17 CAMTA family genes were identified in common wheat,and the encoded protein was in the range of 138～1066amino acids.The molecular weight was 16.31～119.32 k Da,furthermore,the isoelectric point was between 5.32 and 9.57,and the number of introns were between4～14.Phylogenetic analysis founded that the TaCAMTA family could be divided into three subfamilies,distributing on 10 chromosomes of 17 wheat chromosomes.2.The tissue-specific expression patterns of wheat CAMTA family genes were analyzed using public RNA-seq data combined with RT-q PCR,and the results showed that wheat CAMTA family genes were expressed in roots,stems,leaves,spikes and seeds,with seedlings mainly expressed in the above ground and reproductive stages mainly expressed in leaves.3.The expression patterns of wheat CAMTA family genes under abiotic stress and hormone ABA stress were analyzed,and it was found that the family members generally responded to drought,high salt and low temperature stresses,among which mainly responded to drought stress.4.The important drought stress gene TaCAMTA1b-B.1 was screened and cloned.The wheat plants with overexpression（OE）and silent expression（RNAi）of TaCAMTA1b-B.1 were obtained using Agrobacterium-mediated genetic transformation.Phenotypic statistics of OE,RNAi and wild-type（WT）plants under drought stress conditions showed that there were no significant differences in phenotypic changes of RNAi plants compared with WT plants,but the survival rate of OE plants was significantly higher and the water loss rate of leaves was reduced.The MDA content was increased under drought treatment.Analysis of the phenotypic results indicated that overexpression of TaCAMTA1b-B.1 gene caused wheat to exhibit greater tolerance to drought stress.5.This study found two new members of CAMAT family,TaCAMTA5-B.1 and TaCAMTA5-B.2.The results of yeast two hybrid experiment showed that both TaCAMTA5-B.1 and TaCAMTA5-B.2 proteins had no self-activating reporter gene activity,and TaCAMTA5-B.1 could interact with Ta Ca M protein,indicating that TaCAMTA5-B.1 may possess the molecular function of CAMAT family. |
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