Genome-wide identification of the MYB transcription factor family in kiwifruit and analysis of its expression pattern in response to salt stress

Abstract

As the king of vitamin C, kiwifruit has high nutritional and economic value. However, with the expansion of its planting area and the application of a large amount of farm manure represented by large livestock manure, kiwifruit is at increasing risk of salt stress, so it is urgent to select salt-tolerant strains of kiwifruit. MYB transcription factors (TFs) play a vital role in responding to abiotic stress and regulating the synthesis of secondary metabolites. There are relatively few reports on the specific gene functions of MYB TFs. In this study, based on the kiwifruit genome database and transcriptome sequencing data, we used bioinformatics to analyze the structure, evolution, and expression patterns of kiwifruit MYB TFs. The results showed that 226 AcMYB TFs were identified, and the phylogenetic analysis classified them into 32 subfamilies. Analysis of the gene structure and conserved motifs revealed that the exon and intron structures of AcMYB in the same subfamily are relatively identical, with only minor differences. In addition, we predicted cis-acting elements associated with hormones, light responses, etc., at the 2000 bp upstream position of the promoter of the AcMYB TFs. Expression profiling based on transcriptome data showed a total of 24 differentially significant genes, of which 11 genes were upregulated, and 13 genes were downregulated. AcMYB100, AcMYB186, AcMYB81, and so on upregulated genes by positively regulating salt stress to minimize the effects caused to the plants, AcMYB145, AcMYB88, AcMYB1, and so on downregulated genes reduced the salt stress effects on plants by negatively regulating salt stress. It suggests that these MYB TFs can modify the effects of salt on kiwifruit. We also identified the signaling pathway of stress regulating MYB TFs in response to salt stress in kiwifruit plants. These results provide a basis for understanding the biological functions and characteristics of the MYB TF family and lay a foundation for further research on salt tolerance breeding in kiwifruit.