Résumé
As one kind of v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factors, R1-MYB (MYB-related) family plays an important role in plant growth and development, as well as environmental stress and hormone signal transduction. In this study, R1-MYB family genes in Rheum palmatum L. were systematically screened based on full-length transcriptome sequencing analysis. Firstly, the physicochemical, protein domain and molecular evolution characteristics of the coding proteins were analyzed. Furthermore, the tissue expression levels of R1-MYB genes were analyzed by RNA-seq. We also investigated the expression pattern of RpMYB24 in response to various hormones and abiotic stresses. The results showed that a total of 49 R1-MYB genes were identified, which mainly encoded thermally stable hydrophilic proteins. Most of the deduced proteins were predicted to locate in nucleus. Each protein had a large proportion of random curl and α helix, and also had the W-type conserved amino acids which were the signature of MYB. R1-MYB family members were distributed in five subgroups, including circadian clock associated 1 (CCA1)-like, I-box (GATAAG)-like, CAPRICE (CPC)-like, telomere repeat binding factor (TRF)-like and TATA binding protein (TBP)-like, and the number of CCA1-like was the majority. RNA-seq revealed that 49 R1-MYB genes were differentially expressed in roots, rhizomes and leaves of R. palmatum, and the expression levels of 15 and 23 genes in roots and rhizomes were higher than those in leaves, respectively. RpMYB24 transcript was induced by abscisic acid (ABA), salicylic acid (SA), and methyl jasmonate (MeJA) treatment, and could also significantly respond to injury, low temperature and high temperature stresses except drought stress. This study systematically identified the R1-MYB family genes and their molecular characteristics, better for further gene functional validation, and then provide a scientific basis for the transcriptional regulation mechanism research into rhubarb quality formation.
Résumé
Objective To clone the R1-MYB transcription factor participated in the anthocyanidin metabolism, and to analyze by bioinformatics analysis. Different expression of different varieties, different organs of the same species and salt stress conditions in Lycium were analyzed. To clone the full-length cDNA encoding R1-MYB, to perform bioinformatic analysis, and to study its expression in different cultivators and different developmental stage and in response to NaCl stress in Lycium ruthenicum and L. barbarum. Methods The full-length cDNA encoding R1-MYB was cloned using homology-based cloning and rapid amplification of cDNA ends (RACE) technique in L. ruthenicum, and the homologous gene was obtained by transcriptome in L. barbarum. The bioinformatics analysis was carried out by using Prot, Param, Smart, PSORT, and SOPMA methods. And the phylogenetic tree was constructed based on software MEGA5.0. Gene expression analysis was done by method of Real-time PCR. Results We the MYB transcription factor in L. ruthenicum was cloned and named as LrMYB1R1 (GenBank accession number KY568981), and LbMYB1R1 (GenBank accession number KY568982) in L. barbarum. Bioinformatics analysis showed that the length of LrMYB1R1 was 1 496 bp and the CDS was 927 bp. The coding products contained 308 amino acids, the molecular weight of the protein was 33 400 and 33 490, the theoretical isoelectric point was 7.80 and 7.78, belonging to the R1-MYB transcription factor, and the encoded protein is predicted to be located in the nucleus. The results of phylogenetic tree analysis showed that LrMYB1R1 and LbMYB1R1 were highly similar to MYB1R1-like protein in Solanum lycopersicum, Solanum tuberosum, and Nicotiana tabacum. Real-time PCR analysis showed that LrMYB1R1 had higher expression level in leaves and young fruits in L. ruthenicum, followed by stems, young leaves, flowers, purple fruits and black fruits, only slightly expressed in roots. In addition, the relative expression levels of LrMYB1R1 decreased in response to salt stress. Conclusion The study of R1 MYB transcription factor has been enriched, which has laid the foundation for the subsequent research on gene function and for the high-yielding anthocyanin by genetic engineering method in L. ruthenicum.