Identification and expression analysis of R2R3-MYB gene family in Andrographis paniculata / 中国中药杂志

The plant growth, development, and secondary metabolism are regulated by R2 R3-MYB transcription factors. This study identified the R2 R3-MYB genes in the genome of Andrographis paniculata and analyzed the chromosomal localization, gene structure, and conserved domains, phylogenetic relationship, and promoter cis-acting elements of these R2 R3-MYB genes. Moreover, the gene expression profiles of R2 R3-MYB genes under abiotic stress and hormone treatments were generated by RNA-seq and validated by qRT-PCR. The results showed that A. paniculata contained 73 R2 R3-MYB genes on 21 chromosomes. These members belonged to 34 subfamilies, 19 of which could be classified into the known subfamilies in Arabidopsis thaliana. The 73 R2 R3-MYB members included 36 acidic proteins and 37 basic proteins, with the lengths of 148-887 aa. The domains, motifs, and gene structures of R2 R3-MYBs in A. paniculata were conserved. The promoter regions of these genes contains a variety of cis-acting elements related to the responses to environmental factors and plant hormones including light, ABA, MeJA, and drought. Based on the similarity of functions of R2 R3-MYBs in the same subfamily and the transcription profiles, ApMYB13/21/35/67/73(S22) may regulate drought stress through ABA pathway; ApMYB20(S11) and ApMYB55(S2) may play a role in the response of A. paniculata to high temperature and UV-C stress; ApMYB5(S7) and ApMYB33(S20) may affect the accumulation of andrographolide by regulating the expression of key enzymes in the MEP pathway. This study provides theoretical reference for further research on the functions of R2 R3-MYB genes in A. paniculata and breeding of A. paniculata varieties with high andrographolide content.

Identification and expression profiling of R2R3-MYB transcription factors in Erigeron breviscapus / 中国中药杂志

R2 R3-MYB transcription factors are ubiquitous in plants, playing a role in the regulation of plant growth, development, and secondary metabolism. In this paper, the R2 R3-MYB transcription factors were identified by bioinformatics analysis of the genomic data of Erigeron breviscapus, and their gene sequences, structures, physical and chemical properties were analyzed. The functions of R2 R3-MYB transcription factors were predicted by cluster analysis. Meanwhile, the expression patterns of R2 R3-MYB transcription factors in response to hormone treatments were analyzed. A total of 108 R2 R3-MYB transcription factors, named EbMYB1-EbMYB108, were identified from the genome of E. breviscapus. Most of the R2 R3-MYB genes carried 2-4 exons. The phylogenetic tree of MYBs in E. breviscapus and Arabidopsis thaliala was constructed, which classified 234 MYBs into 30 subfamilies. The MYBs in the five MYB subfamilies of A.thaliala were clustered into independent clades, and those in E. breviscapus were clustered into four clades. The transcriptome data showed that MYB genes were differentially expressed in different tissues of E. breviscapus and in response to the treatments with exogenous hormones such as ABA, SA, and GA for different time. The transcription of 13 R2 R3-MYB genes did not change significantly, and the expression patterns of some genes were up-regulated or down-regulated with the extension of hormone treatment time. This study provides a theoretical basis for revealing the mechanisms of R2 R3-MYB transcription factors in regulating the growth and development, stress(hormone) response, and active ingredient accumulation in E. breviscapus.

Cloning, subcellular localization and expression analysis of a transcription factor gene SmMYB87 in Salvia miltiorrhiza / 中草药

Objective To clone the R2R3 MYB transcription factor gene SmMYB87 in subgroup 14 from Salvia miltiorrhiza, and analyze the bioinformatics and expression of this gene. Methods Total RNA extracted from S. miltiorrhiza was used as cDNA synthesis template and the full length cDNA sequence was obtained through homology-based cloning and rapid amplification of cDNA ends (RACE) technology. The structure and physicochemical properties of SmMYB87 gene and its coded protein were analyzed with bioinformatics softwares. The expression of SmMYB87 in different organs was determined with qRT-PCR, and a GFP fusion expression vector was constructed to investigate the subcellular laicization of SmMYB87 protein. Results SmMYB87 gene contained two introns and an open reading frame (ORF) of 732 bp, encoding 243 amino acid polypeptides. It expressed in roots, stems, leaves and flowers with similar expression levels and the SmMYB87 protein located in nucleus and cytomembrane. Conclusion The analysis of sequence structure and expression pattern of SmMYB87 will be helpful to study the regulating roles of this gene in S. miltiorrhiza.