Genome-wide analysis of MYB transcription factor family and AsMYB1R subfamily contribution to ROS homeostasis regulation in Avena sativa under PEG-induced drought stress

Abstract

Background: The myeloblastosis (MYB) transcription factor (TF) family is one of the largest and most important TF families in plants, playing an important role in a life cycle and abiotic stress.

Results: In this study, 268 Avena sativa MYB (AsMYB) TFs from Avena sativa were identified and named according to their order of location on the chromosomes, respectively. Phylogenetic analysis of the AsMYB and Arabidopsis MYB proteins were performed to determine their homology, the AsMYB1R proteins were classified into 5 subgroups, and the AsMYB2R proteins were classified into 34 subgroups. The conserved domains and gene structure were highly conserved among the subgroups. Eight differentially expressed AsMYB genes were screened in the transcriptome of transcriptional data and validated through RT-qPCR. Three genes in AsMYB2R subgroup, which are related to the shortened growth period, stomatal closure, and nutrient and water transport by PEG-induced drought stress, were investigated in more details. The AsMYB1R subgroup genes LHY and REV 1, together with GST, regulate ROS homeostasis to ensure ROS signal transduction and scavenge excess ROS to avoid oxidative damage.

Conclusion: The results of this study confirmed that the AsMYB TFs family is involved in the homeostatic regulation of ROS under drought stress. This lays the foundation for further investigating the involvement of the AsMYB TFs family in regulating A. sativa drought response mechanisms.

Keywords: Avena sativa; Drought stress; MYB transcription factors; ROS.

Fig. 1

The conserved amino acid sequences logo of AsMYB2R proteins. (A) The sequence logo of the R2 conserved domain includes three conserved tryptophan residues. (B) The sequence logo of the R3 conserved domain. The typically conserved tryptophan amino acid sites were labeled by black *, and red * represents the substituted amino acid site in the R3 domain. (C) The detail information of AsMYB1R TFs conserved motifs includes E-value, site and width. (D) The detail information of AsMYB2R TFs conserved motifs includes E-value, site and width

Fig. 2

Distribution of AsMYB TFs on A. sativa chromosomes. The chromosomal position of each AsMYB TFs was mapped to the A. sativa genome. ChrUn represents genes that have failed to assemble onto the chromosomes

Fig. 3

The phylogenetic tree plots of AtMYB and AsMYB TFs. (A) The phylogenetic tree plot of AsMYB1R and AtMYB1R TFs. The AsMYB1R TFs are divided into 5 subgroups (CCK1-like, CPC-like, TBP-like, I-box-binding-like, and R-R). (B) The phylogenetic tree plot of AsMYB2R and AtMYB2R TFs. The AsMYB2R TFs are divided into 34 subgroups (S1-S34). Yellow and green dots represent AtMYB TFs and AsMYB TFs, respectively

Fig. 4

Conserved motif, gene structure, and phylogenetic tree plots of AsMYB TFs. (A) The plot of AsMYB1R TFs; (B) The plot of AsMYB2R TFs. Conserved motifs are highlighted with different colored backgrounds and numbers, and their position in each MYB sequence was determined. The CDS, UTR and Myb DNA-binding site were mapped on the genes and indicated by different colors, respectively

Fig. 5

Gene duplication plots of AsMYB1R TFs. The gray line represents all duplication events in A. sativa genome, the yellow line represents the AsMYB1R TFs duplication events, and the heat map represents the gene density in A. sativa genome

Fig. 6

Gene duplication plots of AsMYB2R TFs. The gray line represents all duplication events in A. sativa genome, the red line represents the AsMYB2R TFs duplication events, and the heat map represents the gene density in A. sativa genome

Fig. 7

Gene duplication plots of AsMYB3R TFs. The gray line represents all duplication events in A. sativa genome, the blue line represents the AsMYB3R TFs duplication events, and the heat map represents the gene density in A. sativa genome

Fig. 8

Transcriptional abundance plots of AsMYB TFs. (A) The heatmap showed the expression profile of AsMYB1R TFs; (B) The heatmap showed the expression profile of AsMYB2R and AsMYB3R TFs; (C) The heatmap showed the expression profile of 8 differential expression genes. Rows represent the different time samples (0–72 h), the columns represent the different AsMYB genes

Fig. 9

The RT-qPCR plots of 8 differentially expressed genes. Relative expression level plots of 8 AsMYB genes following PEG treatment as determined by RT-qPCR. The Y-axis and X-axis indicated relative expression level and six time points of PEG treatment, respectively. The relative expression level of genes at 0 h was taken as 1, and were calculated by normalization method. Mean ± SD (Standard Deviation) was obtained from three biological and three technical replicates. The error bars indicate standard deviation. Different letters indicate significant differences, and the same letters represent no significant differences at the 0.05 level

Fig. 10

Stomatal aperture, H₂O₂ content and GST activity plots. (A) The stomatal aperture state at 6 time points (0–72 h) of A. sativa; The size of scale bar is 10 μm. (B) The analytic result of H₂O₂ content. Mean ± SD (Standard Deviation) was obtained from six biological replicates. The error bars indicate standard deviation. Different letters indicate significant differences, and the same letters represent no significant differences at the 0.05 level; (C) The analytic result of GST activity. Mean ± SD (Standard Deviation) was obtained from six biological replicates. The error bars indicate standard deviation. Different letters indicate significant differences, and the same letters represent no significant differences at the 0.05 level

Fig. 11

Transcriptional abundance plots of GST genes. The heatmap showed the expression profile of AsMYB1R TFs. Rows represent the different time samples (0–72 h), the columns represent the different GST genes