Genome-Wide Analysis of MYB Transcription Factors and Screening of MYBs Involved in the Red Color Formation in Rhododendron delavayi

Abstract

Flower color is one of the crucial traits of ornamental plants. Rhododendron delavayi Franch. is a famous ornamental plant species distributed in the mountain areas of Southwest China. This plant has red inflorescence and young branchlets. However, the molecular basis of the color formation of R. delavayi is unclear. In this study, 184 MYB genes were identified based on the released genome of R. delavayi. These genes included 78 1R-MYB, 101 R2R3-MYB, 4 3R-MYB, and 1 4R-MYB. The MYBs were divided into 35 subgroups using phylogenetic analysis of the MYBs of Arabidopsis thaliana. The members of the same subgroup in R. delavayi had similar conserved domains and motifs, gene structures, and promoter cis-acting elements, which indicate their relatively conserved function. In addition, transcriptome based on unique molecular identifier strategy and color difference of the spotted petals, unspotted petals, spotted throat, unspotted throat, and branchlet cortex were detected. Results showed significant differences in the expression levels of R2R3-MYB genes. Weighted co-expression network analysis between transcriptome and chromatic aberration values of five types of red samples showed that the MYBs were the most important TFs involved in the color formation, of which seven were R2R3-MYB, and three were 1R-MYB. Two R2R3-MYB (DUH019226.1 and DUH019400.1) had the highest connectivity in the whole regulation network, and they were identified as hub genes for red color formation. These two MYB hub genes provide references for the study of transcriptional regulation of the red color formation of R. delavayi.

Genome-Wide Identification and Characterization of MYB Gene Family and Analysis of Its Sex-Biased Expression Pattern in Spinacia oleracea L.

“…From an evolutionary point of view, studies have shown that 2R-MYB transcription factors are distributed in fungi, animals, and plants, indicating that 2R-MYB transcription factors are relatively ancient and conserved [60]. The abundance of 2R-MYB genes is predominant in both A. thaliana and spinach, and this discovery has also been found in Rhododendron delavayi [61], mainly because the 2R-MYB transcription factor is amplified in higher plants, increasing the number of 2R-MYB genes. In combination with an evolutionary perspective, a relatively conservative structure that has a relatively conserved function may be related to the stability of the plant's genetic material and its ability to adapt to the environment with more favorable traits [62].…”

Anthocyanin Metabolite and Transcriptome Sequencing Analysis Reveals White Flowers in Rhododendron dauricum var. albiflorum

“…Apart from structural genes, anthocyanin biosynthesis is also regulated by several TFs, in which MYB, bHLH, and WD repeats form the MBW ternary complex to regulate transcription levels of the structural genes that participate in the anthocyanin and proanthocyanidin biosynthesis pathways [56]. MYB plays a critical role in MBW complexes for its tissue-specific expression and binding to specific DNA sequences [57]. Some studies have shown that MYB can enhance or inhibit anthocyanin biosynthesis.…”