Systematic Analysis and Functional Characterization of R2R3-MYB Genes in Scutellaria baicalensis Georgi

Abstract

R2R3-MYB transcription factors participate in multiple critical biological processes, particularly as relates to the regulation of secondary metabolites. The dried root of <i>Scutellaria baicalensis</i> Georgi is a traditional Chinese medicine and possesses various bioactive attributes including anti-inflammation, anti-HIV, and anti-COVID-19 properties due to its flavonoids. In the current study, a total of 95 <i>R2R3-MYB</i> genes were identified in <i>S. baicalensis</i> and classified into 34 subgroups, as supported by similar exon-intron structures and conserved motifs. Among them, 93 <i>R2R3-SbMYB</i><i>s</i> were mapped onto nine chromosomes. Collinear analysis revealed that segmental duplications were primarily responsible for driving the evolution and expansion of the <i>R2R3-SbMYB</i> gene family. Synteny analyses showed that the ortholog numbers of the <i>R2R3-MYB</i> genes between <i>S. baicalensis</i> and other dicotyledons had a higher proportion compared to that which is found from the monocotyledons. RNA-seq data indicated that the expression patterns of <i>R2R3-SbMYBs</i> in different tissues were different. Quantitative reverse transcriptase-PCR (qRT-PCR) analysis showed that 36 <i>R2R3-SbMYBs</i> from different subgroups exhibited specific expression profiles under various conditions, including hormone stimuli treatments (methyl jasmonate and abscisic acid) and abiotic stresses (drought and cold shock treatments). Further investigation revealed that <i>Sb</i>MYB18/32/46/60/70/74 localized in the nucleus, and <i>Sb</i>MYB18/32/60/70 possessed transcriptional activation activity, implying their potential roles in the regulatory mechanisms of various biological processes. This study provides a comprehensive understanding of the <i>R2R3-SbMYBs</i> gene family and lays the foundation for further investigation of their biological function.