Abstract
R2R3-MYB proteins play role in plant development, response to biotic and abiotic stress, and regulation of primary and secondary metabolism. Little is known about the R2R3-MYB proteins in Scutellaria baicalensis which is an important Chinese medical plant. In this paper, nineteen putative SbMYB genes were identified from a S. baicalensis cDNA library, and eleven R2R3-MYBs were clustered into 5 subgroups according to phylogenetic reconstruction. In the S. baicalensis leaves which were sprayed with GA3, SbMYB2 and SbMYB7 had similar expression pattern with SbPALs, indicating that SbMYB2 and SbMYB7 might be involved in the flavonoid metabolism. Transactivation assay results showed that SbMYB2 and SbMYB7 can function as transcriptional activator. The expression of several flavonoid biosynthesis-related genes were induced or suppressed by overexpression of SbMYB2 or SbMYB7 in transgenic tobacco plants. Consistent with the change of the expression of NtDH29 and NtCHI, the contents of dicaffeoylspermidine and quercetin-3,7-O-diglucoside in SbMYB2-overexpressing or SbMYB7-overexpressing transgenic tobacco plants were decreased. The transcriptional level of NtUFGT in transgenic tobacco overexpressing SbMYB7 and the transcriptional level of NtHCT in SbMYB2-overexpressing tobacco plants were increased; however the application of GA3 inhibited the transcriptional level of these two genes. These results suggest that SbMYB2 and SbMYB7 might regulate the flavonoid biosynthesis through GA metabolism.
Highlights
MYB proteins present in all eukaryotes and play roles in a variety of plant-specific processes, as evidenced by their extensive functional characterization in Arabidopsis (Arabidopsis thaliana) [1], maize (Zea mays) [2], rice (Oryza sativa) [3], petunia (Petunia hybrida) [4], grapevine (Vitis vinifera L.) [5], poplar (Populus tremuloides) [6] and apple (Malus domestica) [7]
We isolated nineteen full-length SbMYB genes from a S. baicalensis cDNA library, and eleven R2R3-MYBs with conserved R2R3 domain were divided into 5 subgroups based on the conservation of the DNA binding domain of Arabidopsis MYB proteins
The transcriptional levels of SbMYB2 and SbMYB7 which belong to subgroup 14 were decreased by GA3 treatment, whereas the expression of SbMYB8 which belongs to subgroups 6 was increased after spraying exogenous GA
Summary
MYB proteins present in all eukaryotes and play roles in a variety of plant-specific processes, as evidenced by their extensive functional characterization in Arabidopsis (Arabidopsis thaliana) [1], maize (Zea mays) [2], rice (Oryza sativa) [3], petunia (Petunia hybrida) [4], grapevine (Vitis vinifera L.) [5], poplar (Populus tremuloides) [6] and apple (Malus domestica) [7]. Most plant MYB proteins belong to the R2R3-MYB subfamily [8], and the Arabidopsis R2R3-type MYB factors encoded by the AtMYB genes have been categorized into 22 subgroups on the basis of the conserved amino acid sequence motifs [9]. Arabidopsis R2R3-MYB proteins have been found to be involved in primary and secondary metabolism, cell fate and identity, developmental processes and responses to biotic and abiotic stresses [10]. Some R2R3-MYB proteins are involved in the regulation of the flavonoid biosynthetic pathway [11]. Overexpression of AtMYB75/PAP1 and AtMYB90/PAP2 resulted in a massive activation of phenylpropanoid biosynthetic genes and enhanced the accumulation of lignin, hydroxycinnamic acid esters, and purple anthocyanins [12]. AtMYB4 was shown to negatively regulate the expression of cinnamate 4-hydroxylase gene, repress the synthesis of sinapoyl malate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
