Abstract
As one of the largest transcription factor families, MYB transcription factors are widely present, and they are involved in a diverse range of physiological activities in plants, such as leaf development. GAMYB genes belong to the R2R3-MYB subfamily, which includes the MYB33/65/101 gene, and these genes are studied well in seed germination and flowering, but their roles in leaf development are poorly understood. In the current study, we isolated a GAMYB transcription factor from pak choi, BcMYB101, and analyzed its characteristics and function. The sequence structure analysis indicated that BcMYB101 has a highly conserved R2R3 DNA-binding domain in the N-terminal region and three GAMYB-specific motifs (Box1, Box2, and Box3). The expression pattern of diverse tissues revealed that BcMYB101 has a higher transcript level in the petiole, leaf, root, and floral organs. Furthermore, the expression level was significantly elevated after GA (gibberellin) treatment, suggesting that the BcMYB101 response was positively regulated by GA. Subcellular localization exhibited that BcMYB101 was only present in the nuclear region, consistent with the characterization of the transcription factor. The overexpression of BcMYB101 elucidated that BcMYB101 increased leaf number and resulted in downward-curling cauline leaves. Moreover, the virus-induced BcMYB101 silencing displayed that BcMYB101 is involved in the regulation of curly leaves. Furthermore, we discovered that BcMYB101 has two trans-activation activities and one interaction protein, BcTCH4, using a trans-activation activity assay and a yeast two-hybrid assay, respectively. In this study, we firstly isolated the BcMYB101 gene and explored its function in leaf development, thereby providing a solid foundation for further research on the regulatory mechanism of leaf shape in Brassica or other species.
Highlights
Transcription factors mediate plant growth and development, as well as physiological metabolism, to adapt to changes in the external environment via regulating the expression of target genes at the transcriptional level
To further explore the regulatory network of the BcMYB101 protein, we used yeast two-hybrid assays to identify its trans-activation domain and to screen its possible interaction proteins; one candidate protein, BcTCH4, was found to interact with BcMYB101 in yeast. These findings extend our understanding of MYB101 in Cruciferae plants, suggesting that BcMYB101 acts as a nuclear-target protein, involved in gibberellin signaling and leaf development in pak choi
Multiple sequence alignment of the GAMYB and GAMYB-like proteins from Hordeum vulgare, Solanum lycopersicum, Oryza sativa, Zea mays, Vitis vinifera, Gossypium hirsutum, Theobroma cacao, Arabidopsis thaliana, and pak choi showed that the BcMYB101 protein contains a highly conserved R2R3 domain in the N-terminal portion and three GAMYB-specific conserved regions Box1, Box2, and Box3 (Figure 1A)
Summary
Transcription factors mediate plant growth and development, as well as physiological metabolism, to adapt to changes in the external environment via regulating the expression of target genes at the transcriptional level. The MYB superfamily, as one of the largest transcription factor families in plants, plays an important role in diverse biological functions, including the plant hormone and environmental factor response, the coloration of flesh and pericarp [7], cell cycle and cell differentiation regulation [8], anthocyanin formation and secondary metabolism [9], and the morphogenesis of organs such as leaves [4]. The v2MYB gene was the first discovered MYB transcription factor from the leukemia viruses AMV and E26 in bird, and the first plant MYB gene identified was ZmMYBC1 from Zea mays [10]. MYB transcripts are a hot topic in the field of botany research, and the research progress is rapid due to the numerous members and diverse functions
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