Abstract
SummaryPlant MYB transcription factors control diverse biological processes, such as differentiation, development and abiotic stress responses. In this study, we characterized BplMYB46, an MYB gene from Betula platyphylla (birch) that is involved in both abiotic stress tolerance and secondary wall biosynthesis. BplMYB46 can act as a transcriptional activator in yeast and tobacco. We generated transgenic birch plants with overexpressing or silencing of BplMYB46 and subjected them to gain‐ or loss‐of‐function analysis. The results suggest that BplMYB46 improves salt and osmotic tolerance by affecting the expression of genes including SOD,POD and P5CS to increase both reactive oxygen species scavenging and proline levels. In addition, BplMYB46 appears to be involved in controlling stomatal aperture to reduce water loss. Overexpression of BplMYB46 increases lignin deposition, secondary cell wall thickness and the expression of genes in secondary cell wall formation. Further analysis indicated that BplMYB46 binds to MYBCORE and AC‐box motifs and may directly activate the expression of genes involved in abiotic stress responses and secondary cell wall biosynthesis whose promoters contain these motifs. The transgenic BplMYB46‐overexpressing birch plants, which have improved salt and osmotic stress tolerance, higher lignin and cellulose content and lower hemicellulose content than the control, have potential applications in the forestry industry.
Highlights
Plant growth and development are strongly influenced by various stresses, such as salinity, drought and extreme temperatures (Su et al, 2014)
MYBs bind to several cis-acting motifs, including the following: MBSI (T/C)AAC (G/T)G(A/C/T)(A/C/T), which is involved in cell cycle control and resistance to low temperatures (Ma et al, 2009; Prouse and Campbell, 2012); MBSII (A/G)(G/T)T(A/T)GGT(A/G), which is involved in regulating secondary cell wall biosynthesis (Kim et al, 2012); MBSIIG, ACC(A/T)ACC(A/C/T), which is related to flavonoid biosynthesis (Grotewold et al, 1994); MYBCORE, CAGTTA and CTGTTG, which are associated with drought tolerance (Ithal and Reddy, 2004); and AC-box, ACC(A/T)A(A/C) (T/C), which is related to secondary cell wall deposition (Zhong et al, 2013)
Green fluorescent signals from the 35S: BplMYB46-green fluorescent protein (GFP) transformed cells were detected in the nuclei, which were stained using DAPI
Summary
Plant growth and development are strongly influenced by various stresses, such as salinity, drought and extreme temperatures (Su et al, 2014). MYBs bind to several cis-acting motifs, including the following: MBSI (T/C)AAC (G/T)G(A/C/T)(A/C/T), which is involved in cell cycle control and resistance to low temperatures (Ma et al, 2009; Prouse and Campbell, 2012); MBSII (A/G)(G/T)T(A/T)GGT(A/G), which is involved in regulating secondary cell wall biosynthesis (Kim et al, 2012); MBSIIG, ACC(A/T)ACC(A/C/T), which is related to flavonoid biosynthesis (Grotewold et al, 1994); MYBCORE, CAGTTA and CTGTTG, which are associated with drought tolerance (Ithal and Reddy, 2004); and AC-box, ACC(A/T)A(A/C) (T/C), which is related to secondary cell wall deposition (Zhong et al, 2013)
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