VvMYB14 participates in melatonin-induced proanthocyanidin biosynthesis by upregulating expression of VvMYBPA1 and VvMYBPA2 in grape seeds

Abstract

This work demonstrated that melatonin increases continuously in seeds, particularly seed coats, during berry ripening. Exogenous melatonin treatments significantly increased the proanthocyanidin (PA) content, partially through ethylene signaling, in seed coats. VvMYB14 expression exhibited patterns similar to melatonin accumulation over time, which was largely induced by melatonin treatment in seed coats during berry ripening. Additionally, VvMYB14 bound to the MBS element of the VvMYBPA1 promoter to activate expression. VvMYB14 overexpression largely upregulated expression of VvMYBPA1, VvMYBPA2 and VvLAR1 and increased the PA content in grape seed-derived calli. Similar increases in AtTT2 and AtBAN expression and PA content were found in VvMYB14-overexpressing Arabidopsis seeds. It was also observed that VvMYB14 overexpression increased ethylene production and thereby induced expression of VvERF104, which bound to the ERF element of the VvMYBPA2 promoter and activated its expression. Additionally, VvERF104 suppression reduced the VvMYB14 overexpression-induced increases in expression of VvMYBPA2 and VvLAR1 and PA content. Further experiments revealed that melatonin-induced increases in the expression of VvMYBPA1, VvMYBPA2, VvERF104 and VvLAR1 and PA accumulation were significantly reduced in VvMYB14-suppressing grape calli and leaves. Collectively, VvMYB14 mediates melatonin-induced PA biosynthesis by directly transactivating VvMYBPA1 expression and indirectly upregulating VvMYBPA2 expression via VvERF104.

Acknowledgements

This study was financially supported by National Key R&D Program of China (2018YFD1000200), Agriculture Improved Variety Project of Shandong Province (2020LZGC008), Major Project of Science and Technology of Shandong Province (2022CXGC010605), Fruit Industrial Technology System of Shandong Province (SDAIT-06-03) and the National Natural Science Foundation of China (31872068 and 32072537).

Author contributions

Y.Y. and X.Z. conceived and designed the research; X.Z., W.M., F.W. and Z.F. performed the experiments; X.G. and S.G. analyzed the data; and Y.Y. wrote the manuscript. All authors read and approved the manuscript.

Data availability

All the experimental data are available and accessible via the main text and/or the supplemental data.

Conflict of interest

The authors declare that they have no conflicts of interest.

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