MBW complexes impinge on anthocyanidin reductase gene regulation for proanthocyanidin biosynthesis in persimmon fruit

[EN] MBW protein complexes containing MYB, bHLH and WD40 repeat factors are known transcriptional regulators of secondary metabolites production such as proanthocyanidins and anthocyanins, and developmental processes such as trichome formation in many plant species. DkMYB2 and DkMYB4 (MYB-type), DkMYC1 (bHLH-type) and DkWDR1 (WD40-type) factors have been proposed by different authors to take part of persimmon MBW complexes for proanthocyanidin accumulation in immature fruit, leading to its characteristic astringent flavour with important agronomical and ecological effects. We have confirmed the nuclear localization of these proteins and their mutual physical interaction by bimolecular fluorescence complementation analysis. In addition, transient expression of DkMYB2, DkMYB4 and DkMYC1 cooperatively increase the expression of a persimmon anthocyanidin reductase gene (ANR), involved in the biosynthesis of cis-flavan-3-ols, the structural units of proanthocyanidin compounds. Collectively, these data support the presence of MBW complexes in persimmon fruit and suggest their coordinated participation in ANR regulation for proanthocyanidin production. This work was funded by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-FEDER (grant no. RF2013-00043-C02-02 and RTA2017-00011-C03-01). FG-M was funded by a fellowship co-financed by the Generalitat Valenciana and European Social Fund (2014 2020) (grant no. ACIF/2016/115). Gil Muñoz, F.; Sanchez Navarro, JA.; Besada Ferreiro, CM.; Salvador Perez, AA.; Badenes Catala, M.; Naval Merino, MDM.; Rios Garcia, G. (2020). MBW complexes impinge on anthocyanidin reductase gene regulation for proanthocyanidin biosynthesis in persimmon fruit. Scientific Reports. 10:1-11. https://doi.org/10.1038/s41598-020-60635-w Dixon, R. A., Xie, D.-Y. & Sharma, S. B. Proanthocyanidins–a final frontier in flavonoid research? New Phytol. 165, 9–28 (2005). Yonemori, K. & Matsushima, J. Property of development of the tannin cells in non-astringent type fruits of Japanese persimmon (Diospyros kaki) and its relationship to natural deastringency. J. Jpn. Soc. Hortic. Sci. 54, 201–208 (1985). Salvador, A. et al. Physiological and structural changes during ripening and deastringency treatment of persimmon fruit cv. ‘Rojo Brillante’. Postharvest Biol. Tec. 46, 181–188 (2007). Bernays, E. A., Driver, G. C. & Bilgener, M. Herbivores and plant tannins. In Advances in Ecological Research (eds. Begon, M., Fitter, A. H., F