University of Cordoba identifies transcription factor responsible for red color in strawberries

A new transcription factor that regulates the production of anthocyanins responsible for the red color of strawberries during ripening has been characterized by a research group at the University of Cordoba. The ripening process of strawberries determines their quality, organoleptic properties, and preferences of consumers and insects that disperse the seeds, promoting future plant growth.

The Biotechnology and Plant Pharmacognosy research group, led by Juan Muñoz Blanco, has been studying the genetic regulation of strawberry ripening for years. They have identified a new protein, a transcription factor (FaMYB123), that activates or suppresses the expression of other genes involved in the control of the fruit’s red color.

The study, which is part of Félix J. Martínez-Rivas’s doctoral thesis, was published in The Plant Journal. This transcription factor is responsible for the production of anthocyanins, the pigments that give strawberries their characteristic red color.

(a) Phylogenetic tree of FaMYB123 and its known R2R3 MYB transcription factors. The tree was constructed with the software FigTree, using the neighbor joining method with 1000 bootstrap replicates. Numbers next to each node represent confidence percentages. The GenBank accession numbers are FaMYB123 (MW081987), LjTT2a (AB300033.2), LjTT2b (AB300034.2), LjTT2c (AB300035.1), TaMYB14 (JN049641.1), PtMYB134 (FJ573151.1), PhAN2 (AF146702.1), MdMYB1 (DQ886414.1), AtTT2 (NP_198405.1), VvMybPA1 (AM259485.1), FaMYB10 (EU155162.1), VvMYBPA2 (EU919682.1), DkMYB2 (AB503699.1), AcMYB123 (MH643775), DkMYB4 (AB503701.1), AtMYB12 (DQ224277.1), VvMYB4 (EF113078.1), FaMYB1 (AF401220.1), MdMYB11 (AAZ20431), FaMYB11 (AFL02461), FaMYB9 (AFL02460), MdMYB9 (ABB84757), VvMYBA1 (AB097923.1), and VvMYBA2 (AB097924.1). (b) Subcellular localization of FaMYB123 in Nicotiana benthamiana leaves. The leaves were agroinfiltrated with translational constructs 35S::GFP:FaMYB123 and with 35S::GFP as control. (a, c) Leaves infiltrated with Agrobacterium carrying plasmid 35S::GFP:FaMYB123. (d, f) Leaves infiltrated with 35S::GFP (d and f). GFP, green fluorescent protein; DAPI, 4′,6-diamidino-2-phenylindole (nucleic dye); MERGE, merged view of GFP and DAPI images. Credit: The Plant Journal (2023). DOI: 10.1111/tpj.16166

The research group validated their findings by creating a transgenic strawberry plant with repressed FaMYB123 expression, which resulted in decreased anthocyanin production and a less vibrant red color compared to normal fruit. However, FaMYB123 doesn’t work alone, as transcription factors usually function in combination with other factors. The study revealed that FaMYB123 interacts with another factor called FabHLH3, both of which contribute to increased anthocyanin production during strawberry ripening.

This study provides new insights into the regulation of strawberry ripening, which is crucial for Spain, Europe’s main producer of strawberries. The province of Huelva is a top producer of this fruit. Francisco Javier Molina Hidalgo, a member of the research team, stated that understanding the control of the ripening process, such as the red color of the fruit, enables genetic manipulation or the creation of new varieties in breeding programs.

Source: University of Córdoba

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