Regulation of flavonoids in strawberry fruits by FaMYB5/FaMYB10 dominated MYB-bHLH-WD40 ternary complexes

Abstract

Anthocyanins endowing strawberry fruit red color are regulated by the MYB-bHLH-WD40 complex. By analyzing the MYBs involved in the flavonoid biosynthesis in strawberry, we found that R2R3-FaMYB5 promoted the content of anthocyanin and proanthocyanidins in strawberry fruits. Yeast two-hybrid and BiFC assays confirmed that MBW complexes connected with flavonoid metabolism were FaMYB5/FaMYB10-FaEGL3 (bHLH)-FaLWD1/FaLWD1-like (WD40). Transient overexpression and qRT-PCR analysis revealed that disparate MBW models hold different patterns in the regulation of flavonoid biosynthesis in strawberry fruits. Compared with FaMYB10, FaMYB5 and its dominant complexes showed a more specific regulatory range on strawberry flavonoid biosynthetic pathway, while FaMYB10 was more extensive. In addition, the complexes involved in FaMYB5 facilitated PAs accumulation primarily through the LAR tributary while FaMYB10 mainly by the ANR branch. FaMYB9 and FaMYB11 tremendously elicited the accumulation of proanthocyanidins by up-regulating the expression levels of both LAR and ANR, and also affected anthocyanin metabolism by changing the ratio of Cy3G and Pg3G which were constituted as two major anthocyanin monomers in strawberries. Our study also illustrated that FaMYB5-FaEGL3-FaLWD1-like directly targeted the promoters of F3′H, LAR, and AHA10 thus committing to flavonoid accumulation. These results allow the specific members involved in the MBW complex to be deciphered and provide new insights into the regulatory mechanisms of anthocyanins and proanthocyanidins regulated by the MBW complex.

Insights into the Coloring Mechanism of Dark-Red and Yellow Fruits in Sweet Cherry through Transcriptome and Metabolome Analysis

“…In apples, MdMYB90-like plays a key role in the regulation of anthocyanin biosynthesis [11]. In strawberry studies, yeast two-hybrid and BiFC assays also confirmed that the MBW complex can function in the flavonoid metabolic pathway in the form of FaMYB5/FaMYB10-FaEGL3 (bHLH)-FaLWD1/FaLWD1like (WD40) [12]. Similar findings were also presented in Arabidopsis thaliana and Norway spruce [13,14].…”

“…In particular, the four families of genes, MYB, bHLH, AP2, and WRKY, were significantly positively correlated with some of the differential genes (PAL, C4H, F3 H, LDOX, DFR, CHI) and metabolites (Rutin, Trifolin, Luteolin, Quercetin, Catechin, and Anthocyanins). MYB and bHLH are two important transcriptional proteins in plants, and they have regulatory roles in anthocyanin biosynthesis in fruits such as apples [45,46], strawberries [12,47], and grapes [48,49]. They are usually involved in the regulation of color accumulation in plants through the MBW ternary complex with WD40 proteins [50].…”

Unveiling phenylpropanoid regulation: the role of DzMYB activator and repressor in durian (Durio zibethinus) fruit

“…MYB TFs typically do not function in isolation; instead, they often form complexes with other proteins (Xu et al, 2015; Nemesio-Gorriz et al, 2017). Among the various groups of TFs capable of interacting with MYB TFs, bHLHs have been identi ed (Yue et al, 2023). Within the DzbHLHs, DzbHLH1 has been recognized for its potential to bind with the previously reported DzMYB1, a crucial contributor to avonoid biosynthesis (Weerawanich et al, 2024).…”

Involvement of a MYB Transcription Factor in Anthocyanin Biosynthesis during Chinese Bayberry (Morella rubra) Fruit Ripening

“…By increasing and inhibiting the activities of anthocyanin-related genes (MdF3H, MdDFR, and MdUFGT) and sugar-related genes (MdCWI1, MdVGT3, and MdTMT2), the MdMYB305-MdbHLH33-MdMYB10 complex balanced anthocyanin and sugar levels in red-fleshed apples [43,44]. FaMYB5 was also identified as an R2R3-MYB activator that is a component of the FaMYB5-FaEGL3-FaLWD1-like complex, which promotes anthocyanin and proanthocyanidin accumulation by directly targeting the F3'H and LAR promoters in strawberry [34,45].…”