Interaction of AcMADS68 with transcription factors regulates anthocyanin biosynthesis in red-fleshed kiwifruit

Abstract

In red-fleshed kiwifruit, anthocyanin pigmentation is a crucial commercial trait. The MYB-bHLH-WD40 (MBW) complex and other transcription factors regulate its accumulation. Herein, a new SEP gene, AcMADS68, was identified as a regulatory candidate for anthocyanin biosynthesis in the kiwifruit by transcriptome data and bioinformatic analyses. AcMADS68 alone could not induce the accumulation of anthocyanin both in Actinidia arguta fruit and tobacco leaves. However, in combination with AcMYBF110, AcMYB123, and AcbHLH1, AcMADS68 co-overexpression increased anthocyanin biosynthesis, whereas its silencing reduced anthocyanin accumulation. The results of the dual-luciferase reporter, firefly luciferase complementation, yeast two-hybrid and co-immunoprecipitation assays showed that AcMADS68 could interact with both AcMYBF110 and AcMYB123 but not with AcbHLH1, thereby co-regulating anthocyanin biosynthesis by promoting the activation of the target genes, including AcANS, AcF3GT1, and AcGST1. Moreover, AcMADS68 also could activate the promoter of AcbHLH1 surported by dual-luciferase reporter and yeast one-hybrid assays, thereby further amplifying the regulation signals from the MBW complex, thus resulting in enhanced anthocyanin accumulation in the kiwifruit. These findings may facilitate better elucidation of various regulatory mechanisms underlying anthocyanin accumulation and contribute to the quality enhancement of red-fleshed kiwifruit.

Acknowledgements

This work was supported by grants from the National Natural Science Foundation (Grant No. 32102312), the modern agricultural industry technology system (Grant No. CARS-26), and the National Forestry and Grassland Extension Project (Grant No. K3130219012). The authors thank Prof. Wangjin Lu for providing the pBD-related vectors.

Author contributions

Y.L., G.L., Y.Y., and K.M. performed experiments and analyses, and Y.L. wrote and revised the manuscript. X.R. and M.L. helped revise the manuscript. Z.L. designed the experiments and revised the manuscript. All authors have participated in this research and approved the final manuscript.

Data availability

The sequence data of AcMADS68 were submitted to the NCBI database (accession number ON175934). The other data for this article are available in the article or in its online supplementary material.

Conflict of interest

The authors declare no potential conflicts of interest.

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