Characterization of a KANADI-like transcription factor that suppresses pear anthocyanin biosynthesis

Abstract

Anthocyanins are important specialized fruit metabolites and major pigments, whose abundance depends on co-regulation of activators and repressors, primarily transcription factors (TFs) of the MYB family. Herein, a KANADI-like TF PuKAN4 was characterized in pear. This TF could be transcriptionally up-regulated by the anthocyanin-related R2R3-MYBs PuMYB10/PuMYB114 and exhibited high expression within red-skinned pears. Interestingly, PuKAN4 repressed anthocyanin biosynthesis in transiently overexpressed pear fruit, and stable transformation in pear calli and tobacco plants. The PuKAN4 had a conserved EAR repression domain in C-terminal, while the repression function of PuKAN4 could be offset by a transcription activation domain VP64. The dual luciferase analysis proved that PuMYB114/PuMYB10 up-regulated expression of PuKAN4. Furthermore, the PuKAN4 could physically interact with PuMYB10/PuMYB114 and did not affect the combination of MYB10/MYB114-bHLH3, as demonstrated by Y2H, pull-down and firefly luciferase complementation. Thus, the PuKAN4 should play the role of active repressor, the formation of PuKAN4-PuMYB10/PuMYB114-PubHLH3 complex inhibited pear anthocyanin biosynthesis. Our findings unveiled an activator-and-repressor feedback loop between PuMYB114/PuMYB10 and PuKAN4, which possibly balance biosynthesis activity and prevents over-accumulation of phenylpropanoids.

Acknowledgments

This work was funded by the National Science Foundation of China (31820103012), the Earmarked Fund for China Agriculture Research System (grant no. CARS-28), the Earmarked Fund for Jiangsu Agricultural Industry Technology System (JATS [2023]412), Jiangsu Specially-Appointed Professor Project (2018), and Jiangsu Agricultural Science and Technology Innovation Fund [Grant No. CX(23)3016].

Author Contributions

J.W. conceived and designed the experiments. W.L.W. wrote the paper. W.L.W., G.S.C. and B.B.C. conducted the experiment. K.L-W., M.F.Q., R.Z.W., and J.M.L. offered professional assistance in conducting experimentation and analyzing data, and revising the manuscript. S.F.S. and J.C.L. performed sample collection and other preparatory work. J.W., K.L-W., R.V.E., and A.C.A. designed aspects of the study and revised the paper. All authors read and approved the final manuscript.

Data availability

The data generated for this study have been deposited in the United States National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) under the accession number PRJNA814481.

Conflict of interest statement

All authors declare no conflicts of interest.

Supplementary data

Supplementary data is available at Horticulture Research online.

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