Ethylene response factors Pp4ERF24 and Pp12ERF96 regulate blue light-induced anthocyanin biosynthesis in ‘Red Zaosu’ pear fruits by interacting with MYB114
Pp4ERF24 and Pp12ERF96 fine tune blue light-induced anthocyanin biosynthesis via interacting with PpMYB114 and promoting the interaction between PpMYB114 and PpbHLH3, which enhances the expression of PpMYB114-induced PpUFGT.
The red coloration of pear fruit is attributed to anthocyanin accumulation, which is transcriptionally regulated by the MYB-bHLH-WD40 complex. A number of ethylene response factors (ERF) have been identified to regulate anthocyanin biosynthesis in different plants. In pear, several ERF transcription factor genes were identified to be potentially involved in the light-induced anthocyanin biosynthesis according to transcriptome data. But the molecular mechanism of these ERFs underlying the regulation of anthocyanin accumulation is unknown. In this study, exposure of ‘Red Zaosu’ pear, a mutant of ‘Zaosu’ pear, to blue light significantly induced the anthocyanin accumulation by increasing the expression levels of anthocyanin biosynthetic genes. Gene expression analysis confirmed that the expression of Pp4ERF24 and Pp12ERF96 genes were up-regulated in the process of blue light-induced anthocyanin biosynthesis. Yeast two-hybrid and bimolecular fluorescence complementation assay revealed that Pp4ERF24 and Pp12ERF96 interacted with PpMYB114, but not with PpMYB10. Bimolecular fluorescence complementation assay demonstrated that the interaction between these two ERFs and PpMYB114 enhanced the interaction between PpMYB114 and PpbHLH3. Further analysis by dual luciferase assay verified that these two ERFs increased the up-regulation of PpMYB114-mediated PpUFGT expression. Furthermore, co-transformation of Pp12ERF96 with PpMYB114 and PpbHLH3 in tobacco leaves led to enhanced anthocyanin accumulation. Transient overexpression of Pp4ERF24 or Pp12ERF96 alone in ‘Red Zaosu’ pear fruit also induced anthocyanin biosynthesis in pear peel. Our findings provide insights into a mechanism involving the synergistic interaction of ERFs with PpMYB114 to regulate light-dependent coloration and anthocyanin biosynthesis in pear fruits.
KeywordsAnthocyanin Pear (Pyrus) ERF MYB Blue light
Ethylene response factor
UDP-glucose: flavonoid 3-glucosyltransferase
Early biosynthetic gene
Late biosynthetic gene
Phenylalanine ammonia lyase
Days after full bloom
This study was supported by the National Natural Science Foundation of China (Grant Nos. 31471852 to YT and 31772272 to SB) and the Earmarked Fund for China Agriculture Research System (CARS-28).
JN, SB, and YT conceived and planned the study. RT and LY helped collect samples and extracted the total RNA. JN and YZ completed the qPCR, vector construction, and bioinformatics analysis. JN and LG conducted the Y2H, BiFC, dual luciferase, firefly luciferase complementation imaging assays and the transient transformation assay of gene function in tobacco leaves and ‘Red Zaosu’ fruits. JN, SB, MQ and YT wrote the manuscript. All of the authors read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interest.
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