Four HD-ZIPs are involved in banana fruit ripening by activating the transcription of ethylene biosynthetic and cell wall-modifying genes
Four MaHDZs are possibly involved in banana fruit ripening by activating the transcription of genes related to ethylene biosynthesis and cell wall degradation, such as MaACO5, MaEXP2, MaEXPA10, MaPG4 and MaPL4.
The homeodomain-leucine zipper (HD-ZIP) proteins represent plant-specific transcription factors, which contribute to various plant physiological processes. However, little information is available regarding the association of HD-ZIPs with banana fruit ripening. In this study, we identified a total of 96 HD-ZIP genes in banana genome, which were divided into four different groups consisting of 35, 31, 9 and 21 members in the I, II, III and IV subfamilies, respectively. The expression patterns of MaHDZ genes during fruit ripening showed that MaHDZI.19, MaHDZI.26, MaHDZII.4 and MaHDZII.7 were significantly up-regulated in the ripening stage and thus suggested to be potential regulators of banana fruit ripening. Furthermore, MaHDZI.19, MaHDZI.26, MaHDZII.4 and MaHDZII.7 were found to localize exclusively in the nucleus and exhibit transcriptional activation capacities. Importantly, MaHDZI.19, MaHDZI.26, MaHDZII.4 and MaHDZII.7 stimulated the transcription of several ripening-related genes including MaACO5 related to ethylene biosynthesis, MaEXP2, MaEXPA10, MaPG4 and MaPL4 were associated with cell wall degradation, through directly binding to their promoters. Taken together, our findings expand the functions of HD-ZIP transcription factors and identify four MaHDZs likely involved in regulating banana fruit ripening by activating the expression of genes related to ethylene biosynthesis and cell wall modification, which may have potential application in banana molecular breeding.
KeywordsBanana HD-ZIP Fruit ripening Transcriptional regulation
Electrophroretic mobility shift assay
Green fluorescent protein
Quantitative real-time polymerase chain reaction
We thank Dr. George P. Lomonossoff (John Innes Centre, Norwich Research Park) for the generous gift of pEAQ vectors. This work was financially supported by the grants from the Natural Science Foundation of China (Grant no. 31830071), and China Agriculture Research System (Grant no. CARS-31-11).
Author contribution statement
YYY performed the experiments, interpreted the results and wrote the article; YYY and WS analyzed the data and performed statistical analyses; JFK and JYC contributed to experiment design and manuscript editing; WJL designed and coordinated the experiments, and revised and improved the manuscript; WJL is responsible for the manuscript as a whole.
Compliance with ethical standards
Conflict of interest
The authors have no conflicts of interest to declare.