The eTM-miR3699-MAN7 mediated cell wall degradation in regulating embryogenic cell formation during the early stage of somatic embryogenesis in apple

Abstract

Somatic embryogenesis (SE) in plants requires the prior formation of embryogenic cells in plants. The remodeling of the cell wall in mature somatic cells is a prerequisite for embryogenic cell formation. However, the mechanism of this process remains unelucidated. In this study, eTM3699, miR3699, and MANNAN7 (MAN7) were identified as key regulators of embryogenic cell formation through whole-transcriptome sequencing. The dual-luciferase reporter assays and GUS histochemical staining assays, were used to identified the regulatory network of eTM3699-miR3699-MdMAN7. The overexpression and CRISPR/Cas9-mediated transgenic assays were used for functional analysis of miR3699 and MdMAN7. MdMAN7 overexpression can enhance the activity of β-mannanase, induce hemicellulose degradation, reshape the cell wall of highly differentiated somatic cells, and relieve the restriction on cell differentiation and division, ultimately positively regulating the embryogenic cell formation. Specifically, the overexpression of MdMAN7 can significantly improve the efficiency and shorten the induction cycle of SE. miR3699 acted by negatively regulating MdMAN7. In addition, eTM3699 were identified as endogenous target mimics of miR3699 that bind to miR3699 to prevent cleavage of MdMAN7 and thereby positively regulate embryogenic cell formation. In conclusion, our results elucidate the mechanism of eTM-miR3699-MAN7 module regulating embryogenic cell formation during the early stage of SE in apple.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant no. 32401657), China Postdoctoral Science Foundation (2024 M762643), and Chinese Universities Scientific Fund (2452023085).

Authors contributions

H.L. and Y.Y. conceived and designed the experiments. Y.W. and M.C. performed the experiments and analyzed the data. X.Z. and J.W. constructed the various vectors and provided the plant materials. J.T. analyzed the data.

Data availability

The transcriptome data involved in this study have been uploaded to NCBI under number PRJNA1296799.

Conflicts of interest statement

The authors declare no competing interests.

Supplementary material

Supplementary material is available at Horticulture Research online.

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