Ca²⁺ suppresses stone cell through PuNAC21-PuDof2.5 module that regulates lignin biosynthesis in pear fruits

Abstract

Lignin deposition in stone cells is a critical factor that limits pear fruit quality, affecting their market value. Calcium ions (Ca ²⁺) play an essential role in lignin biosynthesis during fruit stone cell production. However, the genetic mechanisms underlying the Ca ²⁺ regulated lignin synthesis in stone cell formation are not fully understood. In this study, we identified an NAC transcription factor (TF) PuNAC21, which is repressed by CaCl₂ treatment. PuNAC21 bound directly to the lignin biosynthesis gene peroxidase 42-like (PuPRX42-like) promoter, Ca²⁺ reduced pear fruit stone cell production dependent on PuNAC21 positively regulating PuPRX42-like expression. Furthermore, PuNAC21 directly regulated the expression of PuDof2.5, a TF involved in lignin biosynthesis by binding to PuPRX42-like and caffeoyl-CoA-O-methyltransferase 1(PuCCoAOMT1) promoters. Moreover, PuNAC21 interacted with PuDof2.5 to form a transcriptional regulatory module, lowering the transcription of PuPRX42-like and PuCCoAOMT1 after Ca²⁺ treatment, which contributed to decrease pear stone cells production. Our results revealed Ca²⁺-induced PuNAC21-PuDof2.5-PuPRX42-like/PuCCoAOMT1 regulatory module inhibited lignin biosynthesis, giving important insights into reducing the stone cell content in pears via molecular breeding.

Acknowledgments

The authors gratefully acknowledge the Prof. Aide Wang (Shenyang Agricultural University, Shenyang, China) and Prof. Zhifu Guo (Shenyang Agricultural University, Shenyang, China) for providing the vectors. This study was supported by the Earmarked Fund for the China Agriculture Research System (CARS-28), National Key Research and Development Program of China (2022YFD1600500), and the Key Technology of Calcium-regulated Quality Development in ‘Nanguoli’ Pear (01042017005). We acknowledge TopEdit (http://www.topeditsci.com) for editing this manuscript.

Author Contributions

G.D. conceived and planned the study. S.G. and M.Y. collected the samples. H.Z. performed most of the experiments. M.X., T.W., and X.L. helped conduct some of the experiments. G.D. and H.Z. wrote the manuscript. All authors read and approved the final manuscript.

Data availability

The RNA-seq reads have been deposited in the National Center for Biotechnology Information under project no. PRJNA797117. Sequence data from this article can be found in the NCBI data libraries under accession numbers: PuPRX42-like (NM001302306.1), PuDof2.5 (XM009336089.3), PuCCoAOMT1 (XM009346792.3), and PuNAC21 (XM048574137.1).

Conflict of interest statement:

The authors declare no conflict of interest.

Supplementary data

Supplementary data is available at Horticulture Research online.

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