Multi-omics analyses reveal the difference of stone cell distribution in pear fruit.

Abstract

Stone cells are the brachysclereid cells in pear (Pyrus) fruit, consisting almost entirely of lignified secondary cell walls. They are distributed mainly near the fruit core and spread radially in the whole fruit. However, the development of stone cells has not been comprehensively characterized. The regulation of stone cell formation on transcriptomic, proteomic and metabolomic levels remains largely unknown. In this study, we performed phenomic analysis on the stone cells and their associated vascular bundles distributed near the fruit cores. Transcriptomic, proteomic and metabolomic analyses revealed significantly positive regulation of biological processes, which contributed to the lignification and lignin deposition in stone cells near the fruit core, including sucrose metabolism, phenylalanine, tyrosine, tryptophan, and phenylalanine biosynthesis. We then found many metabolites generated from the phenylpropanoid pathway, contributing to the cell wall formation of stone cells near the fruit core. Furthermore, we identified a key transcription factor, PbbZIP48, which was significantly highly expressed near the fruit core and was then proven to regulate the lignin biosynthesis in stone cells. In conclusion, we provide new insights into understanding the mechanism of lignified stone cell formation near the pear fruit core at multi-omics levels.