This study employed single-cell RNA sequencing (scRNA-seq) to analyze the cell heterogeneity of theanine metabolism and regulation in tea plant roots. The authors first identified 8 distinct cell clusters in the tea root, including xylem, epidermal, cortex/endodermal, phloem, pericycle, cambium, stem cell niche, and root cap cells.
The authors then investigated the cell-type-specific expression patterns of genes involved in nitrogen transport, amino acid metabolism, theanine biosynthesis, storage, and transport. They found that nitrogen uptake and assimilation genes were primarily expressed in the cortex, endodermis, and stele cells, while the theanine biosynthetic genes CsTSI and CsAlaDC showed differential enrichment in the pericycle and vasculature, respectively, suggesting a multicellular compartmentation of theanine synthesis.
The authors also identified the transcription factor CsLBD37 as a key regulator that co-controls theanine biosynthesis and lateral root development in tea plants. CsLBD37 was found to bind and repress the CsAlaDC promoter, thereby fine-tuning theanine synthesis in response to nitrogen levels.
Overall, this study provides novel insights into the cell-type-specific mechanisms underlying theanine metabolism and regulation in tea plant roots, offering a framework for understanding root-specific secondary metabolism in other plant systems.
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by Lin,S., Zhan... at www.biorxiv.org 01-17-2024
https://www.biorxiv.org/content/10.1101/2024.01.16.575853v1Deeper Inquiries