RRC ID 73363
Author Tatsumi K, Ichino T, Isaka N, Sugiyama A, Moriyoshi E, Okazaki Y, Higashi Y, Kajikawa M, Tsuji Y, Fukuzawa H, Toyooka K, Sato M, Ichi I, Shimomura K, Ohta H, Saito K, Yazaki K.
Title Excretion of triacylglycerol as a matrix lipid facilitating apoplastic accumulation of a lipophilic metabolite shikonin.
Journal J Exp Bot
Abstract Plants produce a large variety of lipophilic metabolites, many of which are secreted by cells and accumulated in apoplasts. These compounds often play a role to protect plants from environmental stresses. However, little is known about how these lipophilic compounds are secreted into apoplastic spaces. In this study, we used shikonin-producing cultured cells of Lithospermum erythrorhizon as an experimental model system to analyze the secretion of lipophilic metabolites, taking advantage of its high production rate and the clear inducibility in culture. Shikonin derivatives are lipophilic red naphthoquinone compounds that accumulate exclusively in apoplastic spaces of these cells and also in the root epidermis of intact plants. Microscopic analysis showed that shikonin is accumulated in the form of numerous particles on the cell wall. Lipidomic analysis showed that L. erythrorhizon cultured cells secrete an appreciable portion of triacylglycerol (24-38% of total triacylglycerol), composed predominantly of saturated fatty acids. Moreover, in vitro reconstitution assay showed that triacylglycerol encapsulates shikonin derivatives with phospholipids to form lipid droplet-like structures. These findings suggest a novel role for triacylglycerol as a matrix lipid, a molecular component involved in the secretion of specialized lipophilic metabolites.
Volume 74(1)
Pages 104-117
Published 2023-1-1
DOI 10.1093/jxb/erac405
PII 6759617
PMID 36223279
MeSH Gene Expression Regulation, Plant Lipids Naphthoquinones* / metabolism Plant Proteins* / metabolism
IF 5.908
Arabidopsis / Cultured plant cells, genes rpc00001