Phosphate availability affects the tonoplast localization of PLD 2, an Arabidopsis thaliana phospholipase D

Under phosphate deprivation, higher plants change their lipid composition and recycle phosphate from phospholipids. A phospholipase D, PLD zeta 2, is involved in this recycling and in other cellular functions related to plant development. We investigated the localization of Arabidopsis PLD zeta 2 by cell fractionation and in vivo GFP confocal imaging. AtPLD zeta 2 localizes to the tonoplast and the Nter regulatory domain is sufficient for its sorting. Under phosphate deprivation, AtPLD zeta 2 remains located in the tonoplast but its distribution is uneven. We observed PLD zeta 2-enriched tonoplast domains preferentially positioned close to mitochondria and beside chloroplasts. In absence of PLD zeta 2, membrane developments were visualized inside vacuoles

Chemical inhibitors of monogalactosyldiacylglycerol synthases in Arabidopsis thaliana.

International audienceMonogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the main lipids in photosynthetic membranes in plant cells. They are synthesized in the envelope surrounding plastids by MGD and DGD galactosyltransferases. These galactolipids are critical for the biogenesis of photosynthetic membranes, and they act as a source of polyunsaturated fatty acids for the whole cell and as phospholipid surrogates in phosphate shortage. Based on a high-throughput chemical screen, we have characterized a new compound, galvestine-1, that inhibits MGDs in vitro by competing with diacylglycerol binding. Consistent effects of galvestine-1 on Arabidopsis thaliana include root uptake, circulation in the xylem and mesophyll, inhibition of MGDs in vivo causing a reduction of MGDG content and impairment of chloroplast development. The effects on pollen germination shed light on the contribution of galactolipids to pollen-tube elongation. The whole-genome transcriptional response of Arabidopsis points to the potential benefits of galvestine-1 as a unique tool to study lipid homeostasis in plants