Phenol homeostasis is ensured in vanilla fruit by storage under solid form in a new chloroplast-derived organelle, the phenyloplast

Abstract

A multiple cell imaging approach combining immunofluorescence by confocal microscopy, fluorescence spectral analysis by multiphotonic microscopy, and transmission electron microscopy identified the site of accumulation of 4-O-(3-methoxybenzaldehyde) β-d-glucoside, a phenol glucoside massively stockpiled by vanilla fruit. The glucoside is sufficiently abundant to be detected by spectral analysis of its autofluorescence. The convergent results obtained by these different techniques demonstrated that the phenol glucoside accumulates in the inner volume of redifferentiating chloroplasts as solid amorphous deposits, thus ensuring phenylglucoside cell homeostasis. Redifferentiation starts with the generation of loculi between thylakoid membranes which are progressively filled with the glucoside until a fully matured organelle is obtained. This peculiar mode of storage of a phenolic secondary metabolite is suspected to occur in other plants and its generalization in the Plantae could be considered. This new chloroplast-derived organelle is referred to as a ‘phenyloplast’.

Deciphering the Theobroma cacao self-incompatibility system: from genomics to diagnostic markers for self-compatibility

“…Immunostaining was performed on 8-μm paraffin sections of unpollinated ovaries and SC-pollinated or SI-pollinated ovaries (8–24 h) after fixation in 3% paraformaldehyde/0.1% Triton X-100 in phosphate buffer and embedding in paraplast blocks ( Brillouet et al , 2014 ).…”

On the Role of Chloroplasts in the Polymerization of Tannins in Tracheophyta: A Monograph

“…vine grown at high altitude under high UV-B radiation [13]). Such dilations were also observed in vanilla chloroplasts forming 4-O-(3-methoxybenzaldehyde) glucoside [14].…”

Stereochemical identification of glucans by oligothiophenes enables cellulose anatomical mapping in plant tissues

“…Since our multi-laser/multi-detector method distinctly separates fluorescence signals, we analysed whether intrinsic tissue fluorescence can be used to our advantage, to provide further details on the anatomical location of chemical constituents in plants. The green pigment chlorophyll, a molecule essential for plant photosynthesis, is known to fluoresce when excited at 440 nm and 660 nm 17 , 18 . We therefore excited the h-FTAA stained onion scale at 635 nm, while performing multi-laser/multi-detector analysis on the region containing the vascular bundle.…”

“…4h ). The intracellular compartments are most likely chloroplasts, since this organelle is characterised by its high concentration of chlorophyll 17 . Lignin is another plant constituent that fluoresce when excited by UV and visible light 19 – 23 .…”