The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms.

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Fosfomycin disodium salt (FDS), which is a water-soluble extract, is a bactericidal drug used to inhibit the synthesis of cells. Moreover, it has been found to be effective in the treatment of urinary tract infections. The present study was conducted to investigate the melanogenesis-stimulating effect of FDS in B16F10 cells. Several experiments were performed on B16F10 cells: the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, the melanin content assay, the cellular tyrosinase activity assay, and Western blotting. FDS upregulated the activity of tyrosinase in a dose-dependent manner at a wide concentration range of 0–1 mg/mL, which showed no cytotoxicity. It also increased the melanin content and the activity of the microphthalmia-associated transcription factor (MITF), tyrosinase related protein 1 (TRP-1), and tyrosinase related protein 2 (TRP-2) enzymes in a dose-dependent manner. Western blotting results showed that FDS clearly upregulated the phosphorylation of c-Jun N-terminal kinases (JNK) and p38 pathways. These data are clear evidence of the melanogenesis-inducing effect of FDS in B16F10 murine melanoma cells.

The original version of this Article contained a typographical error in the spelling of the author Matthew Gilliham, which was incorrectly given as Matthew Gillham. This has now been corrected in both the PDF and HTML versions of the Article.