Exposure of lycopersicon esculentum to microcystin-LR: effects in the leaf proteome and toxin translocation from water to leaves and fruits

摘要

Natural toxins such as those produced by freshwater cyanobacteria have beenregarded as an emergent environmental threat. However, the impact of these watercontaminants in agriculture is not yet fully understood. The aim of this work was toinvestigate microcystin-LR (MC-LR) toxicity in Lycopersicon esculentum and the toxinaccumulation in this horticultural crop. Adult plants (2 month-old) grown in a greenhouseenvironment were exposed for 2 weeks to either pure MC-LR (100 μg/L) or Microcystisaeruginosa crude extracts containing 100 μg/L MC-LR. Chlorophyll fluorescence wasmeasured, leaf proteome investigated with two-dimensional gel electrophoresis and Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF)/TOF, andtoxin bioaccumulation assessed by liquid chromatography-mass spectrometry (LC-MS)/MS.Variations in several protein markers (ATP synthase subunits, Cytochrome b6-f complexiron-sulfur, oxygen-evolving enhancer proteins) highlight the decrease of the capacity ofplants to synthesize ATP and to perform photosynthesis, whereas variations in other proteins(ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit and ribose-5-phosphateisomerase) suggest an increase of carbon fixation and decrease of carbohydrate metabolismreactions in plants exposed to pure MC-LR and cyanobacterial extracts, respectively. MC-LRwas found in roots (1635.21 μg/kg fw), green tomatoes (5.15–5.41 μg/kg fw), maturetomatoes (10.52–10.83 μg/kg fw), and leaves (12,298.18 μg/kg fw). The results raiseconcerns relative to food safety and point to the necessity of monitoring the bioaccumulationof water toxins in agricultural systems affected by cyanotoxin contamination