High frequency (900 MHz) low amplitude (5 V m-¹) electromagnetic field: a genuine environmental stimulus that affects transcription, translation, calcium and energy charge in tomato

• Published in: Planta 2008-03, Vol.227 (4), p.883-891
• Main Authors: Roux, David, Vian, Alain, Girard, Sébastien, Bonnet, Pierre, Paladian, Françoise, Davies, Eric, Ledoigt, Gérard
• Format: Article
• Language: English
• Subjects: Accumulation; Agriculture; Biological and medical sciences; Biomedical and Life Sciences; Bonnets; Calcium; Calcium - metabolism; Chelating agents; Ecology; Electromagnetic Fields; Electromagnetism; Environmental stress; Forestry; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; Life Sciences; Lycopersicon esculentum - genetics; Lycopersicon esculentum - metabolism; Lycopersicon esculentum - radiation effects; Messenger RNA; Metabolism; Original Article; Photosynthesis, respiration. Anabolism, catabolism; Plant cells; Plant physiology and development; Plant Sciences; Polyribosomes; Protease inhibitors; Protein Biosynthesis - radiation effects; Proteinase inhibitors; Reverse Transcriptase Polymerase Chain Reaction; RNA; Roux; Tomatoes; Transcription, Genetic - radiation effects; Vegetal Biology
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-007-0664-2

Using an especially-designed facility, the Mode Stirred Reverberation Chamber, we exposed tomato plants (Lycopersicon esculentum Mill. VFN8) to low level (900 MHz, 5 V m-¹) electromagnetic fields for a short period (10 min) and measured changes in abundance of three specific mRNA soon after exposure. Within minutes of electromagnetic stimulation, stress-related mRNA (calmodulin, calcium-dependent protein kinase and proteinase inhibitor) accumulated in a rapid, large and 3-phase manner typical of an environmental stress response. Accumulation of these transcripts into the polysomal RNA also took place (indicating that the encoded proteins were translated) but was delayed (indicating that newly-synthesized mRNA was not immediately recruited into polysomes). Transcript accumulation was maximal at normal Ca²⁺ levels and was depressed at higher Ca²⁺, especially for those encoding calcium-binding proteins. Removal of Ca²⁺ (by addition of chelating agents or Ca²⁺ channel blocker) led to total suppression of mRNA accumulation. Finally, 30 min after the electromagnetic treatment, ATP concentration and adenylate energy charge were transiently decreased, while transcript accumulation was totally prevented by application of the uncoupling reagent, CCCP. These responses occur very soon after exposure, strongly suggesting that they are the direct consequence of application of radio-frequency fields and their similarities to wound responses strongly suggests that this radiation is perceived by plants as an injurious stimulus.