chlorophyll-a and methyl-tert-butyl-ether

The current investigation was conducted to report on the phytotoxicity of methyl tert-butyl ether (MTBE) to common bean (Phaseolus vulgaris L. cv. Nebraska) plants. The two-week-old potted plants were subjected to four weekly soil applications of aqueous MTBE concentrations (0, 1, 10, 25 and 50 ml L(-1)). The root growth, flower and pod development were more sensitive to MTBE treatments; while, stem growth and photosynthetic pigments were more persistent to the toxicity of MTBE. The total number of protein bands/lane in SDS-PAGE protein profile was reduced by MTBE treatments. Two proteins of molecular weight 53.83 and 30.96 kDa were newly synthesized at the highest concentrations (25 and 50 ml L(-1)) of MTBE; while the syntheses of other proteins were completely inhibited with varying sensitivity to MTBE concentrations. The toxicity of MTBE concentrations caused progressive collapsing of epidermal and cortical tissues of the plant roots. MTBE is quite toxic to crop plants in contaminated soils of agricultural systems.

Topics: Agriculture; Air Pollutants; Chlorophyll; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Flowers; Methyl Ethers; Molecular Weight; Phaseolus; Photosynthesis; Pigmentation; Plant Physiological Phenomena; Plant Roots; Soil; Toxicity Tests

A selection of herbaceous plants representing the ground flora around a typical chemical installation in the UK was exposed continuously for 7 weeks to a mixture of six VOCs (acetone, acetonitrile, dichloromethane, ethanol, methyl t-butyl ether and toluene) in open-top chambers. Exposure concentrations were based on predictions of atmospheric dispersion from a single source, at a distance of approximately 2 km. The effects of continuous exposure, representing a worst-case, were measured in terms of uncontrolled water loss from leaves, leaf wettability, chlorophyll content and fluorescence, dry matter production and detailed observations of changes in plant growth and phenology. There were significant effects of VOC exposure on seed production, leaf water content and photosynthetic efficiency in some plant species. Such effects may be detectable in vegetation close to major industrial point sources of VOCs, or as a result of an accidental release of material during manufacture or transport. Some of the species tested e.g. birdsfoot trefoil (Lotus corniculatus L.) seem to be promising as potential bioindicators for VOCs, but there may be other even more sensitive species waiting to be discovered. However, the most obvious and conveniently measured response to VOCexposure in the birdsfoot trefoil (premature senescence i.e. advanced timing of seed pod production) could easily be confused in the field with climatic influences. It is also uncertain at this stage whether any of the effects observed would lead to longer term ecological changes in natural plant communities, through biased competition between sensitive and more tolerant species.

Topics: Acetone; Acetonitriles; Air Pollutants; Chlorophyll; Environmental Monitoring; Ethanol; Flowers; Hydrocarbons, Aromatic; Methyl Ethers; Methylene Chloride; Plant Development; Plant Leaves; Plants; Toluene