Crystal occurrence and wax disruption on leaf surfaces of cabbage treated with simulated acid rain

Abstract

S U M M A H VEpicuticular waxes on leaves of Brassica olercuea L. (cabbage) were studied using scanning electron microscopy after a single treatment with simulated rain of pH 5-6, 3-0 or 2-5 which was either sprayed on to plants in an exposure chamber or applied as droplets with a micropipette. Treatments with acidified rain caused serious structural degradation of the wax crystals. The alteration of crystalline wax structures was similar for leaves treated with nitric acid solutions, but less se\-ere, than for leaves treated with sulphuric acid solutions. With both H.,SO| and HNOj-derived rain solutions numerous gypsum (CaSO,,) crystals were found in and near lesions on the leaves treated with rain of pH 3-0 and 2-5. The crystals probably resulted from damage of cuticular membranes by acidic rain which significantly altered their permeability to ions in the area of lesions. Crystalline leaf waxes may be an important target for acidic pollutants, and the physiological consequences of their degradation are discussed.

Modifications in the alkane composition of cuticular waxes from spruce needles (Picea abies) and ivy leaves (Hedera helix) exposed to ozone fumigation and acid fog: comparison with needles from declining spruce trees

“…Waxes flatten, thicken, and agglomerate till they become amorphous (Turunen and Huttunen 1990;Grill et al 1987). This structural degradation has also been mentioned in the case of simulated pollutions, e.g., acid rain (Schmitt et al 1987;Adams et al 1990), acid fog (Lutz et al 1990;Percy et al 1990), ozone (Percy et al 1990), and sulfur dioxide (Schmitt et al 1987) fumigations. However, similar alterations have been observed on healthy tree foliage during ageing (Sauter and Voss 1986;Horntvedt 1988).…”

Análise estrutural de folhas de Eugenia uniflora L. (Myrtaceae) coletadas em ambientes rural e urbano, SP, Brasil

“…Segundo Franceschi & Horner (1980) a síntese de oxalatos está relacionada com o balanço iônico da planta, portanto os cristais, que na sua maioria são compostos de oxalato de cálcio, representam uma estratégia da planta para manter o equilíbrio iônico que é afetado quando a carga de poluentes é elevada. O aumento na quantidade de cristais é uma resposta que vem sendo observada em diferentes plantas submetidas a poluentes gasosos e chuva ácida (Adams et al 1990;Fink 1991). Poluentes gasosos, como o ozônio, aumentam a permeabilidade das membranas celulares, promovendo um influxo de Ca ++ do apoplasto para o interior das células.…”

Plants as sources of cations antagonistic to glyphosate activity

“…In other experiments with this latter species, crystals of calcium sulphate have been observed in the foliar lesions arising from the neutralisation of acid rain. These crystals were formed as a result of the interaction of calcium leached from the plant with sulphuric acid present in acid rain or sulphur derived from within the plant tissue 28…”

“…Additional calcium could also arise from the chalk glands of A theophrasti . Commercial glyphosate products are usually acidic and sometimes contain surfactants that can penetrate the leaf cuticle, so this combination of properties could promote the foliar leaching of cations such as calcium, which are known to be present within the underlying cuticle and cell wall 27–29…”