Scientists' Contributions

Particulate Matter Effect on Petunia"Blue Spark" Plants

R. Lobel, Y. Mamane, S. Gepstein and A. Borochov

    Though particulate matter is a major pollutant, there is little information of flora response to it. This work examines particulate matter effects on plants.

    At first we screened a heavily polluted area near a quarry. Electron microscopy analysis results carbonate makeup particles (sizes ranged from 0.1 to more then 50 with a random accumulation on the surface of leaves. The next phase was laboratory simulation. Rose and Petunia plants were exposed to the similar mineral particles. The plants showed significant deceleration in their growth rate. No changes in number of leaves, number of elongating lateral buds, and number of flowers were detected. The changes were noticeable after two weeks. These changes are similar to morphological changes after mechanical stimulation (like touching and wind) which are involved in tigmomorphogenesis process. In the laboratory simulation light transmitted through the particles layer was similar to the sunlight spectrum, yet, blue light had a slightly better transmittance. Although blue light is essential in plants growth, it is probably not the main reason for the observed changes. Two physiological systems, the photosynthesis system and the cell membranes, that are known to be sensitive to environmental changes showed no changes as a result of the different treatments. In the third phase, molecular indicators for changes in gene expression were examined. A DNA fragment, dig, was isolated, and had shown similarity to gene family, TCH, which involved in plants response to mechanical stimulation. Increase in mRNA levels were detected short after dust or mechanical stimuli, in stems and l eaves tissues. The levels decline to the normal rate at later occasions.

    It was concluded that exposure of plants to particulate matter can function as mechanical stimuli leading to short phenotype.