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  • Author or Editor: Maria Drapikowska x
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Tropospheric ozone causes visible injuries in selected plants. Some plant species have been recognized as resistant and sensitive to ozone. Differences in the response to ozone of two kinds of plants are interesting because of practical implications. Resistant cultivars (without visible symptoms) will be more valuable for agriculture, forestry and horticulture. It is, however, necessary to find out the reason of the occurrence of the visible symptoms. The presented studies focused on selected morphological and anatomical differences between well-known ozone-sensitive (Bel W3) and -resistant (Bel B) cultivars of tobacco plants. Daily growth of the sensitive cultivar was higher than that of the resistant one. This tendency was also valid for the leaf growth which might have been the response of the sensitive cultivar to decreased photosynthetic leaf area (necrosis) caused by ozone. Morphological investigations revealed thinner upper epidermal cells in the sensitive cultivar. Moreover, a decrease of spongy mesophyll cell layers was observed. The obtained results suggest that it is the anatomical structure that may be partly responsible for ozone resistance — wider epidermal cells, more spongy mesophyll cell layers.

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Diploid Anthoxanthum odoratum and tetraploid A. aristatum were compared with respect to stomatal guard cell lengths, and stomatal density at adaxial and abaxial surfaces of the lamina. Further, the genome size of both species was determined by flow cytometry, and the number as well as the chromosomal distribution of 5S and 45S rDNAs were examined using FISH with ribosomal DNA (rDNA) probes. The average length of stomatal guard cells in A. odoratum was shown to be greater than that for A. aristatum, but the ranges overlapped. Moreover, reduction in stomatal frequency was found at higher ploidy levels.The genome size was 6.863 pg/2C DNA for A. aristatum and 13.252 pg/2C DNA for A. odoratum. A. aristatum has four sites of 5S rDNA in its root-tip meristematic cells, whereas A. odoratum has six. Both species have six sites of 45S rDNA. Chromosomal localization of the rDNA varied, which suggests that chromosome rearrangements took place during Anthoxanthum genome evolution.

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