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Taxonomy of the genus Quercus L. is very complicated and often controversial because of its great variability and intense gene flow among the related species. The purpose of this research was to determine morphological and molecular variation, relationships and taxonomic status of the Croatian populations of Quercus pubescens Willd. using morphological analysis of the leaves and RAPD-PCR technique. The results of the morphological and molecular analyses were very similar, both showing differentiation of the southern (Mediterranean) from the northern (Continental) pubescent oak populations. These two groups were clearly separated and the estimated gene flow among the populations that belong to different groups (Nm=1.38) is significantly less than among the populations that belong to the same group (Nm=3.70). The obtained results were compared to the available studies. This study confirms a high variability of the Q. pubescens populations, but differences were not so big to confirm the opinion of existence of several species in this area. The conclusion is that the southern Croatian populations could be pure Q. pubescens populations, while the peculiarities of the northern Croatian populations originate probably from the Q. petraea introgression.
The study involved screening and SEM analysis of the micromorphological features of the abaxial leaf surface of ordinary epidermal cells, stomata and trichomes of two varieties of Quercus cerris L. The results indicated features distinguishing the two varieties: in var. austriaca the wax is present as crystalloids in the form of simple platelets, while in var. cerris the wax appears as a smooth layer. Moreover, the results point to some special characteristics of Q. cerris in relation to other Quercus species. The approximately square, not ellipsoid, shape of the peristomatal rims is typical of the species Q. cerris L.
This study investigated cross-reactivity between allergens of Cupressaceae and Fagaceae pollen. Human IgE raised against Cupressus arizonica pollen allergen was used to demonstrate the presence of related allergens on ultrathin sections of Fagaceae pollen (Quercus ilex, Castanea sativa, Fagus sylvatica). Tissue localization of the cross-reactive allergen was investigated by immunogold electron microscopy. TEM observations showed that IgE raised against C. arizonica allergen recognizes epitopes on Fagaceae pollen. The cross-reactive allergens can be found on the wall and in the cytoplasm.
The abaxial epidermis of pubescent oaks, Quercus brachyphylla Kotschy, Quercus dalmatica Radić and Quercus pubescens Willd., was studied with the Scanning Electron Microscope. Micro-morphological features (surface of trichomes, stomata, ordinary epidermal cells and wax) do not permit to distinguish the three oaks species. Nevertheless, the difference among the taxa exist in leaf phenology and time of appearance and rate of degradation of epicuticular wax crystalloids. Alteration of wax crystalloids into amorphous wax is interpreted in favour of natural phenomenon of the wax ageing and degradation.
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