Pajtík J., Konôpka B., Bošela M., Šeben V., Kaštier P., 2014. Modelling forage potential for red deer: a case study in post-disturbance young stands of rowan. Ann. For. Res. 58(1): 91-107.Abstract. Recently, the red deer (Cervus elaphus) population has increased considerably and caused serious damage in forest stands in Slovakia as well as in other Central-European countries. Rowan (Sorbus aucuparia L.) is the tree species that is most intensively browsed and stripped by deer, especially during young stages of tree development. Our research focuses on estimating rowan mass consumption by red deer in young stands which developed after large-scale wind disturbance that occurred in the Tatra National Park in 2004. New models were developed for estimating the mass of tree components that are potentially edible by red deer using tree-base diameter as an independent variable. The results showed that the mass contribution of particular tree components to accessible deer forage depended on tree size (tree-base diameter). At stand level, total forage potential increased with an increase in tree size. However, whereas the quantity of bark available for stripping increased with tree size, the total mass accessible for browsing (leader shoot and branches with foliage) decreased. For instance, the contribution of stem bark to total forage potential in stands with a mean tree-base diameter of 20 mm and 50 mm was 15% and 50%, respectively. Theoretically, if all tree mass potential is consumed by red deer, young rowan stands (considering tree coverage of 50%) growing within an area of 100 m 2 might provide sufficient forage for one adult deer for ca. 10 days. It is suggested that rowan species should not be removed from forest stands in territories with a high deer population in order to decrease the potential damage of other, commercially important, tree species.

Although cytoskeleton is a driving force for cell division and growth in higher plants, there is little evidence about its components in parasitic angiosperms. Microtubules and actin filaments in cells of shoot apical meristem and root-like structure of stem holoparasites European (C. europaea L.) and Eastern (C. monogyna Vahl.) dodders, as well as in prehaustorium, the specific organ adapted to parasitism, were visualized for the first time by immunolabeling and fluorescence microscopy. The significance of cytoskeletal elements during germination and prehaustorium formation was addressed by treatments with taxol, oryzalin, latrunculin B, cytochalasin B/D, jasplakinolide, and 2,3-butanedione monoxime. In shoot apical meristem many dividing cells were observed, in contrast to root-like structure, devoid of cell divisions. Cortical microtubules were oriented transversely and/or obliquely, while actin filaments were randomly distributed in cells of both organs. Furthermore, longitudinal cortical microtubules were present in digitate cells of prehaustorium, and transverse arrays were found in its file cells. Long and short random actin filaments were also observed in prehaustorium cells. Thus, it was shown that the cytoskeleton in dodder shoot cells is organized in a similar way to non-parasitic dicots, while cytoskeletal organization has some peculiarities in quickly senescing root-like structure and prehaustorium.

Dodder (Cuscuta) species cause severe agricultural damage in many countries throughout the world. To establish strategies for control of its growth and spreading it is important to study its life cycle and survival strategies. For these efforts genetic modification would represent a powerful tool. Here we report on Agrobacteriummediated transformation of dodder using green fluorescent protein (GFP) fused to actin-binding protein as a vital marker. Since the shoot of germinating C. europaea contains a functional apical meristem and grows quickly comparing to the root-like structure, the shoot apex was used here as explant. The transgene expression was only transient, nevertheless it enabled to detect allocation of actin filaments and studying the cytoskeleton organization in dodder shoot apex. Transient expression of GFP appears to be a suitable method for studying Cuscuta development through cytoskeleton organisation that is presently largely unexplored.

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