Flowering Phenology and Characteristics of Pollen Aeroparticles of Quercus Species in Korea

In recent decades, airborne allergens for allergic respiratory diseases have been found to increase significantly by a process of converting coniferous forests into broad-leaved forests in Korea. This study was conducted to evaluate factors, including airborne pollen counts, micromorphology, and flowering phenology, that can affect oak pollen-related allergic symptoms. The catkin of Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) showed the most rapidly blooming catkin on Julian day 104 in flower development. Among six species, the last flowering was observed on Julian day 119 in Korean oak (Quercus dentata Thunb.). The pollen dispersal was persisted for about 32 days from Julian day 104 to Julian day 136. Airborne pollen was observed about 2 weeks after flowering phase H, the senescence phase. Pollen size varied by species, with the largest from Q. mongolica (polar axis length, PL = 31.72 µm, equatorial axis length, EL = 39.05 µm) and the smallest from Jolcham oak (Quercus serrata Murray) (PL = 26.47 µm, EL = 32.32 µm). Regarding pollen wall structure, endexine of Q. dentata was coarsely laminated or fragmented. The endexine thicknesses of Sawtooth oak (Quercus acutissima Carruth.) and Q. serrata were thick and stable, whereas Galcham oak (Quercus aliena Blume), Q. mongolica, and Oriental cork oak (Quercus variabilis Blume) had thinner endexines. The area occupied by pollenkitt of Q. variabilis was significantly larger than that of Q. acutissima. Importantly, Q. variabilis had a distinctly thick 17 kDa protein band, a presumed major allergen. Oak species differ in pollen protein composition, and thus there is a possibility that the allergenic activity of pollen proteins vary depending on oak species. This study highlights the fact that native oak species in Korea differ in flowering pattern of male flowers, pollen morphology, and pollen chemical constituents. These discrepancies in flowering and pollen properties imply variable allergic responses to oak pollen from different species

Surface-Based Analysis of Leaf Microstructures for Adsorbing and Retaining Capability of Airborne Particulate Matter in Ten Woody Species

We evaluated surface-based analysis for assessing the possible relationship between the microstructural properties and particulate matter (i.e., two size fractions of PM2.5 and PM10) adsorption efficiencies of their leaf surfaces on ten woody species. We focused on the effect of PM adsorption capacity between micro-morphological features on leaf surfaces using a scanning electron microscope and a non-contact surface profiler as an example. The species with higher adsorption of PM10 on leaf surfaces were Korean boxwood (Buxus koreana Nakai ex Chung & al.) and evergreen spindle (Euonymus japonicus Thunb.), followed by yulan magnolia (Magnolia denudata Desr.), Japanese yew (Taxus cuspidata Siebold & Zucc.), Japanese horse chestnut (Aesculus turbinata Blume), retusa fringetree (Chionanthus retusus Lindl. & Paxton), maidenhair tree (Ginkgo biloba L.), and royal azalea (Rhododendron schlippenbachii Maxim.). There was a higher capacity for the adsorption of PM2.5 on the leaf surfaces of B. koreana and T. cuspidata, followed by A. turbinata, C. retusus, E. japonicus, G. biloba, and M. denudata. In wax layer tests, T. cuspidata, A. turbinata, R. schlippenbachii, and C. retusus showed a statistically higher PM2.5 capturing capacity than the other species. Different types of trichomes were distributed on the adaxial and abaxial leaves of A. turbinata, C. retusus, M. denudata, pagoda tree (Styphnolobium japonicum (L.) Schott), B. koreana, and R. schlippenbachii; however, these trichomes were absent on both sides of the leaves of G. biloba, tuliptree (Liriodendron tulipifera L.), E. japonicus, and T. cuspidata. Importantly, leaf surfaces of G. biloba and S. japonicum with dense or thick epicuticular leaf waxes and deeper roughness revealed lower PM adsorption. Based on the overall performance of airborne PM capture efficiency, evergreen species such as B. koreana, T. cuspidata, and E. japonicus showed the best results, whereas S. japonicum and L. tulipifera had the lowest capture. In particular, evergreen shrub species showed higher PM2.5 depositions inside the inner wall of stomata or the periphery of guard cells. Therefore, in leaf microstructural factors, stomatal size may be related to notably high PM2.5 holding capacities on leaf surfaces, but stomatal density, trichome density, and roughness had a limited effect on PM adsorption. Finally, our findings indicate that surface-based microstructures are necessarily not a correlation for corresponding estimates with leaf PM adsorption

Plant diversity in different bioclimatic zones in Tunisia

The Republic of Tunisia, located in northern Africa, faces various environmental challenges caused by anthropogenic practices such as overgrazing, deforestation, and desertification. The conversion of natural ecosystems is the major cause of plant biodiversity loss. Tunisia can be divided into three main climatic zones as follows: a northern Mediterranean climate zone, a central steppe climate zone, and a southern desert climate zone. Because of this great environmental diversity, there are distinctive vegetation and various genetic resources in Tunisia. This research was conducted to investigate plant biodiversity within the various bioclimatic zones and to characterize useful plant resources in Tunisia. We investigated native, medicinal and aromatic, desert, and soil erosion control plant species