Seasonal development of aboveground phytomass of evergreen introduced plants on the Southern Coast of the Crimea

For the Southern Coast of Crimea, the problem of park communities’ productivity, due to the high recreational load on the environment and climate change, is of particular relevance. The aim of the research was to study the features of the introduced park communities evergreen aboveground phytomass formation and seasonal growth in the conditions of the Southern coast of the Crimea. A comparative assessment of vegetative shoots seasonal growth features of plants Laurus nobilis L., Prunus laurocerasus L., Viburnum tinus L., Aucuba japonica Thunb and Nerium oleander L. was performed. It was found that the time of renewal of shoot growth in spring after winter dormancy in V. tinus and A. japonica began at 459-462 °C, P. laurocerasus - 649 °C, and L. nobilis - 886 °C and N. oleander - 990 °C amounts of active air temperatures above 5 °C. The largest growth (49.3 cm) and the accumulation of leaf phytomass (42.3 cm3) differ in annual shoots of N. oleander. P. laurocerasus has a great potential with a phytomass volume an annual shoot of 24.5 cm3. The increase of shoots phytomass in V. tinus, A. japonica, and L. nobilis is 7-8 times less than that in N. oleander.

Zn tolerance in the evergreen shrub, Aucuba japonica, naturally growing at a mine site: Cell wall immobilization, aucubin production, and Zn adsorption on fungal mycelia

Aucuba japonica Thunb. is an evergreen understory shrub that grows naturally at a mine site. The mine soil contains high concentrations of heavy metals, and A. japonica appears to maintain detoxification mechanisms against heavy metals in the study site’s understory. This study aimed to investigate the heavy metal tolerance mechanisms in A. japonica, considering the possible roles of arbuscular mycorrhizal and root-endophytic fungi. We conducted fieldwork in summer (canopy-foliation season) and winter (canopy-defoliation season) to measure the heavy metal concentrations in leaves, branches, and roots and analyze possible detoxicants in the roots. The infection rates of arbuscular mycorrhizal and root-endophytic fungi were evaluated via microscopic observation, and heavy metal (Zn) localization in A. japonica roots was observed using confocal laser scanning microscopy. Field analysis showed that A. japonica accumulated excessive Zn and produced aucubin and citric acid in the roots in both summer and winter. Zn localization observations clarified that Zn was distributed in thickened epidermal and cortical cell walls, suggesting that the cell walls functioned as Zn deposition sites, reducing Zn toxicity. It was further clarified that Zn was contained within cortical cells, indicating that Zn might be detoxified by aucubin and citric acid. Arbuscular mycorrhizal and root-endophytic fungi within cortical cells adsorbed Zn on fungal cell walls, indicating that these fungi would reduce Zn content within root cells and might alleviate Zn toxicity. Our results indicated that A. japonica would maintain Zn tolerance in both summer and winter via Zn immobilization in the cell walls and production of aucubin and citric acid, and that arbuscular mycorrhizal and root-endophytic fungi might play important roles in the Zn tolerance of A. japonica.

Comparative and Phylogenetic Analyses of Complete Plastomes of Aucuba (Garryaceae)

Backgroud: Aucuba (Garryaceae), which includes approximately 10 evergreen woody species, is a genus endemic to East Asia. Their striking morphological features give Aucuba species remarkable ornamental value. Owing to high levels of morphological divergence and plasticity, species definition of Aucuba remains perplexing and problematic. Here, we sequenced and characterized the complete plastid genomes (plastomes) of three Aucuba species: Aucuba chlorascens, Aucuba eriobotryifolia, and Aucuba japonica. Results: Comparative analyses revealed that Aucuba plastomes are highly conserved in size, structure, gene content, and organization, and exhibit high levels of sequence similarity. We recommend 11 plastid DNA regions as potential DNA barcodes for species identification and genotyping of Aucuba germplasm. Phylogenetic reconstruction based on 71 plastid protein-coding genes from taxa encompassing a wide phylogenetic diversity in the lamiids strongly supported the sister relationship between Garryaceae and Eucommiaceae. Conclusion: Plastome tree revealed the monophyly of Garryales, offering plastid phylogenomic evidence for the acceptance of Garryales as outlined by the updated Angiosperm Phylogeny Group. Under a comparative framework within Garryales, we detected massive plastome arrangements between Aucuba and Eucommia. In summary, our study provides useful genomic resources for further study of the taxonomy, evolution, conservation, and exploitation of Aucuba species.

A comparative assessment of C02/H20 gas exchange in evergreen woody and shrubby plants under favorable and stressful environmental conditions

A comparative assessment of the adaptive response of the photosynthetic apparatus and water regime in 6 evergreen tree and shrub plant species to the effect of abiotic factors and their strategies in supporting optimal water balance in accordance with environmental conditions was carried out. Parameters of photosynthesis light response curves under conditions of full sunlight and moderate shading were determined. It is shown that due to the low plasticity to changes in the light regime Arbutus andrachne L. may have a significant lack of light in strong shading. Important adaptive features of Laurus nobilis L., Aucuba japónica Thunb. and Viburnum tinus L. is the ability of the photosynthetic apparatus to effectively use low light and maintain a positive carbon balance in conditions of strong shading. Three types of plant response to water deficit have been identified. Drought- resistant type of water balance regulation by closing stomata is characteristic of Nerium oleander L. and Laurus nobilis. In Aucuba japónica and Prunus laurocerasus L. a reaction aimed at preserving the water balance in the plant by maintaining a high level of transpiration has been identified. The third type of plant response to water deficit which combines both types of reaction provides high adaptive ability to drought Viburnum tinus and Arbutus andrachne. Drought tolerance of Arbutus andrachne was the highest among the studied species.

Aucubin, An Active Ingredient in Aucuba japonica, Prevents N-methyl-N-nitrosourea-induced Retinal Degeneration in Mice

In the present study, we examined the potent retinoprotective effects of an ethanol-based extract of Aucuba japonica (AJE) and its active ingredient, aucubin, on N-methyl-N-nitrosourea (MNU)-induced retinal degeneration in mice. Retinal degeneration was induced by an intraperitoneal injection of MNU (60 mg/kg). AJE (250 mg/kg) and aucubin (15 mg/kg) were orally administered for 1 week after the MNU injection. Electroretinography (ERG) and histological examinations were performed. Retinal apoptosis and oxidative DNA damage were also quantified. The retinoprotective abilities of AJE and aucubin were also assessed in primary cultured retinal cells. Morphologically, MNU induced a remarkable decrease in the outer nuclear layer, which contains photoreceptor cells. However, this layer was well preserved in the AJE- and aucubin-administered mice. The ERG responses significantly decreased in both a- and b-wave amplitudes in the MNU-injected mice. In the AJE and aucubin-treated mice, ERG responses were significantly increased. In addition, a terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) assay and immunohistochemical staining for 8-hydroxydeoxyguanosine (8-OHdG) revealed that both AJE and aucubin attenuated MNU-induced photoreceptor cell apoptosis and oxidative DNA damage. Furthermore, the in vitro assay also showed that AJE and aucubin have potent anti-oxidative and anti-apoptotic activities in primary cultured retinal cells. These results indicate that AJE and aucubin have potent retinoprotective effects, and that this retinoprotective activity is as a result of the potency of the bioactive compound, aucubin. These pharmacological characteristics suggest the additional application of AJE or aucubin in the treatment of patients with retinal degenerative diseases.