Identification and Characterization of Nectria pseudotrichia Associated with Camellia Canker Disease in China

Camellia japonica is a native tree species with high economic value that is widely cultivated in southern China. In recent years, canker disease has been observed in camellia plantations in Zhejiang Province, China, with the disease incidence rate in some plantations exceeding 20%. Canker disease severely affects the trunks and branches of C. japonica in China, but the causal agent has not yet been identified. In this study, the pathogen was isolated from infected C. japonica tissues through a conventional tissue isolation approach. Species identification was conducted using morphological methods combined with multilocus phylogenetic analysis. Pathogenicity was tested based on Koch’s postulates. The results showed that the pathogen could be isolated from the diseased bark of C. japonica ‘Hongluzhen’. The pathogen was identified as Nectria pseudotrichia based on morphological, cultural, and molecular traits. The inoculation of the pathogen into C. japonica ‘Hongluzhen’ caused necrotic lesions on healthy seedlings, and the fungus N. pseudotrichia could be re-isolated from such lesions. Therefore, N. pseudotrichia is the causal agent of canker disease affecting C. japonica in China.

Camellia japonica Essential Oil Inhibits α-MSH-Induced Melanin Production and Tyrosinase Activity in B16F10 Melanoma Cells

Essential oils are aromatic oils extracted from the leaves, stems, peels, petals, and roots of aromatic plants grown in nature or grown in organic methods and have various medical effects as natural substances. The essential oil extracted from Camellia japonica seeds exhibits various functional properties; however, its tyrosinase inhibitory activity has not been investigated extensively. This study is performed to investigate the chemical composition and tyrosinase inhibitory activity of Camellia japonica seed essential oil (CJS-EO). Hexamethylcyclotrisiloxane (42.36%) and octamethylcyclotetrasiloxane (23.28%) are the two primary components of CJS-EO, as identified via gas chromatography-mass spectrometry. The inhibitory activities of CJS-EO and positive control arbutin are further evaluated against mushroom tyrosinase. The results show that CJS-EO and arbutin inhibit tyrosinase activity. Moreover, CJS-EO significantly inhibits melanogenesis in the α-melanocyte-stimulating hormone-treated group, and a significant amount of melanin is suppressed. To ascertain the cause of the CJS-EO tyrosinase inhibitory effect and melanin reduction effect, genetic and protein analyses are performed. Based on our results, we tentatively conclude that CJS-EO can inhibit melanocytes from harmful factors such as tyrosinase-related protein. These results demonstrate that CJS-EO possesses potent antityrosinase activity and may be a good skin-whitening agent.

Anticancer properties of dried-pericarp water extracts of Camellia japonica L. fermented with Aspergillus oryzae through regulation of IGFBP-2/mTOR pathway

This study aimed to investigate the anticancer activity of dried-pericarp water extract of fermented C. japonicus (CJ). The dried-pericarp water extracts of CJ were fermented using Aspergillus oryzae and Saccharomyces cerevisiae at 30 °C and 35 °C. The anticancer activities of both water extracts fermented at 30 °C and 35 °C using A. oryzae against FaDu cells were remarkably changed compared with unfermented dried-pericarp water extract of CJ, which has no anticancer activity. Cleaved-PARP, caspase 3, and apoptotic cells stained with annexin V/PI were significantly increased by treatment with A. oryzae extracts fermented at 30 °C. The insulin-like growth factor-binding protein 2 (IGFBP-2) protein level and mTOR phosphorylation by A. oryzae fermented extracts (AOFE) were dramatically reduced, and the expression levels of IGFBP-2 and phosphorylated mTOR were significantly increased depending on the glucose concentrations in FaDu cells. These results suggested that the cell viabilities in AOFE were restored as the glucose concentrations increased. Furthermore, it was confirmed LC/MS/MS that the content of gallic acid was increased by fermentation of Aspergillus oryzae (5.596 ± 0.1746 μg/mg) compared to the unfermented extract (1.620 ± 0.0432 μg/mg). Based on these results, the anticancer effect of AOFE was achieved through inhibition of the IGFBP-2/mTOR signaling pathway. These results suggest that AOFE may be a potential treatment for head and neck cancer.

Analysis of variability of morphological characteristics of Japanese camellia varieties (Camellia japonica L.) In the conditions of protected ground of the city Moscow

In the present work, the analysis of the variability of quantitative and qualitative morphological traits of Japanese Camellia (Camellia japonica L.) varieties used in greenhouses of botanical institutions in Moscow is considered. The paper considers the following varieties: ‘Governor Mouton’, ‘Madame Lebois’, ‘Covina’, ‘Bella Toscana’, ‘Bonomiana’, ‘Alba Simplex’, ‘Lavinia Maggi’, ‘ Silver Waves ’,‘ Doncklaeri ’. To assess the variability, 10 characters were selected, six of which describe the leaf (leaf blade length, leaf blade width, leaf ovality index, leaf blade base shape, leaf blade apex shape, leaf blade shape) and four – flowers (corolla color, flower diameter, degree of terry and aroma). The variability of quantitative characteristics was assessed by determining the confidence intervals method and calculating the coefficients of variation. The variability of qualitative features was assessed by establishing modalities and determining modes. It is noted that, in terms of quantitative and qualitative characteristics, weak variability is observed in most cases. Thus, the studied varieties of Japanese camellia have stable features that characterize the flower and leaf blade. Keywords: CAMELLIA JAPONICA, JAPANESE CAMELLIA, VARIABILITY, VARIETIES

Genetic Variation and Phylogeny of Wabisuke Camellias by Amplified Fragment Length Polymorphism (AFLP) Analysis

Amplified fragment length polymorphism (AFLP) analysis was conducted on the wabisuke camellia and its relative camellia species. Genetic polymorphism was identified among the ‘Uraku’ camellia, its offspring ‘Tosa-uraku’ and Camellia japonica, whereas the two accessions of the old ‘Uraku’ showed monomorphism in all the fragments. The results suggested that the two old ‘Uraku’ trees are asexually-propagated clonal strains. The genetic distance between wabisuke cultivars and Chinese camellias and between wabisuke camellias and C. sinensis was much further than that between wabisuke cultivars and Camellia japonica. It has also been suggested that wabisuke camellias can be classified into two subgroups, I-1 and I-2, and that Subgroup I-2 originated from C. japonica, while Subgroup I-1, including ‘Uraku’ (synonym: ‘Tarokaja’), was developed by the repeated hybridization of C. japonica to interspecific hybrids with the Chinese camellias, e.g., C. pitardii var. pitardii, or by the involvement of related species not investigated in this study.

Comparative transcriptome and microbial community sequencing provide insight into yellow-leaf phenotype of Camellia japonica

Background Leaf color variation is a common trait in plants and widely distributed in many plants. In this study, a leaf color mutation in Camellia japonica (cultivar named as Maguxianzi, M) was used as material, and the mechanism of leaf color variation was revealed by physiological, cytological, transcriptome and microbiome analyses. Results The yellowing C. japonica (M) exhibits lower pigment content than its parent (cultivar named as Huafurong, H), especially chlorophyll (Chl) and carotenoid, and leaves of M have weaker photosynthesis. Subsequently, the results of transmission electron microscopy(TEM) exhibited that M chloroplast was accompanied by broken thylakoid membrane, degraded thylakoid grana, and filled with many vesicles. Furthermore, comparative transcriptome sequencing identified 3,298 differentially expressed genes (DEGs). KEGG annotation analysis results showed that 69 significantly enriched DEGs were involved in Chl biosynthesis, carotenoid biosynthesis, photosynthesis, and plant-pathogen interaction. On this basis, we sequenced the microbial diversity of the H and M leaves. The sequencing results suggested that the abundance of Didymella in the M leaves was significantly higher than that in the H leaves, which meant that M leaves might be infected by Didymella. Conclusions Therefore, we speculated that Didymella infected M leaves while reduced Chl and carotenoid content by damaging chloroplast structures, and altered the intensity of photosynthesis, thereby causing the leaf yellowing phenomenon of C. japonica (M). This research will provide new insights into the leaf color variation mechanism and lay a theoretical foundation for plant breeding and molecular markers.

CBF transcription factors involved in the cold response of Camellia japonica (Naidong)

CBFs belong to the ERF subfamily of the AP2 supergene family and often play an important role in the cold acclimation of temperate plants. However, the role of CBFs in Camellia japonica (Naidong), the only Camellia japonica population found in the temperate zones of China, remains unclear. It is very important to study the genetic composition of C. japonica (Naidong) to adapt to low temperature for Camellia species. Using full-length transcriptome data, we identified four CjCBF genes that respond to cold stress and analyzed their evolutionary relationships, domains, and expression patterns. The phylogeny of CBFs of 19 angiosperms divided the genes into three categories, and the four CjCBFs belong to a small subcluster. The strong response of CjCBF1 to cold treatment and its sustained high level of expression indicated that it plays an important role in the process of cold acclimation. A yeast two-hybrid assay revealed an interaction between CjCBF1, CjCBF2, and CjCBF5, and subcellular localization confirmed this finding. The expression of CjCBFs was tissue-specific: CBF1 was mainly expressed in leaves, and CBF3 was mainly expressed in stem. The responses of the four CjCBFs to drought and high temperature and the effect of light were also characterized. Our study provides new insight into the role of CBFs in the cold response in C. japonica (Naidong).