Similarities and differences in the microbial structure of surface soils of different vegetation types.

Background: Soil microbial community diversity serves as a highly sensitive indicator for assessing the response of terrestrial ecosystems to various changes, and it holds significant ecological relevance in terms of indicating ecological alterations. At the global scale, vegetation type acts as a major driving force behind the diversity of soil microbial communities, encompassing both bacterial and fungal components. Modifications in vegetation type not only induce transformations in the visual appearance of land, but also influence the soil ecosystem's material cycle and energy flow, resulting in substantial impacts on the composition and performance of soil microbes. Methods: In order to examine the disparities in the structure and diversity of soil microbial communities across distinct vegetation types, we opted to utilize sample plots representing four specific vegetation types. These included a woodland with the dominant tree species Drypetes perreticulata, a woodland with the dominant tree species Horsfieldia hainanensis, a Zea mays farmland and a Citrus reticulata fields. Through the application of high-throughput sequencing, the 16S V3_V4 region of soil bacteria and the ITS region of fungi were sequenced in this experiment. Subsequently, a comparative analysis was conducted to explore and assess the structure and dissimilarities of soil bacterial and fungal communities of the four vegetation types were analyzed comparatively. Results: Our findings indicated that woodland soil exhibit a higher richness of microbial diversity compared to farmland soils. There were significant differences between woodland and farmland soil microbial community composition. However, all four dominant phyla of soil fungi were Ascomycota across the four vegetation types, but the bacterial dominant phyla were different in the two-farmland soil microbial communities with the highest similarity. Furthermore, we established a significant correlation between the nutrient content of different vegetation types and the relative abundance of soil microorganisms at both phyla and genus levels. This experiment serves as a crucial step towards unraveling the intricate relationships between plants, soil microbes, and soil, as well as understanding the underlying driving mechanism.

Ursane-Type Triterpenes with a Phenylpropanoid Unit from Camellia ptilosperma and Evaluation of Their Cytotoxic Activities.

Six new ursane-type triterpenes with a phenylpropanoid unit and five known oleanane-type triterpenes were isolated from the leaves of Camellia ptilosperma. The undescribed compounds were identified by analysis of 1D and 2D NMR and HRESIMS spectroscopic data as ptilospermanols A-F. The cytotoxicity of new compounds against six human cancer cell lines and three mouse tumor cell lines was evaluated by MTT assay.

Characterization of the complete chloroplast genome of Carallia diplopetala (Rhizophoraceae).

Carallia diplopetala (Rhizophoraceae) is an important economic tree species narrowly distributed endemic to East Asia. In this study, We generate the complete chloroplast genome of C. diplopetala using next-generation sequencing technology, which is 162,052 bp in size and consists of a large single copy (LSC) of 89,556 bp and a small single copy (SSC) of 18,814 bp, separated a pair of inverted repeats (IRb and IRa) of 26,841 bp. The overall GC content is 36.4%. A total of 130 genes are annotated, including 83 protein-coding genes, 37 tRNAs, eight rRNAs and two pseudogenes (ψycf1 and ψrps19). The phylogenetic analysis indicated that C. diplopetala and C. brachiate formed a monophyletic clade with strong support and then sister to Pellacalyx yunnanensis. The plastome of C. diplopetala will provide informative genomic resources for further conservation applications.

A new species of Leptobrachella Smith 1925 (Anura: Megophryidae) from Southern Guangxi, China.

We described a new species of the genus Leptobrachella from Southern Guangxi, China, based on morphological characteristics, molecular analyses and bioacoustics. This new species, Leptobrachella shiwandashanensis sp. nov., occurs in sympatry with Leptobrachella shangsiensis. However, phylogenetic analyses based on the mitochondrial 16S gene fragment revealed that the new species was clustered in a monophyletic group and a considerable genetic divergence existed between the new species and L. shangsiensis (p-distance: 7.9%) as well as its congeners (minimum p-distance: 7.0%). The new species also differed from its congeners by a combination of the following characteristics: (1) small size (SVL 26.829.7 mm in males; 33.735.9 mm in females); (2) pale brown dorsal surfaces, with a brown inverse-triangle-shaped marking between the eyes; (3) creamy white ventral surface with brown spots on the lateral margin, with a near immaculate creamy white throat and chest; (4) without webbing and lateral fringes on toes; (5) flanks with irregular black spots; (6) tibia-tarsal articulation reaching the posterior of the eye in males but reaching the shoulder in females; (7) heels that do not meet when the thighs are appressed at right angles to the body; (8) bicolored iris, with the upper half brownish-red, fading to silver in the lower half; and (9) a call consisting of a single note and a dominant frequency of 5.35.7 kHz (recorded at 23C).

First Report of Anthracnose Caused by Colletotrichum siamense and C. fructicola of Camellia chrysantha in China.

Camellia chrysantha (Hu) Tuyama, belonging to the Theaceae family, is famous for its large size and golden yellow flowers, which has high ornamental and health care functions (Mo et al. 2013). Anthracnose is one of the most important fungal diseases worldwide, causing serious economic losses to many plants. In October 2019, severe anthracnose symptoms were observed on the leaves of C. chrysantha in a 0.6 hectare field with 15-20% disease incidence in Fangchenggang city, Guangxi Zhuang Autonomous Region of China. Diseased leaves initially appeared irregular chlorotic spots, which afterwards enlarged and coalesced. Finally, the spots became dark brown or black, sunken lesions (8-22 mm in diameter), and covered with plenty of acervuli. For pathogen isolation, the leaf lesions were cut into small tissue pieces (5 mm×5 mm), disinfected by 0.3% sodium hypochlorite for 2 min and 70% ethanol for 40 s, rinsed in sterile distilled water, and then incubated at 28°C on potato dextrose agar (PDA) plates. A total of 7 fungal isolates with whitish to light grey, dense colonies were recovered at 5 days. These isolates were tentatively identified as belonging to Colletotrichum gloeosporioides species complex through morphological and cultural characters (Weir et al. 2012). The conidia were nonseptate, cylindrical with obtuse to rounded ends, 13.9 to 18.3 (average 16.1) µm × 4.5 to 6.2 (average 5.4) µm (n = 50). For further precise identification, the 7 Colletotrichum isolates were analyzed using partial sequences of genomic loci including the internal transcribed spacer (ITS), ß-tubulin (TUB), calmodulin (CAL), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glutamine synthetase (GS), and the mating type locus MAT1-2 (ApMat) genes (Liu et al. 2015). The amplification sequences were compared with the sequences registered in the GenBank database based on nucleotide similarity. The above sequences of 4 isolates (JZB-PF4232, JZB-PF2231, JZB-PF42 and JZB-PF22) had 99-100% identity to the sequences of Colletotrichum siamense strains retrieved from GenBank, while the sequences of the other 3 isolates (JZB-PF3231, JZB-PF32 and JZB-PF41) showed over 99% identity with those of the C. fructicola strains. All the sequences were deposited in GenBank with accession number MT708987 to MT709007, MW149430 to MW149433, and MW142259 to MW142282. A multi-loci phylogenetic analysis of the concatenated sequences of ITS, TUB, CAL, ACT, GAPDH, GS and ApMat genes placed the 4 isolates described above in the C. siamense clade, while the other 3 isolates was attribute to the C. fructicola clade. Pathogenicity tests were conducted on 7 healthy 2-year-old C. chrysantha seedlings (cv. Fangpu), consisted of 21 wounded leaves made by a sterile needle, with 3 leaves per seedling. Artificial inoculations were performed by treating each seedling with 20 µl of spore suspension (106 conidia/ml) of each isolate. Leaves of seedlings treated with sterilized water under the same conditions served as controls. The experiment was repeated three times. All the seedlings were covered with plastic bags to maintain high humidity (90% RH) and placed in a greenhouse kept at 25°C with a 16 h light / 8 h dark photoperiod. After 8 days, the inoculated leaves of C. chrysantha plants developed typical dark brown or black lesions, similar to the symptoms in the field, whereas controls remained symptomless. Koch's postulates were fulfilled by re-isolation of the same fungi from symptomatic inoculated leaves, identification confirmed by morphological and molecular characteristics, respectively. C. siamense and C. fructicola have been found to cause anthracnose on Camellia sinensis (Wang et al. 2016; Shi et al. 2018). C. fructicola has also been reported to cause anthracnose on Citrus sinensis in China (Hu et al. 2019). To our knowledge, this is the first report of C. siamense and C. fructicola causing anthracnose on C. chrysantha in China.