Nanyan Liao

Phytochemical investigation of the leaves of Camellia flavida var. flavida led to the isolation of a previously undescribed acylated quercetin triglycoside (1), together with three known constituents (2–4). Their structures were established by HR-ESI-MS with 1D and 2D NMR analyses and, for the known compounds, by comparison with reported spectroscopic data. Compound 1 was elucidated as quercetin 3-O-[β-D-glucopyranosyl-(1→3)]-[α-L-rhamnopyranosyl-(1→6)]-[2-O-(E)-p-coumaroyl]-β-D-glucopyranoside. Compounds 1–3 inhibited lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages, with IC50 values of 14.9 ± 1.7, 13.4 ± 2.6, and 37.7 ± 2.9 μM, respectively, while their CC50 values were >64 μM. 4 was cytotoxic (CC50 10.9 ± 0.7 μM) and was therefore not evaluated for nitric oxide inhibition. These findings expand the known chemical diversity of C. flavida var. flavida and identify 1 and 2 as moderate inhibitors of nitric oxide production.

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 26.8–29.7 mm in males; 33.7–35.9 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 5.3–5.7 kHz (recorded at 23°C).

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), β-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.

Camellia chrysantha (Hu) Tuyama (golden camellia) is an important ornamental and medicinal plant grown in southern China, which is often referred to as “the queen of camellia” (Zhang et al. 2017). ...