First report of Corynespora cassiicola causing leaf spot on Nanhaia speciosa in China.

Nanhaia speciosa, commonly known as Niudali, is a medicinal woody vine belonging to the Leguminosae family. Valued for its culinary and medicinal properties, it is extensively cultivated, covering approximately 5,973 hm2 in the Guangxi Zhuang Autonomous Region of China. The edible tubers of this plant are reported to possess antibacterial and antioxidant effects (Luo et al., 2023; Shu et al., 2020). In July 2021, a Niudali plantation in Yulin, Guangxi, China (22°64'N; 110°29'E) exhibited leaf spot symptoms, with an incidence rate exceeding 40% across a 46,690 m2 area. Initially, small circular, pale yellow spots appeared on the leaves, which subsequently evolved into dark brown lesions surrounded by yellow halos, ultimately leading to foliage wilting. Leaves exhibiting typical symptoms were collected for pathogen investigation. The leaves were thoroughly washed with sterile water and small tissue fragments (5×5 mm) were excised from the lesion periphery. These fragments were surface-sterilized with 75% ethanol and 1% NaClO, rinsed three times with sterile water, and subsequently cultured on potato dextrose agar (PDA) at 28 °C in darkness for 7 days. Through single-spore isolation, seven isolates with similar morphological traits were obtained. After 7 days of incubation on PDA at 28 °C in dark, the colonies exhibited a white to grey coloration on the upper surface with abundant aerial hyphae, while the underside appeared dark black. The conidia, cylindrical or obclavate in shape, were straight, pale brown, and measured 30.1-128.9 µm × 4.8-15.0 µm (n=50). The morphological characteristics matched those of Corynespora sp.(Wang et al. 2021). For molecular identification, the isolate N5-2 underwent DNA sequence analysis using genomic DNA and primers ITS1/ITS4 and EF1-688F/EF1-1251R. The sequences (ITS: OP550425; TEF1-α: OQ117118) were deposited in GenBank, exhibiting 98% identity to C. cassiicola (OP981637) for TEF1-α and 99% homology to C. cassiicola (OP957070) for ITS. Based on the concatenated ITS and TEF1-α, a maximum likelihood phylogenetic analyses using MEGA7.0 clustered the isolate with C. cassiicola. Consequently, the fungus was identified as C. cassiicola based on its morphological and molecular features. In the pathogenicity test on 1-year-old Nanhaia speciosa seedlings, leaves were gently scratched and inoculated with mycelial plugs (5 mm). Control seedlings received PDA plugs. Five leaves per plant and five plants per treatment were selected for assessment. All seedling were maintained in a greenhouse (12/12h light/dark cycle, 25 ± 2°C, 90% humidity). After a 7-day incubation period, all leaves subjected to fungal inoculation exhibited symptoms consistent with those observed in the field, while control plants remained symptom-free. The fungus was successfully reisolated from the infected leaves in three successive trials, fulfilling Koch's postulates. While C. cassiicola is well-documented for inducing leaf spots on various plant species, including Jasminum nudiflorum, Strobilanthes cusia, Acanthus ilicifolius, Syringa species (Hu et al., 2023; Liu et al., 2023; Xie et al., 2021; Wang et al., 2021), this study represents the first report of C. cassiicola causing leaf spots on Nanhaia speciosa in China. The identification of this pathogen in Nanhaia speciosa has significant implications for future epidemiological investigations and serves as a valuable reference for controlling leaf spot disease in Nanhaia speciosa.

Colletotrichum horii and Colletotrichum fioriniae Causing Anthracnose on Star Anise (Illicium verum) in China.

Star anise (Illicium verum) is an important economic and medical plant widely cultivated in Guangxi province, China. Its fruit can be used as spice and medicine (Wang et al. 2011). In recent years, anthracnose led to a serious decline in the production of star anise in Guangxi. In 2021, a survey conducted in CenwangLaoshan Reserve of Guangxi (24°21'N; 106°27'E) showed that the 2500 ha planting area had disease incidence greater than 80%. The leaf symptoms initially appeared as small spots, then expanded to round spots, finally becoming withered with grayish-white centers, surrounded by dark brown margins. Sometimes, small black acervuli were observed in the later stage. To explore the pathogen, infected leaves were collected and cut into small pieces (about 5 mm2) from the edge of the lesion, disinfected with 75% ethanol for 10 s, 1% NaClO for 1 min, washed with sterilized water and incubated on potato dextrose agar (PDA) plates at 28 °C in the dark. Ten single-spore isolates were obtained from the cultures. After 7 days on PDA at 28 °C, the colonies of 7 isolates were white with abundant aerial hyphae, gray-black with white-gray margins, and the other 3 isolates were light gray on the upper surface, and pink or orange on the underside. Representative isolates BS3-4 and BS3-1 were selected from 3 isolates and 7 isolates, respectively. Conidia of BS3-4 and BS3-1 were both hyaline, cylindrical, aseptate, smooth, apex obtuse, base truncate, and no significant differences (P > 0.05) in size between BS3-1 (13.22 to 5.38 × 3.89 to 1.99 µm) (n = 50) and BS3-4 (12.04 to 4.34 × 3.48 to 1.64 µm) (n = 50). These morphological characteristics were consistent with the Colletotrichum ssp. (Damm et al. 2012). The species identification of BS3-4 and BS3-1 was performed based on DNA sequence analysis. Genomic DNA was extracted as a template. Partial sequences of the rDNA internal transcribed spacer (ITS), actin gene (ACT), ß-tubulin2 (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were amplified and sequenced (Weir et al. 2012). The sequences were deposited in GenBank (ITS:OQ062642-43; ACT:OQ067614-15; GAPDH:OQ067616-17;TUB2：OQ067618-19). Based on the concatenated sequences of the 4 genes (ITS-ACT- GAPDH -TUB2) of BS3-4 and BS3-1 as well as sequences of other Colletotrichum spp. obtained from GenBank, the Maximum likelihood (ML) tree which produced with IQ-TREE (Minh et al. 2020) revealed that the isolate BS3-1 was Colletotrichum horii, and BS3-4 was Colletotrichum fioriniae. Pathogenicity was confirmed on healthy leaves of 1-year-old star anise seedlings (cultivar Dahong), and the leaves were wounded by sterilized toothpicks, and were inoculated with 10 µl of conidial suspensions of BS3-1 and BS3-4 (106 conidia/ml). Control seedlings were inoculated with sterilized distilled water. Five leaves per plant and 3 plants per treatment were selected. All inoculated seedlings were maintained in the greenhouse (12/12h light/dark, 25 ± 2℃, 90% relative humidity). Wound sites inoculated with BS3-1 and BS3-4 both turned greenish-brown after 2 days and then turned light brown with water-soaked spots. Black (BS3-1) or orange (BS3-4) dots of acervuli developed after 6 days. The lesion diameter of BS3-1 (14.4 mm) was larger than that of BS3-4 (8.1 mm). No symptoms were observed on controls. BS3-1 and BS3-4 were re-isolated from inoculated leaves, fulfilling Koch's postulates. Anthracnose of star anise caused by C.horii has been reported in China (Liao et al. 2017). However, to our knowledge, this is the first report of C.fioriniae infecting star anise in China. Accurate pathogen identification in this study could provide a reference for the control of anthracnose on star anise.

New antifungal cycloheximide epimers produced by Streptomyces sp. YG7.

A couple of new cycloheximide epimers, 13(α)-acetoxy-anhydroisoheximide (1) and 13(ß)-acetoxy-anhydroisoheximide (2), together with six known compounds (3-8), were obtained from the cultures of Streptomyces sp. YG7. The structures were elucidated based on a comprehensive spectroscopic data analysis including 1D and 2D NMR, as well as HRESIMS, and by comparison with the literature. The X-ray crystal analysis of 1 further confirmed the structure. All the compounds were tested for antifungal activity. Compounds 1, 2 and 5-8 showed moderate Canidia albicans inhibitory activity, while 5 and 6 presented moderate Pyricularia oryzae inhibitory activity. [Formula: see text].

First Survey of the Pathogenic Fungus Batrachochytrium dendrobatidis in Wild Populations of the Yunnan Caecilian (Ichthyophis bannanicus) in Guangxi, China.

Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, mainly infects Anura and Caudata but is poorly known in Gymnophiona. We conducted a survey of Bd in the Yunnan caecilian (Ichthyophis bannanicus) and found that 6 of 71 samples (8.4%) tested positive for Bd. To our knowledge, this is the first detection of Bd in wild I. bannanicus.