Ear rot caused by Fusarium species is one of the most serious diseases on maize in China. This disease reduces maize yield and kernel quality to a large extent. The mycotoxins in kernels produced b...

Orychophragmus violaceus is an annual or perennial herb in the Brassicaceae that is widely cultivated in China where it is mainly used for ornamental plants and forage grass. In 2017 a new leaf blight disease was found onO.violaceus from September to October in Hebei province, northern China. More than 80% of the leaves and 100% of the plants in the field were symptomatic. On the leaf blade, a small, irregular spot with an irregular shape gradually developed into a black disease spot with the obvious concentric wheel striatum. Symptomatic O.violaceus leaves were collected and surface disinfested with 75% ethanol and 10% sodium hypochlorite, rinsed three times with sterile distilled water, and placed onto potato dextrose agar (PDA). After 2 days of incubation at 25°C in the dark, newly grown-out mycelia were transferred onto fresh medium and purified by the single-spore isolation method. In PDA medium, Olive-green mycelium developed after 2 days of incubationat 25°C, turned dark green, and covered the petr...

Maize (Zea mays L.) is an economically vital grain crop that is cultivated worldwide. In 2011, a maize foliar disease was detected in Lingtai and Lintao counties in Gansu Province, China. The characteristic signs and symptoms of this disease include irregular chlorotic lesions on the tips and edges of infected leaves and black punctate fruiting bodies in dead leaf tissues. Given favourable environmental conditions, this disease spread to areas surrounding Gansu. In this study, infected leaves were collected from Gansu and Ningxia Hui Autonomous Region between 2018 and 2020 to identify the disease-causing pathogen. Based on morphological features; pathogenicity tests; and multi-locus phylogenetic analysis involving internal transcribed spacer (ITS), 18S small subunit rDNA (SSU), 28S large subunit rDNA (LSU), translation elongation factor 1-alpha (TEF), and β-tubulin (TUB) sequences, Eutiarosporella dactylidis was identified as the causative pathogen of this newly discovered leaf blight. Furthermore, an in vitro bioassay was conducted on representative strains using six fungicides, and both fludioxonil and carbendazim were found to significantly inhibit the mycelial growth of E. dactylidis. The results of this study provide a reference for the detection and management of Eutiarosporella leaf blight.

Maize (Zea Mays L.) is one of the main crops in Ningxia Province, China, and stalk rot has become a serious disease of maize in this area. Infected plants showed softening of the stalks at lower internodes, which lodged easily and died prematurely during grain filling, and the pith tissue internally appeared to be disintegrating and slightly brown to reddish. In September 2018, symptomatic tissue was collected from seventeen locations in Ningxia. The incidence ranged from 5% to 40% in surveyed fields, reaching as high as 86% in certain plots. The discolored stalk pith tissues from the lesion region were cut into small pieces (approximately 0.5 × 0.2 cm), superficially disinfected with 75% ethanol for 1 min and rinsed three times with sterile water before plating on potato dextrose agar (PDA) medium with chloromycetin. The purified strains were obtained by single-spore separation and transferred to PDA and carnation leaf agar (CLA) medium. Morphological and molecular characteristics confirmed the presence of nine Fusarium species in these samples, including Fusarium graminearum species complex and Fusarium verticillioides. Four isolates of Fusarium nelsonii were recovered from samples collected in Shizuishan and Wuzhong. On PDA plates, the floccose to powdery, white to rose-colored aerial mycelia were produced and covered plates after 8 days of incubation, producing abundant mesoconidia and chlamydospores. Mesoconidia were fusiform or lanceolate until slightly curved with 0-3 septa, and chlamydospores were initially smooth and transparent, and became verrucous and light brown. Macroconidia produced in CLA were straight or curved and falcate, usually having 3-5 septa, with beak-shaped strongly curved apical cells and foot-shaped basal cells. Two isolates (SS-1-7 and ZY-2-2) were selected for molecular identification, and the total DNA was extracted using a fungal genomic DNA separation kit (Sangon Biotechnology, Shanghai, China). Sequence comparison of EF-1α (GenBank accession numbers MW294197 and MW294198) and RPB2 (Accession MW294176 and MW294177) genes showed 97% homology with the sequences of F. nelsonii reported in GenBank (accession MN120760 for TEF and accession MN120740 for RPB2). Pathogenicity tests with two isolates (SS-1-7 and ZY-2-2) were performed by individually inoculating five 10-leaf stage maize plants at between the 2nd and 3rd stem nodes from the soil level with 20 μl conidial suspension at a concentration of 106 conidia/ml as described by Zhang et al. (2016). Five maize plants inoculated with sterile water were used as controls. The inoculated plants were kept at 25 ± 0.5°C in the greenhouse with a photoperiod of 12 h. After 30 days, all plants inoculated with the conidial suspension formed an internal dark brown necrotic area around the inoculation site, whereas the control plants showed no symptoms. The pathogen was re-isolated from the necrotic tissue of the inoculated plants and identified by morphological characteristics as F. nelsonii. This species was first described by Marasas et al. (1998), and it is expanding its host range and has been isolated from sorghum, Medicago, wheat, and cucumber (Ahmad et al. 2020). The pathogen should be paid more attention owing to a serious risk of trichothecene and aflatoxin contamination (Astoreca et al. 2019; Lincy et al. 2011). To our knowledge, this is the first report of maize stalk rot caused by F. nelsonii in China. References: Ahmad, A., et al. 2020. Plant disease.1542 https://doi.org/10.1094/PDIS-11-19-2511-PDN Astoreca, A. L., et al. 2019. Eur. J. Plant Pathol. 155:381. Lincy, S. V., et al. 2011. World J. Microbiol. Biotechnol. 27:981. Marasas, W. F. O., et al. 1998. Mycologia 90:505. Zhang, Y., et al. 2016. PLoS Pathog. 12:e1005485. Funding: This research was financially supported by National R & D Plan of China (No.2019QZKK0303); Ningxia Agriculture and Forestry Academy Science and Technology Cooperation Project (DW-X-2018019).

Epichloë endophytes have been found in cool-season grasses and can produce alkaloids that are toxic to vertebrates and insects. Due to their beneficial effects, Epichloë can provide plants with resistance to some abiotic and biotic stresses. The biological and physiological characteristics of the endophytic strains XJE1, XJE2, and XJE3 isolated from wild barley were measured across a range of pH, salt concentrations, and growth values. The phylogenetic position of the Epichloë isolates was examined using the tefA and actG genes. The optimal pH values for mycelial growth of XJE1, XJE2, and XJE3 were 7–8, 6–7, and 8–9, respectively. The isolates grew significantly better at 0.3 mol/L NaCl than at 0.5 mol/L and 0.1 mol/L NaCl. Based on the conidiophore and conidia morphology, growth characteristics, and phylogenetic relationships, the endophyte isolated from wild barley is likely Epichloë bromicola. These isolates exhibited differences in mating types and alkaloid biosynthesis genes. Screening for salt tolerance and alkaloid biosynthetic genes in endophytic strains will provide new insights into useful traits to breed into new forage germplasms.