Biological characterization and in vitro fungicide screenings of a new causal agent of wheat Fusarium head blight in Tibet, China

Abstract

Wheat (Triticum aestivum L.) is an important cereal crop, widely grown throughout the temperate zones, and also suitable for cultivation at higher elevations. Fusarium head blight (FHB) is a highly destructive disease of wheat throughout the globe. In July 2020, serious wheat FHB symptoms were observed in open fields located in Linzhi City, southeast of Tibet, China. The causal agent was identified as Fusarium avenaceum (Fr.) Sacc. by amplification and sequencing of the internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (EF-1α) gene, and RNA polymerase II subunit (RPB-2) gene, as well as by morphological characterization. Koch’s postulates were confirmed by a pathogenicity test on healthy spikes, including re-isolation and identification. To our knowledge, this is the first report of F. avenaceum causing FHB on wheat in Tibet, China. Moreover, to determine pathogen characteristics that may be useful for future disease management, the utilization of different carbon and nitrogen resources, temperature, light, and ultraviolet (UV) irradiation on mycelium growth and conidia germination were studied. Soluble starch and peptone were the best carbon, and nitrogen source for the pathogen respectively. The optimal temperatures for the pathogen’s mycelium growth and conidia germination were 15–20°C, matching the average temperature during the growing season in Linzhi (Tibet). Meanwhile, alternating 8-h light and 16-h dark was shown to be conducive to mycelia growth, and complete darkness facilitated conidia germination. In addition, UV Irradiation of 48 MJ/cm2, approximately 100 times of the local condition, did not inhibit the germination of conidia. Furthermore, in vitro screening of effective fungicides was conducted. Among the seven tested pesticides, carbendazim showed the best inhibition rate, with an EC50 (concentration for 50% of maximal effect) value of 2.1 mg/L. Propiconazole also showed sufficient inhibitory effects against F. avenaceum, with an EC50 value of 2.6 mg/L. The study provides insights into the newly identified causal agent of wheat FHB in Tibet, China, as well as first pathogen characteristics and promising candidate substances for its management.

Phytochemicals demonstrate potential fungicidal activity against Fusarium commune, a newly identified pathogenic fungus causing rhizome rot in Polygonatum cyrtonema (giant Chinese Solomon's seal)

“…In this study, mycelia of F. commune grew in all the carbon sources tested, and the fastest growth was observed in the medium with soluble starch as a carbon source. Similar to our findings, F. avenaceum and F. graminearum were reported to grow fastest in medium with soluble starch as a carbon source (Chen, Ran, et al., 2022; Tang et al., 2022). For oomycete plant pathogens, the types of carbohydrates used as an energy source may influence the production, liberation and germination of zoospores outside the root and oospore formation inside the root (Papavizas & Ayers, 1964).…”

“…Studies have shown that that F. oxysporum hyphae can grow under alternating light and dark periods (Shao et al, 2014). Tang et al (2022) found that an alternating cycle of 8 h of light and 16 h of dark is beneficial for the growth of F. avenaceum hyphae. However, Costa et al (2021) did not observe a significant difference in the germination and growth of F. fujikuroi under different light and dark conditions.…”

Identification of a new root rot-causing pathogen in Polygonatum cyrtonema Hua and screening of phytochemicals for its control

“…In this study, mycelia grew in all the carbon sources tested, and the fastest growth was observed in the medium with soluble starch as a carbon source. Similar to our findings, Fusarium avenaceum and F. graminearum were reported to grow fastest in medium with soluble starch as a carbon source (Tang et al 2022;Chen et al 2022b). The types of carbohydrates used as an energy source may influence the production, liberation, and germination of zoospores outside the root and oospore formation inside the root (Papavizas and Ayers 1964).…”

“…These findings suggest the importance of considering photoperiod as a factor in the development of management strategies for Fusarium related plant diseases. Chemical fungicides are commonly used as the main control measure for plant pathogens (Tang et al 2022;Chen et al 2022c). However, their improper use can pose safety hazards.…”

Plant Growth Promotion and Biocontrol of Leaf Blight Caused by Nigrospora sphaerica on Passion Fruit by Endophytic Bacillus subtilis Strain GUCC4

“…In major crops, productivity losses due to different kinds of plant diseases range from 21% to 31% worldwide [ 1 ]. In addition, many plant pathogens have developed resistance to different chemical pesticides [ 2 ]. Consequently, it has become difficult to control certain plant diseases due to the paucity of efficient compounds [ 3 ].…”