Thioredoxin1 regulates conidia formation, hyphal growth, and trap formation in the nematode-trapping fungus Arthrobotrys oligospora

Purpose Arthrobotrys oligospora, a model nematophagous fungus that produces specific adhesive networks to capture nematodes, has been proposed as a potentially effective biological agent to control harmful plant-parasitic nematodes. Although thioredoxin has been characterized as playing important roles in many cellular processes in other species, its function in nematophagous fungi has not been studied. Here, the function of a thioredoxin homolog, Aotrx1, was investigated in A. oligospora. Methods The encoding gene of Aotrx1 in the nematophagous fungus A. oligospora was knocked out by homologous recombination; strain growth was assessed. Results The Delta Aotrx1 strain of A. oligospora showed a significant decrease in growth rate on different media (PDA, CMY, and TG), a 70% decrease of conidia production, and a lower germination rate compared with the wild type. The mutant strain was unable to form traps to capture nematodes and was more sensitive to SDS and H2O2. Conclusion Thioredoxin is involved in conidia development, trap formation, normal mycelial growth, and resistance to environmental stresses in the nematode-trapping fungus A. oligospora.