Investigating the influence of antagonistic fungi Polydomus karssenii and Niesslia gamsii on the penetration of Heterodera filipjevi and Pratylenchus thornei in wheat

Plant parasitic nematodes (PPNs) significantly impact global wheat production. Strategies for managing PPN include developing tolerance/resistance varieties, crop rotation, and the use of nematicides. However, nematicides are highly toxic and have a non-target effect on the soil biota, emphasizing the need for safer alternatives and innovative approaches. This study investigated the suppressive effect of two nematode egg parasitic fungi, Polydomus karssenii (Ashrafi, Maciá-Vicente & Maier, 2023) and Niesslia gamsii (Ashrafi & Maier, 2017), on the penetration of the cereal cyst nematode (CCN) Heterodera filipjevi (Madzhidov, 1981) and the root lesion nematode (RLN) Pratylenchus thornei (Sher & Allen, 1953) into wheat roots. Two nematode-susceptible wheat cultivars, Bezostaya and Seri, were treated with P. karssenii and N. gamsii . Germinated seeds were dipped in a fungal suspension before being inoculated with the nematode species. Nematode penetration was evaluated at 48 h, 72 h, and 1 week after inoculation using acid fuchsin staining and microscopical examination. The results revealed that both fungal treatments reduced nematode penetration in both cultivars compared to untreated controls, with P. karssenii showing higher overall effectiveness. Polydomus karssenii reduced penetration of H. filipjevi by 91.9% and P. thornei by 85.9%, while N. gamsii reduced penetration of H. filipjevi by 76% and P. thornei by 67.3%. Additionally, fungal treatments delayed nematode penetration, no penetration was observed at 48 h in treated plants, while nematode penetration was observed in untreated plants during the same period. This study underscores the potential of P. karssenii and N. gamsii as sustainable biological agents against nematodes and emphasizes their role in integrated pest management strategies for wheat production. • Polydomus karssenii reduced nematode penetration by just over 90%. • Niesslia gamsii showed a 67-76% reduction in nematode penetration. • Both fungi delayed nematode penetration in wheat roots by 48 h. • First report of a dark septate endophyte ( Polydomus karssenii ) reducing/delaying penetration of plant parasitic nematodes.