Control plant-parasitic nematodes with Trichoderma species and nematode-trapping fungi: The role of chi18-5 and chi18-12 genes in nematode egg-parasitism

Eighteen strains of five Trichoderma species (Trichoderma atroviridae, Trichoderma harzianum, Trichoderma rossicum, Trichoderma tomentosum, Trichoderma virens) and six strains of four nematode-trapping fungi (Arthrobotrys oligospora, Arthrobotrys tortor, Monacrosporium haptotylum and Monacrosporium cionopagum) were tested in 90 combinations in order to identify the most appropriate partners to control plant-parasitic nematodes. In vitro monoculture growth rate tests, dual confrontation assays and comparison of strain specific egg-parasitic index (EPI) revealed that T. harzianum strains possess the strongest egg-parasitic ability and the best compatibility with M. cionopagum. Because Trichoderma chitinolytic enzyme systems play an important role in egg-parasitism the transcriptional activity of chi18-5 (chit42) and chi18-12 (chit33) of T. harzianum (SZMC 1647) during egg-parasitism were also characterized. The expression patterns of these genes revealed overlapping modes of action and elucidated differences in timing and amplitude of gene induction between the mycoparasitic and egg-parasitic processes.