Study On Ammonia Permeases In Arthrobotrys Oligospora And Trap-induced Compounds In Nematode

The former researches have indicated that some bacteria can produce urea to induce trap formation in A. oligospora to kill nematode. NH3, as one of the downstream mediator of urea, has been proved to induce trap formation in A. oligospora. In our research, we knocked out Ammonia permease genes AmtB80、AmtB43 and AmtB6 to study the molecular mechanism of trap-inducing of NH3 in A. oligospora. Nematode can induce trap formation in nematode-trapping fungi, we have got trap-induced compound from the C. elegans metabolites through the activity-guided isolation. It’s generality in other nemateode-trapping fungi and other nematodes have been tested. The results were as follows:1. Three genes of Ammonia permease in Arthrobotrys oligospora were knocked out, and three mutant strainsAAmtB80,ΔAmtB43 and ΔAmtB6 were obtained, which had been compared with wild stain in growth rate, mycelial morphology, response to nematode, response to NH3, conidia level, and osmotic tolerance. The results showed that response to NH3 of mutant strains were significantly reduced, conidia levels were also significantly lower than wild strain, and other indexes showed insignificantly change comparatively with wild strain.2. The compound WF4-1 was separated from the C. elegans metabolites, which had trap-inducing activity. It showed the best trap-inducing activity in A. oligospora at concentration of 0.02 mg/mL. The trap-inducing generality assay showed that six nemateode-trapping fungi could respond to this compound, among which, Arthrobotrys oviformis YMF1.03316, Arthrobotrys guizhouensis YMF1.00014and Arthrobotrys oligospora YMF 1.01883 could produce adhesive networks, Drechslerella effuse YMF 1.00583 and Drechslerella coelobrocha YMF 1.01480 could yield constricting rings, and Dactylelina leptospora YMF1.01460 could generate adhesive knobs. Moreover, LC-MS assay showed that the compound also existed in Panagrellus redivevus metabolites.The novelties of this study1. Three kinds of genes of Ammonia permease in Arthrobotrys oligospora were knocked out for the first time.2. Obtaining of trap-induced compound though activity-guided isolation from the C. elegans metabolites for the first time.