Roles of the Fungal-Specific Lysine Biosynthetic Pathway in the Nematode-Trapping Fungus Arthrobotrys oligospora Identified through Metabolomics Analyses.

In higher fungi, lysine is biosynthesized via the α-aminoadipate (AAA) pathway, which differs from plants, bacteria, and lower fungi. The differences offer a unique opportunity to develop a molecular regulatory strategy for the biological control of plant parasitic nematodes, based on nematode-trapping fungi. In this study, in the nematode-trapping fungus model Arthrobotrys oligospora , we characterized the core gene in the AAA pathway, encoding α-aminoadipate reductase ( Aoaar ), via sequence analyses and through comparing the growth, and biochemical and global metabolic profiles of the wild-type and Aoaar knockout strains. Aoaar not only has α-aminoadipic acid reductase activity, which serves fungal L-lysine biosynthesis, but it also is a core gene of the non-ribosomal peptides biosynthetic gene cluster. Compared with WT, the growth rate, conidial production, number of predation rings formed, and nematode feeding rate of the Δ Aoaar strain were decreased by 40-60%, 36%, 32%, and 52%, respectively. Amino acid metabolism, the biosynthesis of peptides and analogues, phenylpropanoid and polyketide biosynthesis, and lipid metabolism and carbon metabolism were metabolically reprogrammed in the Δ Aoaar strains. The disruption of Aoaar perturbed the biosynthesis of intermediates in the lysine metabolism pathway, then reprogrammed amino acid and amino acid-related secondary metabolism, and finally, it impeded the growth and nematocidal ability of A. oligospora . This study provides an important reference for uncovering the role of amino acid-related primary and secondary metabolism in nematode capture by nematode-trapping fungi, and confirms the feasibility of Aoarr as a molecular target to regulate nematode-trapping fungi to biocontrol nematodes.