Functional Analysis of Two Affinity cAMP Phosphodiesterases in the Nematode-Trapping Fungus .

Phosphodiesterases are essential regulators of cyclic nucleotide signaling with diverse physiological functions. Two phosphodiesterases, PdeH and PdeL, have been identified from yeast and filamentous fungi. Here, the orthologs of PdeH and PdeL were characterized in a typical nematode-trapping fungus by gene disruption and phenotypic comparison. Deletion of caused serious defects in mycelial growth, conidiation, stress response, trap formation, and nematicidal efficiency compared to the wild-type strain. In contrast, these phenotypes have no significant difference in the absence of . In addition, deletion of and resulted in a remarkable increase in cAMP level during vegetative growth and trap formation, and the number of autophagosomes was decreased in Δ and Δ mutants, whereas their volumes considerably increased. Moreover, metabolomic analyses revealed that many metabolites were downregulated in Δ mutant compared to their expression in the wild-type strain. Our results indicate that AoPdeH plays a crucial role in mycelial growth, conidiation, stress response, secondary metabolism, and trap formation. In contrast, AoPdeL only plays a minor role in hyphal and conidial morphology, autophagy, and trap formation in . This work expands the roles of phosphodiesterases and deepens the understanding of the regulation of trap formation in nematode-trapping fungi.