The Role of Nitrogen Oxide in Photomorphogenesis in Neurospora сrassa

Resumo

The role of nitric oxide in the photomorphogenesis of several Neurospora сrassa strains (the wild-type strain wt-987, the nit-2 mutant, which lacks nitrite and nitrate reductase, and the nit-6 mutant, which lacks nitrite reductase) was evaluated from the content of nitrate and nitrite, the final products of NO decomposition, in the mycelium and cultivation medium. Analysis of the dynamics of nitrite release from the mycelium of the N. crassanit-6 strain in the course of photostimulated conidiogenesis indicated the possible participation of the NO-generating mechanism in the fungal photosignal transduction. Light-regulated conidiation in N. crassa was inhibited by the introduction of S-nitrosoglutathione, a nitrogen oxide donor, to the cultivation medium, and stimulated by the introduction of L-nitroarginine, an inhibitor of NO synthase, which is inderect indicative of the role of NO in the process. However, the absence of \({\text{NO}}_{2}^{ - }\) release during the photostimulated development of the protoperithecia (precursors of the female sexual structures) indicated a low probability of NO participation in sexual propagation of the fungus.