Targeting polyamines of Aspergillus nidulans by siRNA specific to fungal ornithine decarboxylase gene.

Aspergillus nidulans is a filamentous, ubiquitous and opportunistic pathogenic fungus, which causes fatal invasive aspergillosis among immunocompromised patients. As a prelude to the investigations on the possible control of human fungal diseases by selective targeting of fungal polyamines that are essential for fungal growth and development by RNAi strategy, we have examined the effect of siRNA specific to a key polyamine biosynthesis gene ornithine decarboxylase (ODC) on the in vitro germinating spores of A. nidulans to assess the ability of RNA species to induce RNA-mediated gene silencing. The present findings show that siRNA can cause specific silencing effect, with the phenotypic consequences leading to significant reduction in mycelial growth, target mRNA titers and cellular polyamine concentrations. This study suggests that fungal polyamine biosynthetic genes, particularly ODC may be targeted for the control of fungal infections in humans and crop plants. To the best of our knowledge, this is the first demonstration of up-take of siRNA by germinating fungal spores from culture medium, and attempt to target a vital pathway in fungal pathogens for their control.