ARS | Publication request: Nitric Oxide Metabolism and the Role of NO Detoxifying Flavohaemoglobin in Fusarium verticillioides

Submitted to: Fungal Genetics Conference/Asilomar
Publication Type: Abstract Only
Publication Acceptance Date: February 3, 2011
Publication Date: N/A

Technical Abstract: Nitric oxide (NO) is a small free radical, highly reactive, and responsible for both cytotoxic and cytostimulant effects in the cell. The dual nature of NO makes it the perfect candidate for both molecular signaling and an effective first line of defense against pathogens. Fusarium verticillioides is a non-obligate pathogen causing a number of maize diseases. One possible determinate of its pathogenesis could be the regulation of NO crosstalk with its maize host. Detoxification of NO is a known pathogenicity factor for the fungal human pathogen Candida albicans and the bacterial plant pathogen Erwinia chrysanthemi, requiring a flavohaemoglobin protein for this detoxification (CaYHB1 and HmpX, respectively). BLASTP search of the F. verticillioides genome revealed two putative flavohaemoglobin homologs, denoted NOD1 and NOD2 (for Nitric Oxide Dioxygenase). deltaNOD1 mutants sequestered NO in vacuoles, whereas wild type accumulated NO in the cytoplasm. This accumulation may be a cellular response to the inability to detoxify the NO generated by the fungus. deltaNOD2 mutants are being developed and both gene deletions will be evaluated for growth and development phenotypes and their virulence against maize seedlings.