Investigating the Genes and Pathways Involved in the Biosynthesis of Indole-3-acetic Acid in 'Fusarium Graminearum'

The hormone indole-3-acetic acid (IAA) is utilized by some microorganisms as part of their infection strategy. This study investigated the enzymatic pathways and genes involved in the biosynthesis of IAA by F. graminearum. In culture, F. graminearum was able to produce IAA when supplied with tryptophan or intermediates found in the enzymatic pathways for the biosynthesis of IAA with the exclusion of indole-3-acetamide (IAM). Predicted gene function, gene expression profiling and RT-qPCR validation of specific gene expression patterns, allowed us to establish a list of candidate genes for the biosynthesis of IAA. A probable aldehyde dehydrogenase (fg02296) was inactivated by replacement in the F. graminearum genome. Results suggested that this gene is not required for IAA production or fitness level in F. graminearum. The role of IAA produced by this pathogen remains elusive however this study has provided some pertinent information on the biosynthesis of IAA in culture