|Bok, Jin Woo|
Submitted to: Molecular Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2010
Publication Date: 8/1/2010
Citation: Wiemann, P., Brown, D.W., Kleigrewe, K., Bok, J., Keller, N.P., Humpf, H., Tudzynski, B. 2010. FfVel1 and FfLae1, components of a velvet-like complex in Fusarium fujikuroi, affect differentiation, secondary metabolism, and virulence. Molecular Microbiology. 77(4):972-994. Interpretive Summary: This research identified and characterized a global regulatory complex of Fusarium that is involved in the synthesis of a number of different secondary metabolites including toxins and pigments. This is important because understanding the genetic mechanisms that control or influence how or when fungal toxins are synthesized is critical to our strategy to develop novel strategies to limit their contamination of agricultural commodities. We used a combination of heterologous cloning, microarray analysis, and microscopy to identify and characterize two genes that play key roles in this global regulatory complex. We found, for the first time, an example where this complex can simultaneously act as a positive (gibberellins and fumonisins) and a negative (bikaverin) regulator of secondary metabolism. Understanding how Fusarium regulates synthesis of multiple chemicals on a global scale will allow us to develop new strategies to limit disease and contamination of food and/or feed with toxins.
Technical Abstract: Fusarium fujikuroi is a pathogen of rice and is used industrially to produce gibberellins (GAs). It can also synthesize variety of other, contaminating secondary metabolites including the pigment bikaverin and the mycotoxins fumonisins and fusarin C. The global regulation of the biosynthetic pathways leading to these different materials is poorly understood. Recently, the Velvet complex, containing VeA and several other regulatory proteins, was shown to be involved in global regulation of secondary metabolism and differentiation in Aspergillus nidulans. Here we report on the characterization of two components of the F. fujikuroi Velvet complex, FfVel1 and FfLae1 FfVel1, identified by heterologous cloning, and FfVel1, identified by microarray analysis, interact in the nucleus similar to other Velvet complexes. This is the first LaeA homolog outside the class of Eurotiomycetidae identified as a target of Vel1. Deletion of Ffvel1 and Fflae1 revealed for the first time that Velvet can simultaneously act as a positive (GAs and fumonisins) and a negative (bikaverin) regulator of secondary metabolism, and that both genes affect conidiation and virulence of F. fujikuroi on rice.