Aspergillus spp. mycotoxins infect corn, cotton, sorghum and nuts. Controlling mycotoxin biosynthesis or fungal development would decrease its devastating health and economic impact. Because signaling pathways tend to be conserved in Aspergillus spp, the model system Aspergillus nidulans is used to study regulation of mycotoxin production and morphological development. Aspergillus spp. produce resistant structures: sclerotia in Aspergillus flavus and Aspergillus parasiticus and fruiting bodies called cleistothecia in A. nidulans. Because it is posited that sclerotia derive from cleistothecia that lost the capacity to produce spores, it is likely that conserved signaling pathways controlling cleistothecial development also control sclerotial formation in the major producers of the carcinogenic mycotoxin aflatoxin, A. flavus and A. parasiticus. Molecular studies over the control of cleistothecial or sclerotial development are limited. Only a few regulatory genes are known. We found that deletion of the veA gene completely blocks mycotoxin production as well as the formation of resistant structures in A. nidulans, A. flavus and A. parasiticus. We also found that morphological development and secondary metabolism is also controlled by this global regulator across genera. The VeA protein is a fungal-specific promising target for a control strategy;however, it does not present homology to previously described proteins. The main goal of this proposal is to further characterize the regulatory mechanism through which VeA controls mycotoxin biosynthesis and morphogenesis, particularly resistant structure development, in the model system, A. nidulans. In this study we propose to: 1. Characterize VeA interacting proteins, and 2. Generate and characterize suppressor mutants to identify the genetic elements downstream from veA involved in ST production. Because of the conserved nature of fungal regulatory networks across species and the fact that VeA has only been found in fungi, a control strategy involving VeA may be effective against mycotoxin contamination by Aspergillus spp. and against other plant and animal pathogens.
This AREA grant proposal involves the study of the mechanism of action of VeA, a fungal global regulator that controls the biosynthesis of secondary metabolites, such as potent carcinogenic mycotoxins, as well as development. In this study we propose to use the well known model filamentous fungus Aspergillus nidulans. VeA is conserved in different fungal species, particularly in Ascomycetes spp. The fact that VeA is unique to fungi and is conserved in different fungal species, makes veA a valuable possible target to control not only plant pathogens but human and animal pathogens. In this proposal we will examine 1. VeA interacting proteins involved in this regulatory system, and 2. Suppressor mutants to identify the genetic elements downstream from veA involved in mycotoxin production. These studies will provide valuable insight into this important fungal regulatory mechanism.
| Feng, Xuehuan; Ramamoorthy, Vellaisamy; Pandit, Sandesh S et al. (2017) cpsA regulates mycotoxin production, morphogenesis and cell wall biosynthesis in the fungus Aspergillus nidulans. Mol Microbiol 105:1-24 |
| Ramamoorthy, Vellaisamy; Dhingra, Sourabh; Kincaid, Alexander et al. (2013) The putative C2H2 transcription factor MtfA is a novel regulator of secondary metabolism and morphogenesis in Aspergillus nidulans. PLoS One 8:e74122 |
| Ramamoorthy, Vellaisamy; Shantappa, Sourabha; Dhingra, Sourabh et al. (2012) veA-dependent RNA-pol II transcription elongation factor-like protein, RtfA, is associated with secondary metabolism and morphological development in Aspergillus nidulans. Mol Microbiol 85:795-814 |
| Atoui, A; Kastner, C; Larey, C M et al. (2010) Cross-talk between light and glucose regulation controls toxin production and morphogenesis in Aspergillus nidulans. Fungal Genet Biol 47:962-72 |
