Objective 3. Better Understand the Biology and Ecology of Mycotoxigenic Fungi.
<p>Objective 1: Identify global regulators of mycotoxin biosynthesis and assess their impact on fungal development. The finding of LaeA as a conserved regulator of both mycotoxin production and sporulation in all mycotoxin producing genera has focused attention on this protein as a tool to identify pathways required for not only fungal toxin synthesis but of most important developmental processes such as production of asexual spores or overwintering structures (e.g. sclerotia produced by A. flavus). We have recently identified another global regulator of mycotoxin synthesis in A. nidulans that we call LaeB. We will investigate if this protein is also important in A. flavus aflatoxin synthesis and fungal growth.We will also focusing on a particular lectin binding protein called FleA regulated by LaeA in A. flavus and A. fumigatus. Preliminary data suggests FleA is located on the spore wall and we hypothesize that it is involved in adherence of fungal spores to host tissues (e.g. seed).</p><p>Objective 2: Identification of quorum sensing programs in mycotoxigenic Aspergilli. Past work identified the LaeA regulated duplicated gene clusters that we found to encode redundant small molecules required for sclerotial production. We will confirm that the small molecules produced by the lna and lnb gene clusters are involved in quorum sensing and required for sclerotial formation through feeding strategies (e.g. does addition of these piperazine-like molecules induce sclerotial productions? our primary data suggests this to be so). This aim will identify the fungal receptors required for recognition of ligands (including but not limited to lna/lnb metabolites) necessary for quorum sensing. We will work with 14 G protein coupled receptors (GPCR), ultimately deleting all and couple them with ligands. In addition to testing all mutants for defects in quorum sensing, all mutants will be examined for their ability to colonize host seed and respond to host metabolites.</p>