Analysis of the Mycotoxin Levels and Expression Pattern of SWN Genes at Different Time Points in the Fungus .

The fungal plant pathogen produces two mycotoxins that affect animals: slaframine, which causes slobbers, and swainsonine, which causes locoism. contains the swainsonine-associated orthologous gene clusters, "SWN", which include a multifunctional gene (NRPS-PKS hybrid), and (nonheme iron dioxygenase genes), and (reductase genes), and swnT (transmembrane transporter). In addition to these genes, two paralogs of , (paralog1) and (paralog2), are found in . cDNAs from total mRNA were isolated from the mycelia grown in the culture plates as well as from leaves inoculated with the fungal mycelia at different time points, and expression pattern of the SWN genes were analyzed using RT-qPCR. The concentrations of swainsonine and slaframine production from this fungus at different time points were also examined using liquid chromatography-mass spectrometry. The timing of gene expression was similar in cultured fungus and inoculated leaves and agreed with our proposed biosynthetic pathway. Substantially more swainsonine was produced than slaframine during time course studies.