5% Tween 60 solution (Leslie & Summerell, 2006). For outcrosses, the heterothallic female strains were fertilized with 1 mL of a conidial suspension (106 conidia mL−1) from male strains as previously described (Lee et al., 2003). All of the cultures were incubated under near UV light (wavelength: 365 nm) at 25 °C. For trichothecene (deoxynivalenol and 15-acetyldeoxynivalenol) analysis, the conidial suspension was inoculated in defined media containing 5 mM of agmatine (MMA) as previously described (Gardiner et al., 2009). Culture filtrates were extracted with ethyl acetate/methanol mixture (4 : 1, selleckchem v/v) (He et al., 2007). The resulting trichothecenes were analyzed with a Shimadzu
QP-5000 gas chromatograph-mass spectrometer (GC-MS; Shimadzu, Kyoto, Japan) as previously described (Seo et al., 1996). To analyze zearalenone, mycelia of wild-type and transgenic strains that were grown in CM for 3 days, were subcultured into starch glutamate (SG) media and incubated for 7 days (Bacon et al., 1977). Culture filtrates were extracted and analyzed with a Shimadzu LC-6A HPLC as previously described (Kim et al., 2005a,b). The transcript level of TRI6 and ZEB2 gene was analyzed by quantitative
real-time PCR (qRT-PCR) as previously described (Lin et al., 2011). Briefly, total RNA was extracted from cultures in defined media containing 5 mM of agmatine at 4 days after inoculation (DAI) and in SG media at 7 DAI. The first strand cDNA was synthesized and qRT-PCR was performed. The selleck compound transcript level of TRI6 in MMA and ZEB2 in SG media was quantified with appropriate primer pairs (Table S1). The housekeeping gene CYP1 (Broad Institute ID: FGSG_07439.3) was used
as an endogenous control for normalization. PCR was repeated three times with three biological replicates per run. To observe GFP and red fluorescent protein (RFP), mycelia were collected by centrifugation and fixed with paraformaldehyde in phosphate-buffered saline (4% w/v) (Seong et al., 2008). Meiotic chromosomes were stained with acriflavin as previously described (Raju, 1986). The perithecia were dissected in one drop of 20% glycerol on a microscope glass slide Calpain and the rosettes of asci were gently flattened under the coverglass (Min et al., 2010). An Axio Imager 1 microscope (Carl Zeiss, Germany) was used for differential interference contrast and fluorescence observation (GFP excitation 470/40, emission 525/50; RFP excitation 546/12, emission 590). Nuclei stained with acriflavin were visualized with a GFP filter set. A blast search of the genomic sequence from G. zeae indicated that the fungus contains one copy of AreA homologue coding gene (areA, Broad Institute ID: FGSG_08634.3) with 85% sequence identity to the AREA-GF of G. fujikuroi (Tudzynski et al., 1999). The most conserved region of AreA homologues is a GATA-type zinc finger DNA binding domain. We employed a targeted gene deletion strategy to determine the roles of areA in G. zeae.