Thermotolerant strain <i>02</i> responded to heat stress with more PABA synthesis than strain <i>8213</i>.

<p>(A) MS/MS analysis identifies the protein spot 36 to be mushroom PABA synthase. (B) Differential transcription of PABA synthase gene <i>Pabs</i> in strain <i>02</i> and strain <i>8213</i> with or without heat stress. Strain <i>02</i> and strain <i>8213</i> were treated with high temperature at 33°C for the indicated time and the mRNA level of <i>Pabs</i> was quantified by real-time PCR. Three independent biological replicates were performed. Data are expressed as average ± SEM. Unpaired t-tests were performed between high temperature treatment samples and control samples (without treatment) within each strain, respectively, ns: P>0.05, *: P<0.05, **: P<0.01. (C) Differential protein accumulation of PABA synthase in strain <i>02</i> and strain <i>8213</i> after heat stress. Strain <i>02</i> and strain <i>8213</i> were treated with high temperature at 33°C for the indicated time, and PABA synthase protein levels were measured by western blot as indicated. (D) Differential accumulation of PABA content in strain <i>02</i> and strain <i>8213</i> after heat stress. Strain <i>02</i> and strain <i>8213</i> were treated with high temperature at 33°C for the indicated time and the content of PABA was measured by HPLC. Three independent biological replicates were performed. Data are expressed as average ± SEM.