Figure 2. Sulfur atoms from fungal volatiles are incorporated into plant tissues. Shown are34S/32S ratios of glucosinolates and glutathione in shoot (A) and root (B) tissues. M. hyalina was grown on modified KM plates with addition of 32S -ammonium sulfate (unlabeled) or 34S-ammonium sulfate (labeled), and co-cultivated with Arabidopsis seedlings in a desiccator. Ratio of 34S over 32S of each glucosinolate species and glutathione was computed from M+2 and M peaks in LC-MS chromatogram. Error bars represent SEs from 3 independent biological replicates, each contains 4 technical replicates from 16 seedlings. Asterisks indicate significance level from Student’s T-test between unlabeled and labeled samples (*P < 0.05; **P < 0.01). n.d.: not detected. 4MOI3M: 4-Methoxy-3-indolylmethyl glucosinolate; I3M: 3-Indolylmethyl glucosinolate; 8MSOO: 8-Methylsulfinyloctyl glucosinolate; 4MTB: 4-Methylthiobutyl glucosinolate; 4MSOB: 4-Methylsulfinylbutyl glucosinolate; GSH: Glutathione. Detailed structure of the molecule examined can be found in Figure S3 and S4.