Sulfur atoms from TMTM are incorporated into plant metabolites
To test whether sulfur from TMTM is incorporated into plant material, we grew M. hyalina on modified KM medium with addition of32S- or 34S-ammonium sulfate, and co-cultivated them together with Arabidopsis seedlings in the same desiccator, but without direct physical contact. After 14 days, shoot and root tissues were collected, and the 34S/32S ratio of GSLs and GSH was analyzed with LC-MS. For the shoots, a significant increase of the 34S/32S ratios for the GSLs was detected (8.8%→12.8% for 4MOI3M; 8.4% → 12.6% for I3M; 14% → 16.6% for 8MSOO; 13.7% → 16.7% for 4MSOB; Figure 2; Figure S3 and S4). The ratio was also higher for the GSH in the shoots (4.4% → 6.3%). With the exception of 8MSOO, for which we also observed a significant increase in the roots (11.3% → 15.4%), the increases for the other compounds were much less (4.1% → 4.3%; Figure 2; Figure S3 and S4). In conclusion, sulfur from M. hyalina headspace are incorporated into plant GSLs and GSH material.