H2S and COS Gas Exchange of Transgenic Potato Lines with Modified Expression Levels of Enzymes Involved in Sulphur Metabolism

Different transgenic potato lines were generated for improving the nutritional value of tubers by an advanced perception of their sulphur metabolism. So far no data exist about possible implications for plant health and stress resistance. Metabolite analysis revealed that modifications of enzymes involved in sulphur metabolism were necessarily not reflected in distinctly altered thiol contents. The release of H 2 S by plants is putatively involved in pathogen resistance, because of its fungi-toxic mode of action. The emission of H 2 S was determined in 16 potato lines with modified expression level in ATP sulphurylase (ATPS), serine acetyltransferase (SAT), O-acetylserine(thiol)lyase (OASTL), homoserine kinase (HSK) and threonine synthase activities. The emission significantly increased by factor 7 in one of the ATPS antisense lines and by factor 8 in one of the OASTL antisense lines. A strong increase in H 2 S emissions was observed in transgenic plants based on the potato cultivar White Lady, which expressed the Escherichia coli SAT. In addition, the exchange of COS was determined in relation to genetic modifications. Generally, plants act as a sink for COS, but all transgenic lines expressing the E. coli HSK and one of the ATPS antisense lines emitted COS indicating to strong changes in the metabolism of these plants. Such alterations in the gas exchange of transgenic potato plants will most likely also affect their resistance against biotic and abiotic stress.