XVI International Botanical Congess

We have produced transgenic potato plants with severely reduced amounts of serine hydroxymethyltransferase (SHMT). The antisense construct harboured a full-length potato cDNA encoding SHMT under control of the potato ST-LS1 promoter. These plants have been analysed as yet according to their amino acid content and several parameters of CO2 exchange. Major effects (up to 100fold elevated levels) were observed with respect to the glycine content of leaves. Photosynthesis rates are decreased. The degree of this reduction is correlated with glycine levels, i.e., with the reduction in SHMT activity. Post-illumination CO2 bursts are increased. All these effects were greatly elevated by higher light intensity. Two lines were unable to grow under moderate light intensities and ambient air but could be recovered in 2000 micro l l-1 CO2.