RESEARCH REPORTS                                                             TGC REPORT 52, 2002 ______________________________________________________________________                             found that amounts of Lys, Arg, Asp, Glu, Val, Met, Leu, iLeu, Tyr and Phe were higher in  transgenic  fruits  and  the  content  of  Pro,  Gly  and  Ala  were  lower.  If  the  change  in amino acids composition in fruit and the increase in vitamin C can be accompanied with change in other substances (i.e. carotenoids) and influence the fruit nutritional value will be  a  point  to  investigate.  Larger  pool  of  lower  molecular  weight  compounds,  such  as amino acids, in plants has the role to balance the osmotic pressure in cells in order to overcome water stress. Table 2. Total amino acids contents in leaves and fruits of tomato cv. Ventura (nmol/g fresh weight). Leaves Green fruits Red fruits Control 4206.2 5208.4 5557.5 Transgenic 4931.3 6349.1 8899.5 Leaves  of  transgenic  plants  cv  Ventura  contained  more  water  then  the  control (Table  1),  perhaps  the  abundance  of  low  molecular  weight  compounds  balanced  the osmotic  pressure  in  cells  in  order  to  maintain  water  content  high  and  to  overcome drought and water stress. Measurement of leaf gas exchange (Table 3) indicated that the Ventura transgenic plants have higher net carbon dioxide assimilation and lower stomatal conductance and water transpiration indicating a possible higher efficiency of water use. Table 3. Comparison of leaf gas exchange between control and transgenic tomato. Net photosynthesis Water vapor transpiration Stomatal Conductance mmol m-2s-1 mmol m-2s-1 mol m-2s-1 30th June Control 11.20±0.2199 11.07±0.003483 1.791± 0.7129 Transgenic 13.35±0.2610 9.073±0.003649 0.8248±0.1983 31st July Control 12.56±0.6676 12.40±0.1264 1.647±0.6759 Transgenic 15.55±0.4139 9.888±0.09210 0.8225±0.2395 During Siberian summer the tomato cultivation occurred under a plastic greenhouse and hot temperatures occurred sometimes. In this condition both control and transgenic plants  wilted  but  the  recovery  was  faster  in  transgenic  tomato  plants  than  in  control 19

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