Manipulation of Catalase Levels Produces Altered Photosynthesis in Transgenic Tobacco Plants¹

Louise F. Brisson², Israel Zelitch^*, and Evelyn A. Havir

Department of Biochemistry and Genetics, The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, Connecticut 06504

Constructs containing the cDNAs encoding the primary leaf catalase in Nicotiana or subunit 1 of cottonseed (Gossypium hirsutum) catalase were introduced in the sense and antisense orientation into the Nicotiana tabacum genome. The N. tabacum leaf cDNA specifically overexpressed CAT-1, the high catalytic form, activity. Antisense constructs reduced leaf catalase specific activities from 0.20 to 0.75 times those of wild type (WT), and overexpression constructs increased catalase specific activities from 1.25 to more than 2.0 times those of WT. The NADH-hydroxypyruvate reductase specific activity in transgenic plants was similar to that in WT. The effect of antisense constructs on photorespiration was studied in transgenic plants by measuring the CO₂ compensation point () at a leaf temperature of 38°C. A significant linear increase was observed in  with decreasing catalase (at 50% lower catalase activity  increased 39%). There was a significant temperature-dependent linear decrease in  in transgenic leaves with elevated catalase compared with WT leaves (at 50% higher catalase  decreased 17%). At 29°C, also decreased with increasing catalase in transgenic leaves compared with WT leaves, but the trend was not statistically significant. Rates of dark respiration were the same in WT and transgenic leaves. Thus, photorespiratory losses of CO₂ were significantly reduced with increasing catalase activities at 38°C, indicating that the stoichiometry of photorespiratory CO₂ formation per glycolate oxidized normally increases at higher temperatures because of enhanced peroxidation.

Plant Physiol. (1998) 116: 259-269
Copyright Clearance Center:   0032-0889/98/116/0259/11
© 1998 American Society of Plant Physiologists

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