Analysis of transgenic tobacco that express maize catalase3
Schake, Sheryl A.
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Catalases (H2O2: H2O2 oxidoreductase, EC 188.8.131.52; CAT) are hemecontaining tetramers that are important in destroying H2O2 found in different cellular compartments. Maize Cats has been shown to be capable of dismutating H2O2 via either a catalatic or peroxidatic reaction. In addition, increased maize CAT3 transcripts were detected during periods of chilling acclimation. In this study, a maize CatS cDNA was isolated using reverse transcriptase polymerase chain reaction. To better understand the role of maize CAT3 in oxidative stress, we have introduced the transgene that expresses this enzyme into wild type Xanthi NN tobacco (Nicotiana tabacum). Total catalase activities were only slightly higher in transgenic plants as compared to Xanthi NN. While total peroxidatic activity of these transgenic plants was found to be 12-fold higher than in the wild-type tobacco. Thetransgenic Cat3 plants were exposed to various abiotic stresses such as, low temperatures, high temperatures, salinity, chemical treatments, and photooxidation. Increased seedling growth was evident in transgenic seedlings during treatments at low temperatures, high temperatures, and salinity which could implicate increased protection from oxidative damage. No significant protection was evident when transgenic seedlings were treated with methyl viologen or photooxidatlve stress. In addition, lower lipid peroxidation levels in transgenic plants correlated with increased peroxidatic activity in these plants. These data suggests that in wild-type tobacco that express maize CAT3 have increased protection against various forms of oxidative stress.