INHIBITION OF CAT ENZYME-ACTIVITY IN ARABIDOPSIS-THALIANA

Previously it was shown that transient chloramphenicol acetyltransfera se (CAT) marker gene expression in Arabidopsis thaliana and Nicotiana tabacum resulted in significant differences in the accumulation of the CAT reaction products in radioactive CAT assays. Compared to Nicotian a tabacum, conversion of chloramphenicol to the acetylated products in Arabidopsis thaliana extracts was rather low. Here we report that the low CAT enzyme activity can be attributed in part to a heat sensitive CAT inhibitory effect in extracts of Arabidopsis thaliana. CAT enzyme acitvity in transgenic tobacco is inhibited by extracts from Arabidop sis. This inhibitory effect diminishes when Arabidopsis extracts were heat incubated. CAT activity in transgenic Arabidopsis lines was very low and was only detected in heat incubated extracts. Alternatively, e nzyme-linked immunosorbent assays (ELISAs) can be used to detect the C AT protein in transgenic Arabidopsis.