Differential Expression of the Catalase and Superoxide Dismutase Genes in Maize Ear Shoot Tissues

摘要

The temporal expression of two major antioxidant gene-enzyme systems, catalases and superoxide dismutases, has been characterized in the. husk leaf, silk, pistillate flower, whole kernel, and cob of the maize ear shoot. The catalase activity, CAT-2 and CAT-3 protein levels, and the steady-state mRNA levels of each of the threeCatgenes reveal differential expression of these transcripts in tissues of the ear shoot. AlthoughCat1andCat3expression is observed in all the aforementioned tissues,Cat2expression is detected only at the late stages of whole kernel maturation. Because silk exhibits the same pattern ofCatgene expression as the pericarp, and both tissues share an identical histological origin, catalase gene expression might be associated with cell lineage. The levels of total superoxide dismutase activity and corresponding individualSodtranscripts are fairly constant throughout the temporal profiles of the ear shoot tissues. However, the degree of accumulation of the multipleSodmRNAs in the husk leaf is higher than in the cob. The possibility that the relative position of a tissue within the ear shoot influences the degree of accumulation of the variousSodmRNAs is discussed.