Peroxidase Activity in the Maize Stature Mutant Nana-1

One cause of dwarfing in Nana-1 has been attributed to a lack of sufficient auxin produced by the dwarf coleoptile (Van Overbeek, 1935) and the greater destruction of auxin in the dwarf mesocotyl by peroxidases (Van Overbeek, 1938). The functions and activities of peroxidase enzymes are varied with regard to the type of reaction catalyzed and the target tissue. Hall, et al., (1969) investigated isoenzyme fractions from a number of plants and found the peroxidases to be distributed throughout a wide variety of green plants representing eleven genera. Brown (1961) found peroxidases were able to mediate the formation of lignin, while Parish (1969) found no close relationship between lignin content and peroxidase activity. Peroxidase activity has been associated with growth (Haskins, 1955) in that tissues which are undergoing rapid growth exhibited a greater amount of peroxidase activity when compared to more mature, slower growing tissue. Different results were reported by Galston and Dalberg (1954) which led them to the conclusion that as the age of the tissue increases, the activity of IAA-oxidase, a peroxidase, increases. Similar results were reported (Katsumi and Sano, 1968) which indicated an inverse relationship between IAA-induced elongation and the activity of IAA-oxidase in the seedlings of light-grown cucumbers. Pilet and Dubouchet (1961) determined that maximum growth in the coleoptiles of wheat occurred in the zone where enzymatic degradation of auxin was least.