Introduction

Abstract

Since their discovery by Hunter and Markert in 1957, isozymes have played a key role in many branches of biology. To date, they have become the most widely recognized links between the organismal and molecular approach to our science. Isozymes were originally defined by Markert and Moller (1959) as different variants on the same enzymes, having identical or similar functions, and present in the same individual. As such, their importance for understanding gene action in development and differentiation was exploited during the 1960s in both animals and plants. A review of this early work was made by Scandalios (1969) on six different kinds of enzymes. For some of them he noted differences in different parts of the same plant: both presence vs. absence, and quantitative differences in concentration.