Isozymes in Plant Biology

pp 5-45

Visualization and Interpretation of Plant Isozymes

  • Jonathan F. WendelAffiliated withDepartment of Botany Bessey Hall, Iowa State University
  • , Norman F. WeedenAffiliated withDepartment of Horticultural Sciences New York State Agricultural Experiment Station, Cornell University

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Gel electrophoresis of proteins has become a standard and powerful research tool for application in a multitude of biological disciplines. One form of protein electrophoresis, isozyme analysis, has become particularly prominent in systematic and evolutionary biology as well as agronomy (Tanksley and Orton, 1983). Isozymes, or multiple molecular forms of enzymes, are enzymes that share a common substrate but differ in electrophoretic mobility (Markert and Moller, 1959). They are revealed when tissue extracts are subjected to electrophoresis in various types of gels and subsequently submersed in solutions containing enzyme-specific stains. Genetic analysis may indicate that some of the variant electromorphs are encoded by alternate alleles at a single locus, in which case the allelic products are termed allozymes (Prakash et al., 1969). Data retrieved from electrophoretic gels consist of the number and relative mobilities of various enzyme products, which with appropriate genetic analyses become transformed into single or multilocus genotypes for each individual analyzed. Reasons are many for the popularity of electrophoretic data (Avise, 1975; Gottlieb, 1977; Crawford, 1983), but foremost among these is that isozymes provide a series of readily scored, single-gene markers.