A Technique for Somatic Chromosome Preparation and C-banding of Maize

Abstract

Cytogenetic studies of both plants and animals have been considerably enhanced by differential staining techniques developed since the pioneering studies of Casperson et al. with fluorescent stains (1968, 1969a,b). The first non-fluorescent banding technique (employing the Giemsa stain) was developed by Pardue and Gall (1970). The Giemsa stain has an obvious advantage over fluorescent stains in that the researcher can utilize ordinary light microscopy and permanent preparations. Many researchers have applied chromosome banding techniques in research on maize and its wild relatives (Horn and Waiden 1971; Vosa and Marchi 1972; Hadlaczky and Kaiman 1975; Sachan and Tanaka 1976; Ward 1980; Mastenbroek and de Wet 1983; Aguiar-Perecin and Vosa 1985; Bernard and Jewell 1985; Gu et al. 1985; Laurie and Bennett 1985; Rayburn et al. 1985; Kakeda et al. 1990; Porter and Rayburn 1990). In brief, these studies have shown that heterochromatin patterns observed in pachytene chromosomes of maize can be detected in mitotic chromosomes by C-banding. In other preparations, the knobs on the maize chromosomes are not visible at mitotic metaphase where the chromosomes have been estimated to be approximately 13 × shorter than at meiotic midpachynema (Filion and Waiden 1973). The C-banding technique of mitotic chromosomes apparently detects the heterochromatin present in the knobs visible at pachynema in meiosis; the knobs contain a highly repeated 185-bp DNA sequence (Peacock et al. 1981). The C-banding technique has proved useful for chromosome characterization and identification because the C-banding patterns are heritable and remain discernible throughout the mitotic and meiotic cell cycles.