Isozyme Analysis Procedures for Stone Fruits, Almond, Grape, Walnut, Pistachio, and Fig

Abstract

Abstract Applications of gel electrophoresis and isozyme analysis to horticultural science were outlined more than a decade ago by Peirce and Brewbaker (15). Isozymes now are being widely used in almost all areas of plant biology, including plant breeding, plant population genetics, systematics, evolutionary genetics, and somatic cell genetics. Isozymes offer the most reliable single gene markers and they are often codominant in inheritance. Genetic studies using isozymes in tree fruit and nut crops are few. Torres and Tisserat (26) reported single gene markers using isozymes in date palm, Arulsekar et al. (4) in strawberry, Torres et al. (23) in avocado, and Arulsekar et al. (1, 3) in walnuts; perhaps the only reliable gene markers available for breeders of these crops. Torres et al. (24) have also reported isozyme genetic markers in Citrus and demonstrated their use in distinguishing nucellar seedlings from those of zygotic origin. Ben-Hayyim et al. (5) developed isozyme systems that will facilitate identification of interspecific cell hybrids and fusion products in Citrus. Arulsekar et al. (3) studied glucose phosphate isomerase (GPI) and aspartate aminotransferase (AAT) isozymes in callus tissues, juvenile leaves, and adult leaves of walnuts using the same enzyme extraction procedure and found no tissue-specific differences in isozyme patterns. McGranahan et al. (11) used isozymes to identify intergeneric hybrids generated between wingnut (Pterocarya sp.) and walnut (Juglans sp.). Parfitt et al. (13) demonstrated the use of isozymes in the identification of interspecific hybrids between peach and plum cultivars. The inheritance of MDH isozymes in peach was reported by Arulsekar et al. (2). Among 298 peach cultivars tested, variation was observed only for malate dehydrogenase (MDH) isozymes. The MDH isozymes were used by Parfitt and Miller (unpublished data) to study outcrossing rates among peach cultivars.