EMBRYO CULTURE AND GEL-ELECTROPHORETIC IDENTIFICATION OF NUCELLAR AND ZYGOTIC SEEDLINGS OF CITRUS-LIMON (L) AND CITRUS-SINENSIS (L)

Five enzyme systems: peroxidase, esterase, glutamate oxaloacetate transaminase, malate dehydrogenase and malic were assayed in Citrus limon (rough lemon) and Citrus sinensis (Valencia) by polyacrylamide gel electrophoresis. Isozyme profiles were used to distinguish nucellar from zygotic seedlings produced from in vitro culture of preformed embryos. The frequency of zygotic seedlings resulting from open-pollination varied between 0.0% and 9.0%. Embryo culture significantly enhanced the recovery of zygotic seedlings in Rough lemon but not in Valencia. Plantlets produced via in vitro nucellar embryogenesis were genetically uniform. The isolation and culture of preformed embryos resulted in the production of up to 13 and 9 seedlings per seed in Valencia and Rough lemon, respectively. The use of tissue culture and isozymes as tools in citrus breeding is discussed.