In vitro induction of adventitious shoot and embryo formation in somatic tissues of apple (Malus pumila Mill.) zygotic embryos and stem segments

Abstract

Somatic tissue of embryo origin represents a good source for adventitious regeneration to study somaclonal variation, mutation breeding, gene transfer, etc. Seed sections (cotyledon and hypocotyl segments) of in vitro stratified immature zygotic embryos and internodal stem segments of four-week-old in vitro grown seedlings of open pollinated apple cultivar Vista Bella and of controlled pollinated Vista Bella × Prima, Vista Bella × Liberty were used. The effects of type and concentration of mineral, organic and growth regulator components of culture media and its pH value on regenerative capacity of apple embryonic tissues were studied. The highest rate of shoot formation was obtained by hypocotyl segments cultured on MS (Murashige & Skoog 1962) medium containing benzylaminopurine (BA) 2 mg/1 and naphtaleneacetic acid (NAA) lmg/l at pH 5.2 prior to autoclaving. Up to 48% of cotyledon sections and 63% of internodal stem segments produced adventitious somatic embryos when cultured on SC (Skirvin & Chu 1977) medium supplemented with BA 2mg/l, NAA 0.5 mg/1 and GA3 0.1 mg/1 filter sterilized at pH 5.8. Somatic embryos developed into normal plants only after being stored for 5 to 7 weeks at 4 °C.