In Vitro Factors During Ovule Culture Affect Development and Conversion of Immature Peach and Nectarine Embryos

Abstract

Various in vitro conditions for culture of ovules prior to extraction and culture of immature embryos of peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica (L.) Batsch var. nucipersica Schneid.] were investigated. Culture vessels consisting of test tubes, petri dishes, and polycarbonate jars were tested along with various types of support and nutrient media. Agar support was superior to liquid media with filter paper supports. Agar produced the largest embryos with 90% to 93% being converted into plants compared to liquid with only 1% to 12% embryo conversion. The best ovule orientation and support was with the micropyle down and pushed halfway into an agar-gelled medium. In experiments two and three, test tubes with vertical ovule orientation (micropyle end of ovule pushed into agar) produced larger embryos, the largest plants and the greatest percentage of embryos that converted into plants (60% and 91%). Petri dish treatments were less successful in embryo conversion than test tubes and polycarbonate jars. The addition of activated charcoal (AC) to an agar-gelled medium produced significantly larger embryos with a similar conversion rate. The addition of an agar-gelled medium to culture vessels reduces preparation time compared to filter paper supports, and placing each ovule within a test tube eliminates cross contamination, making immature embryo culture more successful.