Variation of plants derived from indirect somaticembryogenesis in cotyledon explants of papaya

摘要

Somatic embryogenesis in papaya (Carica papaya) cv. Kaekdum was induced from embryogenic callusderived from cotyledon explants by culturing on modified half-strength MS basal medium supplemented with 15 mg/1 2,4-dichlorophenoxyacetic acid (2,4-D), 400 mg/1 glutamine, 80 mg/1 adenine sulphate, 170 mg/1 NaH)_2PO4_4 H_2O, 15% (w/v)coconut water, and 60 g/1 (w/v) sucrose. The somatic embryos were grown on modified half-strength MS basal mediumsupplemented with 2 mg/1 2,4-D and 60 g/1 sucrose. Upon transferring to MS basal medium, somatic embryo germinationand plantlet conversion were observed. Variations at the morphological and molecular level were examined in the somaticembryo-derived plants which, after acclimatization, were grown under field conditions. Three types of primers (S-02, S-03,and S-07) were used for random amplified polymorphic DNA analysis. The results from DNA fingerprints revealed bothmonomorphic and polymorphic bands with sizes ranging from approximately 190-7120, 120-4990, and 280-3600 basepairs, respectively. The size differences might be related to morphological variations observed in the field-grown papayaplants derived from somatic embryogenesis. These morphological variations include plant height, number of flowers, florallength, number of fruits, fruit dimension, and fruit shape. Since these plants produced only hermaphrodite flowers, it islikely that the somaclonal variation could occur in field-grown papaya plants derived from indirect somatic embryogenesis.