Vol. 74 No: 1

Title:
Somatic embryogenesis and plantlet regeneration from nucellar tissue of monoembryonic mango

Author:
PIOUS THOMAS

pp: 135-139

Abstract:
In hydroponically grown stock plants, growth was reduced by 7 d stress treatments with NaCl at concentrations of 2, 4 or 6 l^-1. The uptake of other ions (except Mg) was unaffected. Rooting of cuttings from the stressed plants was depressed, with a 45% decrease in root numbers, almost 70% in root length and 52% for root weights. This drastic effect on the rooting was overcome after two weeks of postpropagation growth, when the cuttings had recovHigh frequency somatic embryogenesis from nucellar explants was achieved in the monoembryonic mango 'Arka Anmol'. For culture initiation, immature fruits of 2-3 cm long about 30-40 d post-pollination were ideal. Culturing half ovules with intact nucellus gave better percentage callusing and more embryonic cultures than using excised nucellus. Among the basal media, Rugini olive (RO) medium followed by Gamborg's B5 (B5) was superior to the Murashige and Skoog (MS) medium for culture establishment and embryo induction. However, B5 medium was better than the others for embryo conversion and further development. Embryonic calli formed on establishment medium (RO, 6% sucrose, 2 l^-1 activated charcoal [AC], 2 l^-1 phytagel, 5 ml^-1 each of 2,4-D and GA₃) on transfer at 2-3 weeks to expression medium (RO with 6% sucrose, 2 l^-1 AC, 2 l^-1 phytagel, 400 mg-1 glutamine [Gl], 1-3 ml^-1 2,4-D and 10 ml^-1 GA₃) showed pro- and globular embryos in another 2-3 weeks. Further embryo development through heart and early cotyledonary stages occurred in a conversion medium (half strength B5 salts, full RO organics, 4% sucrose, 400 ml^-1 Gl, 2 l^-1 phytagel, 2 l^-1 AC, 100 ml^-1 casein hydrolysate, 20% [v/v] coconut water, 0.5 ml^-1 2,4-D and 10 ml^-1 GA₃). Proliferating embryonic cultures could be maintained in this conversion medium giving a continuous supply of embryos. Embryo maturation was obtained in the presence of 1 ml^-1 abscisic acid. Germination with shoot and root development was obtained in presence of 0.01 to 0.1 ml^-1 thidiazuron. Partly senescent fruits about to drop or having just fallen could also be used as the source of embryonic cultures. Preliminary studies using other monoembryonic cultivars revealed genotype dependent differential responses.ered, except for those from the highest salt stress treatment.

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