Induced nucellar embryogenesis in vitro for clonal multiplication of Mangifera indica L. var. Ambalavi: a dwarfing rootstock.
Chaturvedi H. C., Agnihotri S., Sharma M., Sharma A. K., Jain M., Gupta P., Chourasia A., Kidwai N. R.
Author Affiliation: Tissue Culture Laboratory, National Botanical Research Institute, Lucknow 226 001, India.
Indian Journal of Biotechnology 3 : 221-228
Abstract : Nucellar embryogenesis was induced in M. indica cv. Ambalavi, a monoembryonic dwarfing rootstock. Nucellar tissue of young fruits of 3 developmental stages and measuring ~2.5, 4.0 and 5.0 cm in length, responded differently to the same treatments of agarified nutrient medium used for embryogenesis induction. Whilst 0.25 mg BAP [benzyladenine]/litre along with 1 mg NAA/litre was effective to induce embryogenesis in nucellus of youngest fruits, 0.5 mg 2iP [isopentenyladenine]/litre alone was sufficient for nucellus of older fruits. However, all the differentiated embryos proliferated in a single treatment comprising 0.15 mg/litre each of BAP and 2iP and 0.5 mg IAA/litre, albeit with a different basal medium. Size of cotyledonary nucellar embryos ranging between 1.5 and 2 cm in length was necessary for their further development, maturation, germination (visible plumule and developed root) and convertibility (plantlet formation). Embryos of desirable size required the liquid state of the medium supplemented with 0.01 mg ABA/litre, 0.1 mg IAA/litre and 100 mg PEG/litre (MW=400), while the nitrogen content was also low for their near-synchronized development, maturation, germination and convertibility. In the optimum treatment, most of the embryos showed apparently normal development, of which, 78.4% matured and 40.2% germinated, while 35.6% embryos produced plantlets. Such a high percentage of convertibility of nucellar embryos has not been obtained earlier. The hardened in vitro-raised plantlets survived ex vitro when first transplanted to Soilrite followed by their transfer to the garden soil. Furthermore, adventitiously rooted nucellar plantlets gave better transplant success, i.e. ~70% than those with their initial root system, where it was ~50%. The former also survived longer than the latter, i.e. beyond 4 months.