NISCAIR Online Periodicals Repository Collection: IJBT Vol.03(2) [April 2004]

Biotechnological interventions for genetic amelioration of Actinidia deliciosa var. deliciosa (kiwifruit) plant

Title: Biotechnological interventions for genetic amelioration of Actinidia deliciosa var. deliciosa (kiwifruit) plant

Authors: Sharma, D R; Shirkot, Poonam

Abstract: Kiwifruit (Actinidia deliciosa var deliciosa) is a recent introduction among the promising fruit crops. Popularity of its nutritious fruit berries has created a substantial demand for quality planting material, which needs to be planted in certain proportions of female and male plants for Actinidia is dioecious. The large-scale propagation of planting material can be achieved through micropropagation; whereas, it's quality and clonal nature need to be ensured, preferably, through molecular markers. With further popularity of this fruit crop, tailor-made genotypes will be required, which can be made possible through biotechnological interventions. As A. deliciosa is limited in its adaptation to a very narrow range of agroclimatic conditions, there is also a need to develop cultivars endowed with traits of wider adaptation. So that this fruit crop can be cultivated in larger range of geographical areas. Development of micropropagation protocols, identification of gender at seedling stage, identification of molecular markers to test genetic/clonal fidelity and incorporation of genes for genetic amelioration are the issues that need immediate consideration. Some of these issues have been addressed in the present paper.

Page(s): 249-257

Tobacco (Nicotiana tabacum L.)-A model system for tissue culture interventions and genetic engineering

Title: Tobacco (Nicotiana tabacum L.)-A model system for tissue culture interventions and genetic engineering

Authors: Ganapathi, T R; Suprasanna, P; Rao, P S; Bapat, V A

Abstract: Tobacco (Nicotiana tabacum L.) has become a model system for tissue culture and genetic engineering over the past several decades and continues to remain the 'Cinderella of Plant Biotechnology', An ill vitro culture medium (Murashige and Skoog, 1962), based on the studies with tobacco tissue cultures, has now been widely used as culture medium formulation for hundreds of plant species. Studies with tobacco tissue culture have shed light on the control of in vitro growth and differentiation. Further, induction of haploids, microspore derived embryos and selection of mutant cell lines, have been achieved successfully. Tobacco has also been employed for the culture and fusion of plant protoplasts, providing invaluable information on way to explore the potential of somatic hybridization in other crops. Optimization of genetic transformation, using Agrobacterium tumefaciens and A. rhizogenes, has been central to the cascade of advances in the area of transgenic plants. Developments in the field of molecular farming for the expression and/or production of recombinant proteins, vaccines and antibodies are gaining significance for industrial use and human healthcare.

Page(s): 171-184

Induced nucellar embryogenesis in vitro for clonal multiplication of Mangifera indica L. var. Ambalavi: A dwarfing rootstock

Title: Induced nucellar embryogenesis in vitro for clonal multiplication of Mangifera indica L. var. Ambalavi: A dwarfing rootstock

Authors: Chaturvedi, H C; Agnihotri, S; Sharma, M; Sharma, A K; Jain, M; Gupta, P; Chourasia, A; Kidwai, N R

Abstract: Nucellar embryogenesis was induced in Mangifera indica L. var. Ambalavi, a monoembryonic dwarfing rootstock. Nucellar tissue of young fruits of 3 developmental stages and measuring about. 2.5, 4 and 5 cm in length, responded differently to the same treatments of agarified nutrient medium used for induction of embryogenesis. Whilst 0.25 mg l^-l BAP along with 1 mg l^-l NAA was effective to induce embryogenesis in nucellus of youngest fruits, 0.5 mg l^-1 2iP alone was sufficient for nucellus of older fruits. However, all the differentiated embryos proliferated in a single treatment comprising 0.15 mg l^-1each of BAP and 2iP and 0.5 mg l^-l IAA, albeit with a different basal medium. Size of cotyledonary nucellar embryos ranging between 1.5 to 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 l^-1 ABA, 0.1 mg l^-1 IAA and 100 mg l^-1 PEG (M. Wt. 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., about. 70% than those with their initial root system, where it was about. 50%. The former also survived longer than the latter, i.e., beyond 4 months.

Page(s): 221-228

Polyamine-ethylene nexus: A potential target for post-harvest biotechnology

Title: Polyamine-ethylene nexus: A potential target for post-harvest biotechnology

Authors: Kumar, S Vinod; Rajam, M V

Abstract: Post-harvest biotechnology is a fast growing field of plant biotechnology. Achievements were made in the field to delay or prevent fruit ripening and softening by genetic manipulation of ethylene and cell wall metabolism. Despite the development of transgenic plants with the desired traits, the technology has not achieved the pace due to drawbacks of the existing strategies to effectively control the developmental processes following harvest. Here the authors analyse various strategies of post-harvest biotechnology and prospects, giving special emphasis to the metabolic interactions of pathways related to post-harvest characteristics-- those of polyamine and ethylene-- and the engineering of polyamine metabolism as an alternate strategy for post-harvest biotechnology by carefully manipulating the delicate metabolic balance and the benefits of the newly proposed strategy over the currently used ones.

Page(s): 299-304