Rangaswamy (1968) refers to nucellus cultures of several cucurbits (Coccinea, Cucumis, Luff a, Trichosanthes) on 62 media, involving 12 supplements in 20 combinations.
Possibilities that exist for present research
Recent progress in the field of cell and tissue culture has made this area of research as one of the most valid and promising one in experimental biology. In vitro cultures are now being used as tools for the various basic problems not only in the plant physiology and cell biology and genetics but also in agriculture, horticulture and industry. Cell and tissue culture have enabled us to increase our knowledge in many areas including totipotency, cell differentiation, cell division, cell metabolism, radio-biology and cell preservation. We are now able to cultivate cells as clones from single cells to grow plants, from isolated meristems to induce callus and from single cells to develop into complete plants, either by organogenesis or directly by embryogenesis in vitro. It is also possible to attain plants of various levels of ploidy, by tissue and endosperm culture and to produce haploids by using embryo culture techniques, after interspecific hybridization followed by chromosomal elimination of one of the parents. It is also possible to propagate plants of economic importance, such as orchids and other ornamentals in large numbers by meristem culture, or by other in vitro methods; and by this means they can be made free from viruses. Apart from that, in plant breeding programmes, embryo culture, ovary culture and ovule culture as well as in vitro pollination have been employed to overcome sterility and incompatibility.
Anther culture plays an important role in the production of haploids. Haploid plants are important to genetics because mutants can be easily recognised and homozygous plants can be obtained directly within a single generation. By anther culture, it is possible to produce haploids in large number from more than 20 species.
Another important aspect in this field of research is the protoplast culture. Protoplast of higher plants cells are potentially of equal importance as tools for genetic engineering and somatic hybridization. They can be produced in large numbers by enzyme treatment. They can be cultured: They will regenerate cell wall, divide and develop into haploid or diploid plants. Under appropriate conditions, they fuse and the fusion products can be cultured and even regeneration of somatic hybrids has been recently reported.
Protoplast can also take up genetic material in the nuclei, chloroplast as well as isolated DNA molecules. This provides opportunity to combine the genotypes of species which are sexually incompatible and to introduce foreign genetic material such as organelles or DNA into the genome, since the cultures of haploids and protoplasts can be manipulated by using the methods of microbial genetics. It is understood that the new developments have attracted the attention of geneticists and plant breeders.
