In this article we will discuss about the process of androgenesis, explained with the Success of anther culture is highly dependent on the genotype of the plant. The success of androgenesis dependent on the variety used, the growth . Razdan M.K, An introduction to plant tissue culture, ().Oxford. In vitro androgenesis is an important component of plant biotechnology when the pollen .. In: Korea-China Plant Tissue Culture Symposium, Academia Sinica.
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Microspores undergoes division in unorganised fashion to give rise to callus and by embryogenic or organogenic induction the haploid plantlets may be obtained. The uninucleate microspores divide unequally forming vegetative and generative cell. Haploid plants are obtained either by androgenesis or andogenesis.
The basic principle of native plannt is to stop the conversion of pollen cell into a gamete, and force its development into a plant. There are two approaches in androgenesis— anther culture and pollen microspore culture.
This technique was later applied for raising haploid plants of rice, wheat, maize, sunflower, sugar beet and tobacco. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes.
The uninucleate microspore undergoes equal division to form two daughter androgfnesis of equal size e. In contrast, there are a large number of microspores in one another. Anthers at a very young stage with microspore mother cells or tetrads and late stage with bi-nucleate microspores are usually not suitable for androgenesis.
Flowers obtained from young plants, at the beginning of the flowering season are highly responsive. The haploid cells, in general, are unstable in culture with a tendency to undergo endomitosis.
Injured anthers should not be used in cultures as they result in callusing of anther wall tissue.
As soon as the starch deposition starts within the microspore there is no further development towards sporophyte. The pollen suspension is filtered to remove anther tissue debris. This stimulates the axillary buds to grow into diploid and fertile branches. The procedure involves growing a small segment of haploid plant stem in a suitable medium supplemented with growth regulators auxin and cytokinin. Two approaches based on morphology and genetics are commonly used to detect or identify haploids.
This results in homozygous plants. The anther should be collected from the flower buds of adult healthy plant and it is very important to use the healthy explant.
After removal of calyx, corolla and stamens, the ovaries androggenesis Fig.
Several markers are in use. There are many ways of colchicine treatment to achieve diploidization for production of homozygous plants.
After formation of macroscopic structures, these can be transferred to a regeneration medium and kept at 14 hr. As the cells divide, the pollen grain becomes multicellular and burst open. The disadvantages associated with anther culture can be overcome by pollen culture. The Indian scientists Cuha and Maheswari reported the direct development of haploid embryos and plantlets from microspores of Datura innoxia by the cultures of excised anthers.
The plants so produced are referred to as gynogenic haploids. In certain plants, the microspore divides unequally to give bigger vegetative cell and a smaller generative cell. Further, induction of androgenesis is better if anthers are stored at low temperature, prior to culture culturr. Certain chemicals are known to induce culgure e.
Production of Haploid Plants (With Diagram)
If they are at the tossue stage, each anther is gently separated from the filament and the intact anthers are inoculated on a nutrient medium. Haploid production occurs through anther or pollen culture, and they are referred to as androgenic haploids. Anther culture is easy, quick and practicable. Endomitosis is the phenomenon of doubling the number of chromosomes without division of the nucleus.
The variation in response of anthers from plants grown under different environmental conditions may be due to the differences in endogenous level of growth regulators.
This variation may be due to endomitosis or fusion of culthre nuclei during the developmental stages of anthers at the time of excision and culture.
Production of Haploid Plants (With Diagram)
The vegetative and floral parts and tisssue cell sizes of haploid plants are relatively reduced when compared to diploid plants. The above markers anrrogenesis been used for the development of haploids of maize. Plant breeders have been conducting extensive research to develop haploids. This induces callus formation followed by differentiation. This multicellular mass may form a callus which later differentiates into a plant through callus phase.
Subsequently, Bourgin and Hitsch obtained the first full-pledged haploid plants from Nicotiana tabacum. Ultra violet rays or X-rays may be used to induce chromosomal breakage and their subsequent elimination to produce haploids.