BIOTECHNOLOGY - Inshyna N.M. - 2009

CHAPTER 3. CELL ENGINEERING

Haploid Cell Cultures

Haploid Cell cultures are widely used in plant breeding. Haploid plants, which possess the chromosome set characteristic of Gametes, are derived from haploid Cells. Homozygous plants are utilized to investigate Gene interactions, study genetic Variability, and perform quantitative genetic analysis. All Mutations become apparent in such plants because recessive mutations are not masked by dominant alleles. Homozygous plants are devoid of lethal or sublethal mutations.

Through colchicine-induced polyploidization, haploids can also yield homozygous diploids that ensure the stable expression of traits across many generations. Homozygous lines are applied in breeding for heterosis.

Haploids are obtained through two main Methods:

1) in vitro cultivation: entire plants can be regenerated from unfertilized Germ Cells with a reduced chromosome set. Haploids produced in this manner are sterile;

2) distant Hybridization (Chromosomes of one of the species are eliminated within the hybrid zygote).

Haploids of higher plants are predominantly derived from the sporogenous tissue cells of anthers (gametophyte). Haploid plants were first successfully obtained in 1964 by Indian scientists S. Guha and S. Maheshwari during the in vitro culture of Datura anthers. Since then, over 200 species of haploid plants have been produced, including wheat, barley, rye, rice, and potato. By 1984, 40 plant species had been cultivated from anther cells in China, resulting in The Development of short-stemmed, high-yielding rice varieties.

During distant hybridization of certain species, The phenomenon of selective chromosome elimination has been observed at Cytology/cytology/16.html">Early stages of hybrid embryo development. For instance, crossing the cultivated barley Hordeum vulgare with the wild species Hordeum bulbosum results in the loss of the wild species' chromosomes, yielding a haploid containing the chromosome set of the cultivated species. This method has been successfully used to develop the Istok and Odeskyi-115 barley varieties.