Technology of storage and primary processing of agricultural products

The reaction of the cell under the influence of various rays
Irradiation of the cell under the influence of various rays creates profound changes in its composition. Therefore, critical and lethal doses of radiation are different . The effect of light also depends on the state of the organism during the irradiation period, the humidity of the affected material, the temperature and the intensity of the light. For example: the critical dose for sprouted cotton seedlings is 1 kr (kilo x-ray), 0.5-2 kr for plants during flowering and flowering, 600-800 x-rays for pollen grains.
Normally, cotton seeds are exposed to light to form a mutation. Changes in cell division (mitosis) during germination of irradiated seeds can be observed under a microscope . These changes can be in the form of chromosome aberrations and changes in their number , gene mutations, or changes in genetic material . To observe mitotic division after irradiation, the seed is collected on a Petri dish and a permanent or temporary drug is prepared from the roots . Chromosome aberration can be clearly seen during anaphase and telophase of mitosis . Typically, during the anaphase of mitosis , the chromatids are evenly distributed at the poles, and the number of chromosomes (2n) in the new daughter cells is equal to that of the original mother cell.

17- LABORATORY WORK.

Topic: The phenomenon of polyploidy

The purpose of the work. It consists of studying the differences that occur in traits with changes in chromosomes in the body.
The content of the work. Each plant and animal species has a certain number of chromosomes . The number of chromosomes can change as a result of disruption of cell division . A multiple increase in the number of haploids on a chromosome is called a polyploidy. Polyploidy is a major source of variability for selection work and the evolutionary process. A group of species belonging to the same genus can form a polyploid series. Some plant species have formed very long polyploid rows. For example, chromosomes 14, 21, 28, 35, 42, and 56 are known in the Rosa family, and chromosomes 26 and 52 are known in the Gossypium family.
The minimum number of chromosomes in a polyploid array is denoted by an “x” and is called the base number. X * 7 in the Rosa lineage and x * 13 in the Gossypium lineage. The set of genes on hyploid chromosomes is called the genome. Formed the basis of the increase in the genome of the same poliploidlar increase in the genomes of various avtopoliploidlar formed on the basis of poliploidlar allopoliploidlar said.
For example: wheat genome I, diploid II, autotriploid III, autotetraploid IV, autopentoploid V and so on.
When hybrids of different species are mixed, 2 species genomes are added to the hybrid . Often such hybrids are F ₁ generation offspring. To overcome infertility, it is necessary to double the total number of chromosomes to form an allopolyploid (amphidiploid).
For example: G. hirsutum (2n * 52) AD genome J. herbaceum (2p-26) When the A genome is mixed, 39 chromosomes (allotetraploid) AAD genome are formed in the somatic cell of F ₁ hybrids .
These hybrids standards division is broken: G. harbaceum in 13 large chromosome G. hirsutum 13 large chromosomes konyugatsiyalanadi, but G. hirsutum in May 13 chromosomes univalent case. Such hybrids form a sterile (void) powder. To overcome sterility, chromosomes need to be doubled. The result is the allotetraploid 2p-78 (AAAADD) genome, in which all its chromosomes in meiosis have their own homologous pairs.
An increase in the number of chromosomes can alter some morphological traits and biological characteristics in a plant . Compared to diploid defects, tetraploid plants are distinguished by a blue (vegetative) mass, high seed weight and large flowers. Polyploid plant cells, pollen tubes, mouthparts on the leaf blade become larger, and their diameter also increases.