its a cytology presentation

1. MAINTENANCE OF
CYTOGENETIC STOCKS AND
THEIR IMPORTANCE

2. Genetic stocks are lines that contain various
mutant alleles, chromosomal rearrangements, or
other cytological abnormalities that are useful
only for genetic and basic biological experiment.
Genetic stocks

3. OTHER CLASSES OF ORGANISMS
• Coliform bacterium Escherichia coli
• Pink bread mold Neurospora crassa
• Fruit fly Drosophila melanogaster
 They have no direct economic benefit but that are used
solely for the purposes of research and teaching .

4. Genetic stocks can be divided into three general groups:
Cytological stocks (e.g. chromosome addition/substitution, aneuploids)
Mutants (e.g induced/insertion mutants, tilling populations)
Germplasm sets (e.g. mapping populations, parental lines, reference
germplasm)

5. Cytogenetic Stock
Cytogenetic stocks are desired chromosome , aneuploidy lines
that are useful for genetic and basic biological experiment.
 Variants with different chromosome structures.
 Variants in chromosome number.
 Alien and substitution lines.

6. With Different chromosome structures.
Due to..
Deletion Duplication
Inversion

7.  translocation of specific DNA segments from one
chromosome to another
 They are important in gene mapping,
determination of the chromosomal location of
specific genes, and studies of chromosome
structure and function.

8. variants in chromosome number
 These may include..
 changes in whole genomes of plants(haploids or polyploids)

9.  changes in the number of a single chromosome,
chromosome arm, or chromosome segments (nullisomics,
monosomics, telosomics, trisomics, or tetrasomics).
 Such variants are also valuable in genetic mapping and in
basic genetic studies, such as in the study of genetic
architecture of chromosomes.

10. Alien and substitution lines
 The wild and the weedy relatives of the major crops are
sometimes used as germplasm sources in breeding programs.
 A first steps is often the transfer of individuals chromosomes
or chromosome segments, carrying identified genes of
potential economic importance into the crop species.
 The types of alien chromosome segments used to transfer the
desired gene into commercial crop varieties are addition lines,
and translocation lines.

11. Aneuploidy
 Is a second major category of chromosome mutations in which
chromosome number is abnormal.
 An aneuploid is an individual organism whose chromosome
number differs from the wild type by part of a chromosome set .
 Nullisomics (2n − 2)
 Monosomics (2n − 1)
 Trisomics (2n + 1)

12. A) ADDITIONS TO
CHROMOSOME NUMBER:
 Trisomy [2n + 1]: examples in humans include Klinefelters
(XXY), and Down’s syndrome individuals [2n = 47D].
 Tetrasomy [2n + 2]: examples are mostly in polyploid plants

13. B) REDUCTIONS IN
CHROMOSOME NUMBER:
 Monosomy [2n – 1]: example in humans is Turners (XO).

14. Nullisomics (2n − 2)
 Nullisomy is a lethal condition in diploids, an organism
such as bread wheat, which behaves meiotically like
a diploid although it is a hexaploid, can tolerate nullisomy.

15. TRISOMICS (2N + 1)
 The trisomic condition also is one of chromosomal imbalance and
can result in abnormality or death.
 Klinefelter syndrome (XXY)

16. IMPORTANCE AND USE OF GENETIC
STOCK COLLECTIONS
1) To conserve both
 Economically important species, corn (Zea mays) and yeasts
(Saccharomyces sp.).
 Organisms used purely for research such as fruit flies
(Drosophila sp.) & bread molds (Neurospora sp.).
2) Used in mapping the genes.
3) Can preserve stocks for many years.

17. 4) Helps in the identification, location, and isolation of specific
genes and their manipulation and transfer into economically
important plants and animals for breeding programs using
molecular genetics tools.
5) Its helps in conserving endangered species.
6)These are used solely for genetic research and teaching.
7) Used for new hybrid production.

18. USE OF CYTOGENETIC STOCK COLLECTIONS
 Used to determine the phenotypic effects of loss or
gain of different chromosomes.
 Used to produce chromosomal substitution lines.
 Find the location of genes as well as of a linkage
group onto a specific chromosome.
 To Establish homoeology (by to study of nullisomic)
 Used to identify the chromosomes ivolved in
translocation.
 Used to prepare molecular maps.

19. MAINTAINING GENETIC (or)
CYTOGENETIC STOCK
It requires
 Technical labours
 Scientific inputs
 Mechanised Tools
 Resources
The broad requirements include the following:
 Suitable low-temperature, low-humidity facilities;
 Access to back-up storage facilities;
 Adequate seed-handling facilities for drying, cleaning,
packaging, and viability testing of seed samples; and
 Computerized information storage and retrieval systems.

20. Special Needs and Requirements
 Genetic stocks require highly specialized knowledge,
procedures, and care for adequate regeneration and
maintenance.
 Albino mutants are one obvious example. Some stocks may
not routinely survive in the field and need to be grown in a
greenhouse, whereas others may need special treatments (long
days or vernalizing temperatures) before they flower or may
require genetic or cytological screening.
 Genetic stock collections are difficult, and sometimes
impossible, to maintain as part of national or international
germplasm collections.

21. EXAMPLES OF GENETIC STOCK
COLLECTIONS
The Charles M. Rick
Tomato Genetics
Resource Center
Barley Genetic Stock
Collections
The Barley Genetic
and Aneuploid Stock
Collection

22. The Charles M. Rick Tomato Genetics
Resource Center
 Tomato Genetics Stock Center (TGSC)
 Charles M. Rick of the Department of Vegetable Crops at the
University of California, Davis
 Davis is near the center of the largest tomato-growing area in
the world, and in 1987 nearly one-quarter of the world's
processing tomatoes were grown in eight counties within a
129-km radius of Davis.

23. Barley Genetic Stock Collections
 Barley geneticists and breeders
 Under this scheme, individuals are appointed to coordinate
maintenance of each of the different categories of genetic
and chromosomal variants commonly found in barley.
 coordinators have been appointed for maintaining genetic
stocks.

24. The Barley Genetic and Aneuploid
Stock Collection
 Barley Genetic and Aneuploid Stock Collection (BGASC)
 was established by D. W. Robertson in the Agronomy
Department at the Colorado State University, Ft. Collins
 for genetic linkage studies in barley. These studies began in
the 1920s and emphasized simple morphologic marker
genes of value in early linkage studies
 Over the years the collection was enriched by the addition of
a wide range of naturally and artificially generated variants,
linkage testers, and more recently, of cytogenetic stocks
from the local program and others in the United States.