In%20Vitro%20Selection - PowerPoint PPT Presentation

About This Presentation
Title:

In%20Vitro%20Selection

Description:

... NaCl Drought tolerance PEG Mannitol ... between the mechanism of tolerance operating in the culture and those of the whole plants Phenomenon of ... – PowerPoint PPT presentation

Number of Views:113
Avg rating:3.0/5.0
Slides: 13
Provided by: ToddA152
Category:

less

Transcript and Presenter's Notes

Title: In%20Vitro%20Selection


1
In Vitro Selection
Screen a large number of plants or cells for a
certain characteristics
2
Definition Selection vs. Screening
  • Selection
  • The process by which some individuals come to
    contribute more offspring than others to form the
    next generation through intrinsic difference in
    survival and fertility or the choice of parent by
    the breeder
  • The process determining the relative share
    allotted individuals of different genotype in the
    propagation of a population
  • The process by which certain organisms multiply
    while other are less suited surrounding and die
    out

3
Definition Selection vs. Screening
  • Screening
  • An investigation of a large number of organisms
    for the presence of a particular property
  • Use of a screen
  • Examining the properties, performance response of
    individuals, lines, genotypes or other taxa under
    an assortment of condition in order to evaluate
    the individuals or groups

4
Selection
  1. The central step of the breeding process
  2. The success depends on the ease and speed with
    which the superior plant within a segregating
    population can be identified
  3. In classical breeding, selection is carried out
    on huge populations normally in the fields
  4. Field selections are strongly influenced by
    environmental condition
  5. There are uncertain and lengthy, especially in
    the case of breeding for quantitative
    characteristics with a polygenic background

5
Selection methods
  • The most common breeding procedure was
    mass-selection which in turn was subdivided into
    negative and positive
  • Negative selection
  • The most primitive and least widely used method
    which can lead to improvement only in exceptional
    cases
  • implies culling out of all poorly developed and
    less productive individuals in a population whose
    productivity is to be genetically improved
  • The remaining best individuals are propagated as
    much as necessary
  • Positive selection
  • Only individuals with characters satisfying the
    breeders are selected from population to be used
    as parents of the next generation
  • seed from selected individuals are mixed, then
    progenies are grown together

6
Selection
  • On the whole plant
  • Field trials
  • Green-house trials
  • Laboratory trials (in vitro selection)
  • 2. On the simple genome (in vitro selection)
  • Haploid selection
  • Single cell selection
  • DNA probes

7
Target of In vitro Selection
Whole plant (Seed/embryo)
1. Seedlings of a culture filtrate from Leptosphaeria masculans (disease resistance) 2. Rice seedlings of salt enrichment media (Mineral tolerance)
1. Leaf segment of young barley with standardized spore of powdery mildew (disease resistance) 2. Petiole culture of sugarbeet on salt enrichment media (mineral tolerance)
Selection of somaclonal variation (disease resistance, environmental tolerance) Selection using a selective agent (disease resistance, salt tolerance, metals tolerance, temperature stress tolerance, herbicide tolerance)
1. Selection for biotic stress resistance 2. Selection for a-biotic stress tolerance (cold, heavy metals, herbicide)
Quantitative trait loci Marker assisted Selection Marker assisted backcrossing
Organ
Tissue
Single Cells
DNA
8
In vitro selection to heterogenous population
Screen large number of plant or cells for a
certain characteristics in sterile artificial
medium
  • Certain characteristics
  • Biotic stress resistance
  • A-biotic stress tolerance

Applying selection agent (screening)
9
Screening Agent
Characteristics Screening agent
Salt tolerance NaCl
Drought tolerance PEG
Mannitol
Sorbitol
Hydroxy-proline
Herbicide tolerance Related herbicide
Diseases resistance Pathogen culture filtrate
Phytotoxin Pathogen itself
10
Types of selection methods
  • Stepwise long term treatment
  • Cultures are exposed to stress with gradual
    increase in concentration of selecting agent
  • Shock treatment
  • Cultures are directly subjected to a shock of
    high concentration and only those which would
    tolerate that level will survive

11
The Advantage
  1. Freedom from the effect of climate and natural
    environment, which make it easier to measure
    slight difference in polygenic inherited traits
    horizontal or general disease resistance
  2. The ability to handle large numbers of
    individuals in a very small space
  3. The ability to work with the simpler genome of
    which allows the uncovering of recessive traits
    and additive characters within a relatively small
    population
  4. The ability to shorten the time of selection
  5. It can compliment field selection

12
The disadvantage
  1. Loss of regeneration ability during selection
  2. Lack of correlation between the mechanism of
    tolerance operating in the culture and those of
    the whole plants
  3. Phenomenon of epigenetics

It would emphasize here the necessity of growing
all in vitro selected plants in the field Very
often a powerful in vitro tolerance does not show
up at the whole plant level under field condition
Write a Comment
User Comments (0)
About PowerShow.com