Climatic markers and provide adequate resolution 4)need

 

Climatic change, whether naturally
occurring or due to human activities, is one the greatest challenge in todays
world. Global crop production will be at considered at high risk as the areas
suitable for growing crops are rapidly decreasing due to rise in temperature
and frequent flooding events during recent decades, especially in the mid
latitude 1. The essential biological phenomenon in plants on the molecular
basis is significant for consideration , management  and efficiently utilization of plant genetic
resources (PGR). The sufficient knowledge about the present genetic
variation  in plants and how to use it is
one of the crucial enthusium for the conservation and suitable use of plant
genetic resource and to select high productivity and resistant variation ,it
requires accurate identification of their accession 2

       
The interesting advances in molecular genetic in the course of the most
recent couple of years have given novel techniques to the specialists involved
in the conservation of plant resources, with a scope of new systems for simple
and reliable identification of plant species.4

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The genetic marker concept is an old one; in the nineteenth century,
Gregor Mendal employed phenotype-based marker in his experiment on Drosophila melanogaster. The limitations
of these phenotypic-based markers led to the development of DNA based marker
called as molecular marker. The emergency of DNA based makers has changed the
practice of species identification technique.3

An ideal biomarker should possess the
following features

1)highly polymorphic in nature and evenly
distributed throughout the genome,

2)requires no prior knowledge about the
genome of an organism,

3)generate multiple, unique and reliable
markers and provide adequate resolution

4)need small amount of start-up material
and be simple, quick and inexpensive.

5) not possessing pleiotrophic or
epistatic and  link to distant phenotypes.

The one of the kind strategies of molecular
assessment differs from every other with respect to vital capability consisting
of genomic abundances, level of polymorphism detected, locus, specificity,
reproducibility, technical necessity and value rate. Relying   at the need, changes and modifications in the
technique have been made, leading to a second generation of advanced molecular
markers.

 
Genetic or DNA based marker techniques such as RFLP , RAPD, SSR , AFLP
are now in common use for ecological, evolutionary, taxanomical,  phylogenic and genetic studies of plant
science. These techniques are well established and their advantages and
limitations have been documented. ** 4. The recent advances and development of
high throughput sequencing technology proved the possibly of analysing high
number of samples over shorter period. The main objective of this review is to
provide the basic information and details about the recently developed
molecular marker technique and their application in genetic variability and
variations in plant science for the conservation of plant resources.

 

2.
Assessment of Genetic Variation by Molecular Markers

 Genetic variation analysis are typically based on
assessing the diversity of an individual by using both allozymes ( enzyme which
might be coded for by way of different alleles on the identical locus) or
molecular markers, which have a tendency to be selectively impartial. It has
been argued that the rate of loss of range of these neutral markers might be
better that those which might be associated with fitness. In order to verify
this  Reed and Frankham 5 performed a
meta-evaluation of health components in three or more populations and in which
heterozygosity, and/or heritability, and/or population  length have been measured. Their findings,
primarily based on 34 datasets, concluded that heterozygosity, populace size,
and quantitative genetic variation, which can be all used as indicators of fitness
have been all definitely correlated appreciably with populace fitness.

Genetic
variability within a population may be assessed via:

1.The wide variety
(and percentage) of polymorphic genes in the populace.

2.The number of
alleles for each polymorphic gene.

3.The share of
heterozygous loci per individual 6.

Proteic methods,
inclusive of allozyme electrophoresis, and molecular techniques, which include
DNA evaluation, giving a clear indication of the levels of genetic variant
found in a species or population 7 without direct interference from
environmental factors. However they have the disadvantage of being distinctly
luxurious, time eating and require excessive ranges of expertise and substances
in evaluation.

 

3)
Molecular Markers       

 

A molecular marker
is a DNA sequence (locus) in
the genome of an organism at which the DNA base sequence varies among the
different individuals of a population. These work by highlighting
polymorphism within a nucleic sequences between different individuals. These
polymorphism is due mutations and point mutations. Molecular markers may be
classified into following categories

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