Role of Cytogenetics In Plant Improvement-Theory of Evolution and Darwinism-Assignment Solution, Exercises for Evolution. Aligarh Muslim University

Evolution

Description: This is solved assignment for Evolution course. It was submitted to Prof. Gorakh Varma at Aligarh Muslim University. It includes: Role, Cytogenetics, Plant, Improvement, Development, Organisms, Structural, Variations, DNA, Assisted, Breeding, Fiber
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What is the role of cytogenetics in plant improvement?

Cytogenetics is the science of chromosome number, shape, type and their inheritance,

recombination and expression. It is the science which deals with the evolution and

improvement of organisms.

During last few decades, plant cytogenetics has got a drastic improvement with the help

of molecular techniques. Development in plant cytogenetics can be divided into some

phases.

1. In first phase of development the scientists focused on the structural and

numerical variation of the chromosomes.

2. In the second phase of development in cytogenetics, scientists concentrated on

the DNA content and composition of unique as well as repeated forms of DNA

fragments.

3. The third phase of cytogenetics brought the trend of marker assisted breeding,

marker associated traits and use of molecular markers in detecting linkages.

This technique led to the formation of physical maps of chromosomes of various

plants.

4. Later era led to the study of whole genomics of plants and gene sequencing,

chromatin remodeling and histone coding.

Cytogenetics has played a very important role in producing new and improved varieties

of plants in order to fulfill the food, fiber and shelter requirements of human beings. One

of the great examples is GM crops.

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Genetically modified plants:

Genetically modified (GM) plants have altered DNA, using genetic engineering techniques. It is done to introduce a new character to the plants

which they do not have already. GM plants are still not very popular among the

people as there might be many health risks related to them. Review of some of

the GM plants is given below:

1. The most widely accepted and highly used GM crop is GM Soybean which contains resistant gene to herbicides glycophosate.

This resistant gene has been extracted from bacteria resistant to

herbicides. 77% percent people all over the world use this GM

soybean. 2. Bt. Cotton is the 2nd highest exploited crop, all over the world. It

has been grown by 49% of cotton growers in the world. Bt. Cotton

imposes resistance to pests by producing Cry toxin. This Cry toxin

producing gene has been obtained from a soil bacterium Bacillus

thuringiensis. 3. Bt. Maize is also an important and extensively accepted GM crop.

Bt. Maize has also the same CRY1-gene as in the Bt. Cotton. It

has also been made resistant to herbicides glycophosate by

inserting a resistance gene from bacteria. Some genes from South

African white corn have also been inserted in the GM maize in

order to obtain bright orange kernel with high degree of vitamin C

and carotene. 4. Experiments on falvr savr tomato production are on a high swing

now a day. Technology used to produce flavr savr tomato is the

insertion of antisense gene, responsible for production of an

enzyme polygalacturonase (PG). This antisense gene restricts the

production of PG enzyme which initiates ripening/softening in the

fruit after harvest. Flavr savr tomatoes have been taken off from

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the markets of USA because it did not get commercial acceptance

but, they are still being grown in China on small scale. 5. Prototype GM rice contained three transgenes. Two of which came

from daffodil and one from a soil bacterium. Latest golden rice

contains genes from maize and a soil bacterium. Golden rice

shows enhanced content of bêta carotene, which is a source of

vitamin A. It is assumed that the golden rice would be marketed in

the year 2013.

No doubt the knowledge of cytogenetics has played a vital role in crop improvement and

we expect much more prospects from this field.

References:

 Nathan M. Springer. Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, MN 55108, USA

 Scott A. Jackson  

Department of Agronomy, Purdue University, West Lafayette, IN 47906, USA

© The Author 2010. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org

 http://en.wikipedia.org/wiki/Genetically_modified_plant 

http://en.wikipedia.org/wiki/Genetically_modified_food 

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