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  • 8/17/2019 Surabhi Project-1.docx



    I would like to thank all the people who helped and supported me with writing this

    dissertation project.

    Firstly, I would like to express my deepest gratitude to my Supervisor, Dr. R.N. Singh

    for his unwavering support, collegiality and mentorship throughout this project. Without

    his guidance and persistent help this dissertation would have not been possible.

    I would also like to thank our college librarian who provided me the reuired books

    which helped me a lot to prepare my dissertation project.


  • 8/17/2019 Surabhi Project-1.docx



    1.  Introduction 2.  Aneuploids or Heteroploids;





    $. Euploidy

    %aploidy&!onoploidy 'iploidy


    $. Types of polyploids )

    a. *utopolyploids

     b. *llopolypliods

    5. Appliction of !olyploids.

    ". Role of polyploidy in plnts

    #. $onclusion

    % References.


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    *n individual carrying chromosome numbers other than true monoploid or diploid

    numbers is called heteroploids +Sharp, -$/. %eteroploidy is divided into euploidy and


    In polyploids, x is the basic +monoploid/ chromosome number, n is the gametic

    chromosome number of chromosomes, and 0n is the 1ygotic or somatic chromosome

    number for 2x) the genomic formula of #riticum aestivum is 0n30x3. In both cases,

    the basic chromosome number x3is seven.

    #he basic set of chromosomes in a diploid is called a genome.

    2very cell in the body of living organism is provided with a packet of genetic material

    +the nuscles/ which contains chromosomes. #he number of chromosomes in the nulei of 

    a given species is fixed.

    #he following chart gives the idea about the chromosome number in different organisms.

    species of plants and animals have identical chromosome numbers. In such cases one

    should not think that these organism will show similar characters, because it is not the

    number of chromosomes which differentiates various species from one another, but

    rather them nature of hereditary material in the chromosomes determine the character of 

    species. In most of plant and animals the chromosome number ranges between 4 and

    5o.#he number above and below this range are comparatively rare. #he highest number 

    of chromosomes reported so far is about 44 found in 6adiaolaria , an unicellular 

    marine proto7oa. In plants, chromosome number ranges from two pairs +in a member of 

    compositeae, %aplopappus gracilis/ to several hundreds found in ferns. In ophioglossum


  • 8/17/2019 Surabhi Project-1.docx


    89: chromosomes have been counted in each nucleus. In  chromosomes of pea there

    are 8 chromosomes of different shapes, si7es and structures and each kind of 

    chromosome has its own homologue. So there are 8 pairs of chromosomes in pea. #his

     basic number is denoted by the letter ;x< or ;n

  • 8/17/2019 Surabhi Project-1.docx


    ii/ #he growth rate decrease due to slower rate of cell division. #his leads to a

    decrease in auxin supply and decrease in respiration.

    iii/ #he time of blooming is delayed and prolonged due to slow growth rate.

    iv/ *t higher ploidy level) autoocotaploids or higher the adverse effects are highly

     pronounced and lead to the death of the plants.

    Induction of !olyploidy-)

    In recent years, a number of methods have been worked out to induce polyploidy in  plants. Some of them are described below.

    1. *y Rdition-)


  • 8/17/2019 Surabhi Project-1.docx


    (olyploidy can be induced in plants by exposing their certain parts, such as vegetative

     buds and flower buds, to ultraviolet rays, @)rays or other rays of shorter wavelengths.

    Irradiation increases the rate of cell division and also cause the multiplication of 

    chromosome number.

    2. *y Inury-)

    When the merismatic 7ones of a plant are injured the cells at the points of injury grow

    rapidly and form a callus. Aallus growth is enhanced by a chemical substance named

    coumerine which also brings about somatic doubling of chromosomes. Begetative buds

    generally developing from callus tissus are ployploid in nature, from injured part of 

    tomato plants it is possible to produce tetra ploids plants.

    /. *y $he+icl Tret+ent-)

    * number of chemicals are now known which induce polyploidy in plants. Important

    among them are colchicine, granosan. Ahloroform, chloral hydrate, some narcotics and

    alkaloids, *cenaphthene. Indolacetic acid, 2thyl)mercury chloride etc. colchicine is the

     best chemical for this purpose. It is a chemical compound which was first discovered by

    (ernice in ::-.

    Aolchicine was first demonstrated by levan to be a specific and efficient chemical in

    creating polyploidy restitution nuclei. Aolchicine is obtained from the extract of roots

    and corms of the colchicine outumnale. In india. It is obtained from colchicium luteum

    and glorios a superba.

    0ethods tested for colchicine tret+ent

    . #wigs could be immersed in solutions of various concentration for difference periods

    0. Seeds were immersed in colchicine solution for different periods


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    $. Seeds were germinated on blotting paper soaked in different concentrations of 

    colchicine solution.

    . Coung flower buds could be immersed in test tubes filled with different

    concentrations of colchicine for different periods.

    5. Begetative buds could be immersed in D.5 per cent and D.05 per cent aueous

    solutions of colchicine for different periods

    9. Aolchicine could be applied as a paste in anhydrous lanolin with D.)D.5 per cent


    8. Aolchicine solution could be sprayed on the growing buds.

    :. Erowing buds could be wetted with aueous solution.

    -. Solution of colchicine in agar may be applied to growing buds on interval.

    Adpt,ility of plnts to colchicine tret+ent

    #he different crop plants show different range of adaptability to the induction of 

     polyploidy by colchicine treatment. "ot the least, even different genotypes within a

    species too show different response to double the chromosomes. *ccording to loue

    +-5$/ and evan +-:/.

    . (lants low in chromosome numbers are more likely to respond well in doubling the chromosome than those higher in chromosome number.

    0. Aross)fertili7ing plants are more likely to successful for doubling the chromosome

    numbers than self)fertili7ering species.

    $. Begetatively propagated plants may be more successful as autopolyploid than seed

    grown plants.

    . Fertility of autotetraploids may be reduced to a great extent.


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    Effects of tret+ent

    #he changes brought by chromosome doubling are of great significance. >oth

    individually as well as doubling of chromosomes bring morphological, physiological

    and genetic changes.

     Morphological : eaves become large, darker in colour, leathery in texture ? leaf lobes

    get overlapped and twisted. Stomata, bracts, (ollen grains, bolls and seeds become

     bigger than control. !aturity is delayed.

    Immediate effect of seed treatment causes swelling of radicles and retardations of their 

    growth. Seedling show slow growth with thicker stem, darker and broader leaves.

    Si7e of pollen grain and guard cells are bigger than control plants.

    #he stems of polyploids are stouter and thicker, leaves are larger and broader, hair on the

    vegetative parts are coarse and thicker. #he floral, fruits and seeds are larger than


     "ormally, polyploids form gigas character because individual cell si7e becomes larger.

    Eigas character occurs in both naturally as well as artificially)induced polyploids.

     Physiological : >ecker in -$ reported that osmotic concentration in autopolyploids is

     proportional top the chromosome number.

    *utotetraploid mai7e takes longer time to mature than diploid. In fruits and vegetables,

    vitamin content is increased. In tobacco, nicotine content is increased and also nitrogen, calcium potas and magnesium but carbohydrate, sulphur and phosphorus decreases. In

    triploid beet, sugar content is increased.


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    #he decrease in growth rate slowly leads to the formation of perennial from annual types

    in cotton. Sharp -$ reported that autotetraploid 1ea race is perennial, while diploid is


    !olyploidy in !lnts-)

    Ahromosome doubling in Somatic and Eerm cells. #wo basic irregular processes

    have been discovered by which polyploids may evolve from diploid plants and become

    established in nature.

    . With somatic doubling cells sometimes undergo irregularities at mitosis and give rise

    to meriste