role of growth
Post on 06-Apr-2018
221 Views
Preview:
TRANSCRIPT
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 1/45
ROLE OF GROWTH
REGULATERS ON IN-VITRO
MORPHOGENESIS OF PLANT
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 2/45
GUIDED BY
DR.Swarnalata Mishra
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 3/45
CONTENTS
INTRODUCTION
WHAT IS IN-VITRO MORPHOGENESIS
WHAT IS GROWTH REGULATERS
TYPES OF GROWTH REGULATERS
AUXIN
CYTOKININS
GIBBERELLINS
ABSCISIC ACID
ETHYLENE
ROLE OF GROWTH REGULATERS
IN CASE OF INVITRO MORPHOGENESIS
CONCLUSION
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 4/45
INTRODUCTION
WHAT IS IN-VITRO MORPHOGENESIS
IN VITRO(Latin-With in the glass)
MORPHOGENESIS:-Formation of the structure of an organism or part;
differentiation & growth of tissues & organs during development.
IN VITRO MORPHOGENESIS:-Formation of the structure of an
organism or part ; differentiation & growth of tissues & organs during
development in an artificial environment i.e out side the living organism
that means within the glass.Modern tissue culture in case of plants & animals is a bright example of
invitro morphogenesis.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 5/45
WHAT IS GROWTH REGULATERS
Internal and external signals that regulate growth are mediated, at least in
part , are known as Growth Regulaters.They are otherwise known as
growth hormones.
These are of two types:- Plant growth regulaters/Phytohormones
Animal growth regulaters /
Plant hormones differ from animal hormones in that:
No evidence that the fundamental actions of plant and animalhormones are the same.
Unlike animal hormones, plant hormones are not made in tissues
specialized for hormone production. (e.g., sex hormones made inthe gonads, human growth hormone - pituitary gland)
Unlike animal hormones, plant hormones do not have definite target areas (e.g.auxins can stimulate adventitious root development in a cut shoot, or shoot elongation or apical dominance, or differentiation of
vascular tissue etc).
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 6/45
PLANT GROWTH REGULATORSPLANT GROWTH REGULATORS
PLANT GROWTH REGULATORS ARE NECESSARY FOR,BUT DO NOT CONTROL, MANY ASPECTS OFPLANT GROWTH AND DEVELOPMENT. ² BETTER NAME IS GROWTH REGULATOR.
THE EFFECT ON PLANT PHYSIOLOGY IS DEPENDENON THE AMOUNT OF HORMONE PRESENT ANDTISSUE SENSITIVITY TO THE PLANT GROWTHREGULATOR.
Substances produced in small quantities by a plant, and thentransported elsewhere for use .
Have capacity to stimulate and/or inhibit physiological processes.
At least five major plant hormones or plant growth regulators:
ooauxins, cytokinins, gibberellins, ethylene and abscisic acidauxins, cytokinins, gibberellins, ethylene and abscisic acid
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 7/45
TYPES OF PLANT GROWTHTYPES OF PLANT GROWTH
REGULATERSREGULATERS
Auxins Auxins (cell elongation)
GibberellinsGibberellins(cell elongation + cell division - translated into
growth)
CytokininsCytokinins (cell division + inhibits senescence)
Abscisic acid Abscisic acid (abscission of leaves and fruits + dormancy induction of buds and seed)
EthyleneEthylene (promotes senescence, epinasty, and fruit ripening)
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 8/45
AUXIN
Auxin increases the plasticity of plant cell walls and is involved in
stem elongation.
Arpad Paal(1919):- Asymmetrical placement of cut tips on
coleoptiles resulted in a bending of the coleoptile away from the
side onto which the tips were placed (response mimicked the
response seen in phototropism).
Frits Went (1926) determined auxin enhanced cell elongation.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 9/45
Demonstration of transported chemicalDemonstration of transported chemical
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 10/45
Auxin Auxin
Discovered as substance associated with phototropicresponse.
Occurs in very low concentrations.
Isolated from human urine, (40mg 33 gals
-1
)
In coleoptiles (1g 20,000 tons-1)
Differential response depending on dose.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 12/45
Auxin Auxin
Auxin promotes activity of the vascular cambium and vascular
tissues.
o plays key role in fruit development.
Cell Elongation: Acid growth hypothesisCell Elongation: Acid growth hypothesis
auxin works by causing responsive cells to actively transport
hydrogen ions from the cytoplasm into the cell wall space.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 13/45
SignalSignal--transduction pathways in plantstransduction pathways in plants
Auxin interacts with calcium ions which in turn
calmodulin, a protein, which regulates many processes
in plants, animals, and microbes.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 14/45
Loosening of cell wallLoosening of cell wall
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 15/45
Polar transport of AuxinPolar transport of Auxin
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 16/45
Auxin
Synthetic auxins :- widely used in agriculture and horticulture
prevent leaf abscission
prevent fruit drop promote flowering and fruiting
control weeds
Agent Orange: - 1:1 ratio of 2,4-D and 2,4,5-T used to
defoliate trees in Vietnam War.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 17/45
Additional responses to auxin Additional responses to auxin
Abscission :- loss of leaves
Flower initiation
Sex determination
Fruit development Apical dominance
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 18/45
Control of abscission by auxinControl of abscission by auxin
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 19/45
Apical Dominance
Lateral branchgrowth are inhibitednear the shoot apex,
but less so fartherfrom the tip.
Apical dominance
is disrupted in someplants by removing the shoot tip, causing the plant to become
bushy.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 21/45
Gibberellins
Gibberellins are named after the fungus Gibberella
fujikuroi which causes rice plants to grow abnormally
tall.
synthesized in apical portions of stems and roots
important effects on stem elongation
in some cases, hastens seed germination
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 22/45
Effects of GibberellinsEffects of Gibberellins
Cell elongation.
GA induces cellular division and cellular elongation; auxininduces cellular elongation alone.
GA-stimulated elongation does not involve the cell wallacidification characteristic of auxin- induced elongation
Breaking of dormancy in buds and seeds.
Seed Germination - Especially in cereal grasses, like
barley. Not necessarily as critical in dicot seeds.Promotion of flowering.
Transport is non-polar, bidirectional
producing general responses.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 23/45
Gibberellins and Fruit Size
Fruit Formation - "Thompson Seedless" grapes grown
in California are treated with GA to increase size anddecrease packing
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 24/45
Mobilization of reservesMobilization of reserves
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 26/45
Discovery of cytokininsDiscovery of cytokinins
Gottlieb Haberlandt in 1913 reported an unknowncompound that stimulated cellular division.
In the 1940s, Johannes van Overbeek, noted that plant embryos grew faster when they were supplied withcoconut milk (liquid endosperm) , which is rich in nucleicacids.
In the 1950s, Folke Skoog and Carlos Miller studying theinfluence of auxin on the growth of tobacco in tissueculture. When auxin was added to artificial medium, thcells enlarged but did not divide.
Miller took herrin -s erm DNA. Miller knew of
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 27/45
Discovery of cytokininsDiscovery of cytokinins
Adenine or adenine-like compounds induce cell divisionin plant tissue culture. Miller, Skoog and their coworkersisolated the growth factor responsible for cellular divisionfrom a DNA preparation calling it kinetin which belongsto a class of compounds called cytokinins.
In 1964, the first naturally occurring cytokinin wasisolated from corn called zeatin. Zeatin and zeatinriboside are found in coconut milk. All cytokinins(artificial or natural) are chemically similar to adenine.
Cytokinins move nonpolarly in xylem, phloem, andparenchyma cells.
Cytokinins are found in angiosperms, gymnosperms,
mosses, and ferns. In angiosperms, cytokinins areroduced in the roots seeds fruits.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 28/45
CytokininsCytokinins
Cytokinins, in combination with auxin, stimulate cell
division and differentiation. most cytokinin produced in root apical meristems
and transported throughout plant
inhibit formation of lateral roots
auxins promote their formation
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 29/45
Function of cytokininsFunction of cytokinins
Promotes cell division.
Morphogenesis.
Lateral bud development.
Delay of senescence.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 31/45
Abscisic acid Abscisic acid
In 1940s, scientists started searching for hormones that would
inhibit growth and development,what Hemberg called dormins.
n the early 1960s.Philip Wareing confirmed that application of
a dormin to a bud would induce dormancy ..T. Addicott discovered that this substance stimulated abscission
f cotton fruit . He named this substance abscisin(Subsequent
esearch showed that ethylene and not abscisin controls abscissiobscisin is made from carotenoids and moves nonpolarly
hrough plant tissue.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 33/45
Abscisic Acid
Abscisic acid is produced chiefly in mature green leave
in fruits.
Suppresses bud growth and promotes leaf senescence. Also plays important role in controlling stomatal openin
closing.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 34/45
Functions of abscisic acidFunctions of abscisic acid
General growth inhibitor.
Causes stomatal closure.
Produced in response to stress.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 35/45
Discovery of ethyleneDiscovery of ethylene
In the 1800s,it was recognized that street lights that burned
gas, could cause neighboring plants to develop short,thick
stems and cause the leaves to fall off. In 1901, Dimitry
Neljubow identified that a byproduct of gas combustionwas
ethylene gas and that this gas could affect plant growth.
In R.Gane showed that this same gas was naturally produc
by plants and that it caused faster ripening of many fruits.
Synthesis of ethylene is inhibited by carbon dioxide and
requires oxygen.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 36/45
EthyleneEthylene
H H
\ /
C = C
/ \
H H
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 37/45
Functions of ethyleneFunctions of ethylene
aseous in form and rapidly diffusing.
Gas produced by one plant will affect nearby plants.
Fruit ripening.
Epinasty ² downward curvature of leaves.
Encourages senescence and abscission.
Initiation of stem elongation and bud development.
Flowering - Ethylene inhibits flowering in most species, but
promotes it in a few plants such as pineapple,bromeliads andmango.
Sex Expression - Cucumber buds treated with ethylene
become carpellate (female) flowers, whereas those treated
with gibberellins become staminate (male) flowers.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 38/45
LE OF GROWTH REGULATER
IN CASE OF IN VITRO MORPHOGENESIS PLANTS:-
The in vitro growth of the plant cells occurs in a suitable medium
containing all the requisite elements.
The ingradients of medium effect the growth & metabolism of cell.Effect of growth regulaters on different parts of same plant or on
different species in relation to metabolite formation are variable.
There are some examples , where growth regulaters like;
Auxin,Cytokinin,gibberellins,ABA,Ethylene etc. shows various role in
growth induction/inhibition on different parts of same plant or
on different species .
Cytokinin & Auxin affect organogenesis.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 39/45
IN EX-PLANT CULTURE
An excised pieces of differentiated tissue or organ isregarded as an ex-plant. The ex-plant may be taken from
any part of the body. e.g.root,steam,leaves.
Shoot formation in in vitro morphogenesis is a part of
ex-plant culture. Shoot formation in plant is induced by the
combine action of cytokinin & auxin (low/no auxin+ high
cytokinin).
Root formation in vitro morphogenesis is induced by (hig auxin + low/no cytokinin) concentration.
Leaf culture in vitro morphogenesis is induced by (high aux
+ low/no cytokinin) concentration.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 40/45
IN EX-PLANT CULTURE
Callus culture:-Callus is the undifferentiated and unorganised
mass of plant cells.
Callus culture in vitro morphogenesis is induced by (high
auxin + low/no cytokinin).Seed germination is induced by the effect of growth regulater
gibberellin .
Somaclonal variation:-The genetic heterogeneity of cells in a
population represents continuity of genotypes,whereasphenotypically the population is represented as a dicrete sum
of subclones.Somaclonal variation is induced when the
concentration of auxin & cytokinin is same.
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 41/45
(undifferentiated plant cells) tissue(undifferentiated plant cells) tissue
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 42/45
Callus culture in Sorghum
8/3/2019 Role of Growth
http://slidepdf.com/reader/full/role-of-growth 43/45
LUS & SHOOT INITIATION IN TOM
top related