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PLANT PHYSIOLOGY

Faculty of Biology

Hanoi University of Sciences – VNU

2013 Dr. Lê Quỳnh MaiE-mail: [email protected]

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What is Plant?

is non-mobile

is autotrophic

has eukaryotic cells

has cell walls comprised of cellulose is multicellular

exhibits alternation of generations - has a

distinctive diploid (sporophyte) and haploid

(gametophyte) phase.

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What is Plant Physiology?

Plant physiology is a study of the plant way of life,which includes various aspects of the plant lifestyle

and survival including:

metabolism, water relations, mineral nutrition,photosynthesis, respiration,

growth, development, regulation, movement,

irritability (response to the environment)

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Arabidopsisthaliana ---

The

Helpful Study Materials

drosophila ofPlant

Kingdom

Why?

It has many advantages such as ….

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William G.

Hopkins

Plant Growth and DevelopmentMain Contents

1. The regulation of

development

Main

References

2. Major stagesduring the life cycle

3. Defense against

biotic enemies

4. Responding to

environmental

factors

p.453-492

p.369-424

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Three Terms

Growth Growth Growth Growth Changes (increase) in

size and mass=

+

Differentiation Differentiation Differentiation Differentiation

Development Development Development Development All of the changes in life cycle

characteristics and functions=

=

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Plant Cell Development

Cell division

Growth

Cell enlargement

Cell

differentiation

Differentiation

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Cell division

What? For what? Where? When?

Increase numberof cells

Createnew cells

Take place inMeristem

Always

can n uce ce v s on

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Cell enlargement

What?

Increase the size,

Cells

“grow up”

For what?

Where?

When?

vo ume w e

changes in shape and

content of cell

In enlongationzone

Always

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Cell wall extensibility

XET: Xyloglucan EndoTransglycosylase

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Cell differentiation

- Changes in

structure

- Changesfor different

functions

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To become A or B? … Why?

Totipotent

d i

A B

f f

e r e n t i a t i on

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E.g.

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Plant growth regulators

Messages

Cell A Cell B

Hormones

A hormone is a chemical released by a cell or a gland in one part of the body that

sends out messages that affect cells in other parts of the organism. In essence, it is

a chemical messenger that transports a signal from one cell to another.

All multicellular organisms produce hormones; plant hormones are called

phytohormones.

Adjustment activities

How do phytohormones differ from animal ones?

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Comparison

Animal hormones Plant hormones

Peptides/proteins/small organic

molecules

Small organic molecules

Synthesised in specialised Synthesised throughout the plant

glands

Affect distant targets (often

transported in the circulatory

system)

Affect local cells and tissues, or

can be transported through the

vascular system

Specialised effects Wide-ranging effects

Regulated by the central

nervous system

`Decentralised' regulation

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Main groups of phytohormonesHormone Function Location

Auxins

stem elongation

apical dominanace

root formation

produced in shoot

apical meristem

Cytokininscell division

differentiationproduced in roots

stem & intemode elongation produced in apical

seed germination portion of root & shootEthylene abscission

fruit ripening

produced in leaves, stems

& young fruits

Abscisic Acidsuppression of bud growth

stomatal closingleaf senescence

mature leaves, fruits &

root caps

Brassinosteroid

cell enlongation, cell expansion

promotion of vascular differentiation

growth promoting by stem enlongation

pollen tube formation, enlongation…

Wide range of plant

organs (short distance

activity)

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AuxinGibberellin

Ethylen

Auxin

Auxin

Transport of phytohormones

CytokininGibberellin

ABA

ABA

Ethylen

Auxin

Gibberellin

ABA

Cytokinin

Ethylen

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Phytohormone interaction

Genetical

regulationinteraction

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Plant hormones in stress responses

Signal

Rece tion

Transduction

Response

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Mechanism of transduction

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Light sensistive systems

Light

Phototropins

Cryptochromes

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Signal Perceiving Locations

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Recall……….

What should be studied in part of plant development?

Regulation of development Stages in life cycle

Rely on and Cope with conditions

How are the cells development?

Born from other divisions

Grow up step by step

Make their own characteristicsWhat are phytohormones?

Definition

Classification

Interaction

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Why are these molecules but not

others?

Selection process =

Selecting the most

suitable molecule

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growth promoting signal molecules

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stress signal molecules

Chemical stressOsmotic stress

Mechanical stressUV-oxidative stress

gd1 overview 2013

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