Ethylene c 2 h 4
This presentation is the property of its rightful owner.
Sponsored Links
1 / 52

ETHYLENE C 2 H 4 PowerPoint PPT Presentation


  • 130 Views
  • Uploaded on
  • Presentation posted in: General

ETHYLENE C 2 H 4. Plant Hormone. Regulatory functions in growth and development Stimulators or inhibitors. Physiological Effects of Ethylene. Normal growth and development Stress response biotic and abiotic. Ethylene in organisms. Animal Production: not normal Effect:

Download Presentation

ETHYLENE C 2 H 4

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


ETHYLENEC2H4


Plant Hormone

Regulatory functions in

growth and development

Stimulators or inhibitors


Physiological Effects of Ethylene

Normal growth and development

Stress response

biotic and abiotic


Ethylene in organisms

Animal

Production: not normal

Effect:

82+ % as anesthetic in 15 second

ignition at humidity lower than 56 %


Ethylene in organisms

Bacteria

Bacterial rot of cauliflower

Fungi

Pennicilium digitatum

Aspergillus flavus

Alternaria solani


Ethylene in organisms

Neljubov(1901):

Gaseous hydrocarbon olefin

Triple response in etiolated pea seedlings

Cousins (1910):

Orange and banana in the same shipment


Gane(1934):

Ethylene as a natural plant product


Ethylene Diffusibility

Easily released from tissues

Diffuse through the gas phase

intercellular and outside

Rapid and sensitive response system

Active concentration:10 ppb


Ethylene

Biosynthetic

Pathway

(1979)


Alternative pathway

Peroxidation of

long chain fatty acids

eg. Linolenic acid


Met SAM ACC Ethylene

N-Malonyl ACC

(Nonvolatile compound)


Synthesized in most tissues of

almost all higher plants

Easily isolated and quantified

Also found in gymnosperms

lower plants

bacteria


Ethylene Production

Environmental effect

* O2 O2 C2H4 (except rice)

* Temperature

apple T P

peanut / plum T P

* CO2

appleP

sweet potatoP

beanno effect


Ethylene Production

Other hormones

Auxin: activate production: 10x

GA:activate in bean citrus blueberry

inhibit in soybean seedling

CK: activate in bean blueberry sorghum

ABA: activate in leaf and fruit

inhibit in seed and soybean seedling


Enzymes in Ethylene Biosynthetic Pathway


ACC Synthase or ACCS

Rate-limiting step of pathway

SAM to ACC

ACCS level

Hormone levels

Growth environment

Physiological environment

Developmental environment


ACC Synthase or ACCS

Amino acid sequences of

tomato, apple, squash and zucchini

Share 40% identity and 80% similarity

Contain 7 highly conserved regions


ACC Synthase or ACCS

Different isoforms

Encoded by a multigene family


ACC oxidase or ACCO

Require aerobic conditions

ACC to Ethylene

ACCO level:

environmental stresses


ACC oxidase or ACCO

Ethylene-forming enzyme : EFE

A ripening-induced cDNA

confers yeast an oxidase activity


ACC-N-Malonyl transferase

ACCM

Autoregulation to prevent

ethylene overproduction

Storage / inactive form of ACC


Ethylene transport

Diffusion (short distance)

ACC (long distance)


Ethylene metabolism

oxidation and hydrolysis

Ethylene oxide

ethylene glycol

Glucose conjugates of ethylene glycol

CO2


Ethylene Action

CS2 a potent inhibitor

of ethylene oxidation

No effect on ethylene responses

Action of ethylene ……..?


*Ethylene effects

not general for all plants

*A signal of environmental changes

or physiological changes


*Manifold effects mediated by

induction of new proteins

*regulator or

modulator or

coordinator of processes


Ethylene

Perception by receptors

Signal transduction

Responses


Ethylene binding

Ethylene receptors

Hypothesis

Reversibly binding to a receptor

through a transition metal


Ethylene-binding components

Membrane bound

Solubility

Chromatographic behaviors

Sensitive toheat

protease

sulfhydryl agent

Nature of protein


Ethylene-binding proteins (EBP):

Various tissues and plants

tobacco, bean, Arabidopsis

Specific

High affinity

Saturable

Characteristics of receptor

binding moiety facing the apoplast


Ethylene binding protein

EBP of Phaseolus vulgaris

Heterotrimer or

Heterotetramer

Subunits of ca. 12 to 14 kDa

Integral membrane protein


ETR

Receptor found in Arabidopsis

Dimer

Subunits of 79 to 83 kDa

3 transmembrane segments


Classes of ethylene-binding proteins

- High rate constant of

association/dissociation

- Very low rate constant of

association/dissociation


Classes of ethylene-binding proteins

2 classes

rice tomato

pea Arabidopsis

Class 2:

bean (Phaseolus)

mungbean


Ethylene-insensitive mutant

Arabidopsis

Decreased ethylene binding

Low concentrations of

ethylene binding protein


Antibody against Phaseolus EBP

Recognize homologous proteins

from pea

rice

Arabidopsis


Signal transduction pathway

Signaling pathway

A two-component system

bacteria

common / well-characterized

key mechanism

protein phosphorylation


2-component signaling pathway

Histidine kinase for

sensing / transducing

extracellular signals


2-component signaling pathway

Phosphotransfer between

two types of signal transducers

Sensory kinase

(input & kinase domains)

Response regulator

(receiver & output domains)


Ethylene signal transduction pathway

Genetic and biochemical studies

Similar to a bacterial two-component system

Conserved residues for kinase activity in EBP

Phosphorylation of EBP upon binding of ethylene


Ethylene

kinase

Response

regulator

P

P

ATP

Response

Model for regulation

of ethylene action


  • Ethylene binding

  • Autophosphorylation of kinase

  • Phosphate transfer to a response regulator

  • Release of an activated ligand or

  • activation of soluble factor

  • Derepression of genes involved in

  • ethylene responses


Model of ethylene signal transduction

RAN1

Cu

ETR1 ETR2 EIN4

ERS1 ERS2

Air

CTR1

EIN2

EIN3

OFF


Model of ethylene signal transduction

RAN1

Cu

ETR1 ETR2 EIN4

ERS1 ERS2

C2H4

CTR1

EIN2

ON

EIN3


Model of ethylene signal transduction


Regulation of ethylene

synthesis and activity

Activated by

high auxin

fruit ripening

flower senescence

wounding

chilling injury

drought

ACCS


Regulation of ethylene

synthesis and activity

Inhibited by

ABA

ethylene

AVG

AOA

ACCS


Regulation of ethylene

synthesis and activity

Activated by

ripening

senescence

ethylene

ACCO


Regulation of ethylene

synthesis and activity

Inhibited by

anaerobiosis

Co2+

high temp (35+)

ACCO


Regulation of ethylene

synthesis and activity

Ethylene level : Metabolism / Environment

Silver ion

CO2 (high conc at 3 to 5%)

NBD (2,5-norbornadiene)

DACP (diazo-cyclopentadiene)

Cyclic olefins

Cis butene

Ethylene binding


Commercial uses of ethylene

- Ethylene- Acetylene - ACC

- Ethylene-releasing compounds

Ethephon / Ethrel

*******************************************

- Ventilation with hypobaric pressure

- Silver- AVG / AOA- KMnO4


Ethylene / cell expansion / triple response

thicker and shorter Root/hypocotyl

reorientation of cell expansion


  • Login