Ethylene-Gas hormone

1. ETHYLENE-
Gas hormone!!!
Dr.R.Salini
Department of Biochemistry
V.V.Vanniaperumal College for
Women
Virudhunagar

2. History
Neljubow-1901
Ethylene remarkably alter the tropistic responses of roots
Denny-1924
induces fruit ripening
Gane-1934
natural product of ripening fruits
Ethylene
 gas-at temperature which plant can live
 found in plants and act as a hormone
 produced by leaves, flowers, stems, roots, tubers and seeds
 maximum production-maximum respiration
 senescence in fleshy fruits- increase in respiration
 endogenous ethylene- correlative growth inhibitor
 exogenous supply of ethylene- responses similar to concentration of auxin

3. Ethylene biosynthesis
meristematic regions and nodal regions
during leaf abscission and flower senescence, as well
as during fruit ripening
physiological stresses: wounding, flooding, chilling,
disease, temperature or drought, etc.
Sources:
gymnosperms and lower plants, bacteria, fungi
even marine sponge and cultured mammalian cells
can respond to ethylene.
the biologically active concentration: 1L L-1.

4. ACC-Aminocyclopropane carboxylic acid
Methythioadenosine

5. Mechanism of ethylene action
Membrane permeability
increases the permeability of cell membrane
Nucleic acid and protein metabolism
derepress genes- synthesis of specific mRNA and enzymes
Cellulase, chlorophyllase, protease, amylase, catalase, peroxidase
Regulation of auxin metabolism
reduces biosynthesis of auxins
inhibit transport from the region of synthesis to site of action

6. Role and application
Abscission
 accelerator of abscission
 inducing cell wall destroying enzymes – induces abscission
 called as phytogerontological hormone

7. Natural ripening and climacteric rise
 act as natural ripening hormone
 modify the permiability of cell membrane – enhance the activity of enzymes
attached to the cell wall
 permeability increases due to- degradation of phospholipid- phospholipase

8. Activation of malic enzyme
and
pyruvate decarboxylase
Respiratory Quotient
during climacteric rise- RQ = O2 consumed
increased CO2- increased RQ
this due to the action of malic enzyme and pyruvate decarboxylase

9. Degreening of citrus and banana fruits
 Degreening using ethylene- tricle method
 Chlorophyllase

10. Ripening

11. Thank you