HOW DO PLANTS DEFENSE THEMSELVES

HOW DO PLANTS DEFEND THEMSELVES

To prevent further spread of infection, healthy plant cells around the site of infection will die.

Ø Plant defense mechanism

ü Structural defense

Physical barriers that inhibit pathogens from entering into the host cell

ü Chemical defense

Produce substances that either toxic to the pathogen or inhibit growth of pathogen

Ø Preexisting structural defenses

                              I.            Amount and quality of wax and cuticle

                           II.            Structural of epidermal wall

                       III.            Size, location and shapes of stomata and lenticels

                       IV.            Thick walled cells – hinder the advance of the pathogen

Example of natural waxes on leaf and fruit

Leaf tissue anatomy

Induced structural defense :

a.    Cytoplasmic defense reaction	·       Some cytoplasm will surround the mass of hyphae
b.    Cell wall defense  structures	·       Morphological changes of cell wall structures such as swelling, cell wall thicken and callose papillae
c.     Histological defense structures	·       Formation of cork layer ·       Formation of abscission layer ·       Formation of tyloses ·       Deposition of gums
d.    Necrotic defense reaction	·       Hypersensitive response

Formation of cork layers

Formation of abscission layers

Formation of tyloses

Formation of gums

Ø Preexisting chemical defense

Inhibitor released by the plant in its environment is Fungitoxic exudates- inhibit germination of spores, while inhibitors present in plant cells before infection are Phenolic compound, saponins Hyrolytic enzymes,

Induced biochemical reaction :

a)    Hypersensitive response

Induced the death of host plant cell at the site of infection. Limit the growth of pathogen

b)   Active oxygen radiacals

Distrupt the cell membrane

c)    Strengthening molecules

Reinforcement of cell wall

d)   Antimicrobial substances

To kill the pathogen

e)    Immunization of plants against pathogen

Defense through plantibodies

f)     Local and systematic acquired resistance

Induction of plant defenses by artificial inoculation with microbes or treatment with chemicals which is Local acquired resistance and Systemic acquired resistance

REFERENCES :

www.defensesplant.com.my

www.formationcorklayer.com

prepared by : Tuan Muhamad Shaiful Nizam Bin Tuan Aziz (Agronomy Student), UiTM