Defence Mechanisms in Plants

Question 1

Plant defense mechanisms are decided mainly to?

Answer 1

Structural Defence Mechanism and Biochemical Defence Mechanism

Question 2

Structural defense mechanisms are mainly of two types:

Answer 2

Pre-existing structural defence
and Post-Infectional Structural defence

Question 3

Biochemical Defense Mechanism are mainly of two types:

Answer 3

Pre-existing Biochemical Defence and Post-Infectional Biochemical Defence

Question 4

EXAMPLES OF: Pre-existing structural defense mechanisms

Answer 4

Wax
Thick cuticle
Thickness and toughness of the outer wall of epidermal cells
Stomata
Sclerenchyma cells
Lenticels

Question 5

Pre-existing structural defense that mixture of a long chained apolar lipid, protective jelly which coats the plant leaves and fruits synthetization of the epidermis.
and It is extremely hydro-phobic.

Answer 5

Wax

Question 6

In linseeds, cuticle acts as a barrier against

Answer 6

Melampsora lini

Question 7

Silicification and lignifications of epidermal cells offers protection against

Answer 7

Pyricularia oryzae and Streptomyces scabies in paddy and potato, respectively

Question 8

cells are present in stem and leaf veins

Answer 8

Sclerenchyma Cells

Question 9

Sclerenchyma Cells effectively block the spread of some fungal and bacterial pathogens that cause

Answer 9

angular leaf spot

Question 10

Structures of Natural Openings are

Answer 10

Stomata and Lenticels

Question 11

name of a pathogen that cause stem rust of wheat can enters its host only when the stomata are open.

Answer 11

Puccinia graminis f.sp. tritici

Question 12

Small and suberized lenticels offer resistance to potato scab name the pathogen.

Answer 12

Streptomyces scabies

Question 13

Post-Infectional Structural Defense are mainly of two types:

Answer 13

Cellular defense structure and Histological defense structure

Question 14

Histological defense structure

Answer 14

Hyphal sheathing

Question 15

Histological defense structure is mainly of four types:

Answer 15

Formation of cork layer
Formation of abscission layer
Formation of tyloses
Deposition of gums

Question 16

defense structure that forms several layers of cells beyond the point of infection inhibits the further invasion by the pathogen beyond the initial lesion and also blocks the spread of toxic substances secreted by the pathogen.

Answer 16

Cork layers

Question 17

example of infected protected with Cork layers

Answer 17

Potato tubers infected by Rhizoctonia

Prunus domestica leaves attacked by Coccomyces pruniphorae

Question 18

defense structure consists of a gap formed between infected and healthy cells.

Answer 18

Abscission Layers

Question 19

defense structure that overgrowths of the protoplast of adjacent living parenchymatous cells, which protrude into xylem vessels through pits.

Answer 19

Tyloses

Question 20

defense structure secretion is most common in stone fruit trees but occurs in most plants.

Answer 20

Gum Deposition

Question 21

the process in which gum produced by the plants and trees.

Answer 21

Gummosis

Question 22

when can observed Hyphal sheathing in flax infected with?

Answer 22

Fusarium oxysporum f.sp. lini

Question 23

Biochemical Defence Mechanism are mainly of two types:

Answer 23

Pre-existing chemical defence and Induced chemical defence

Question 24

what are Pre-existing chemical defence

Answer 24

Inhibitors () and Phenolics

Question 25

example of Inhibitors released by a Plant in it is Environment

Answer 25

Ex 1: Root exudates of marigold contain α-terthinyl which is inhibitory to nematodes. Ex 2: In Cicer arietinum (chickpea), the Ascochyta blight resistant varieties have more glandular hairs which have maleic acid which inhibit spore germination. Ex 3: Red scales of red onion contain the phenolic compounds; protocatechuic acid and catechol.

Question 26

inhibitory compound present in the cell before infection

Answer 26

Phenolics: onion (catechol and protocatechuic acid ). Tannins : -Dienes: fatty acid-like compound - Chlorogenic acid: in potato inhibits common scab bacteria Saponins -Tomatine in tomato and Avenacin in oats

Question 27

Chemical defenses

Answer 27

ricin: from Castor oil beans Just 0.2mg would be fatal if Citronella: from lemon grass Insect repellents pyrethrins: made by chrysanthemums and act as insect neurotoxins. caffeine: toxic to insects and fungi

Question 28

Antibacterial compounds –cotton

Answer 28

antibacterial glossypol

Question 29

organelles containing enzymes that break down bacterial cell walls.

Answer 29

Lysosomes

Question 30

enzymes that break down the chitin in fungal cell walls

Answer 30

Chitinases

Question 31

Gluconates (Anti-oomycetes)

Answer 31

enzymes made by some plants that break down glucans; polymers found in the cell walls of oomycetes (e.g. P. infestans)

Question 32

species of Sambucus (elderberry) toxins produce

Answer 32

produce chemicals that can be metabolized (broken down) to form cyanide compounds. cyanide-inducing glycoside