Question

4. Formation of swelled tyloses in vascular tissue is an example of a constitutive (continuous) plant defense. (T or F) 5. The gene for gene concept explains how horizontal resistance works. (T or F)

Answer 1

4. Formation of swollen tyloses in vascular tissue is an example of a constitutive (continuous) plant defense: FALSE.

Plant defense mechanisms may be CONSTITUTIVE (CONTINUOUS) or INDUCED. Constituted type is always present in the plant while induced is produced in response to the destruction caused by predators (in this case herbivores).

Tyloses are formed by environmental stress on the plant like wounds or pathogens or when partly consumed by herbivores. As a part of defense mechanism, the parenchyma cells of parenchyma project into the lumen of adjoined vessels via vessel parenchymal pits.

Hence, this is not continuous or always present in the plant and only induced by stimuli. Thus it is Inducive type of plant defense, but not Constitutive or continuous

5. The gene for gene concept explains how horizontal resistance works: TRUE.

Horizontal resistance is a polygenic resistance where the individual genes work as gene for gene basis with the virulence genes in the pathogen. Hence, the gene for gene concept explains how the Horizontal resistance works