Enzymes In Pathogenesis PPT (Plant-Parasite Interactions – 1 Enzymes in Plant Pathology PPT)
What are enzymes involved in plant pathogenesis / pathology? Role of Enzymes in plant pathology? Different enzymes in plant paghogenesis- Cutinase, Pectinase, Cellulase, Hemicellulase, Ligninase, Lipase and Proteinase.
Primary Meristem vs Secondary Meristem (Similarities and Differences between Primary and Secondary Meristem)
Meristems are a group of plant cells that remain in a continuous state of division. The meristematic cells continuously produce new cells through the life of the plant. In previous posts, we have discussed the Characteristics of Meristematic Cells, Classification of Meristems and Difference between Meristematic and Permanent Tissues. Meristems are classified into different categories based on different criterions. In one such classification, the meristems are classified into two groups based on the nature of cells giving them. These two groups are (1) Primary Meristem and (2) Secondary Meristem.
(1). Primary Meristem: Primary meristems are the direct descendants of the embryonic cells. They continuously involved in the cell division and growth process of the plant. Example: apical meristem of shoot apex and root apex.
(2). Secondary Meristem: Secondary meristems are the meristematic tissue arises from the permanent tissues. Secondary meristems are usually lateral meristems and are responsible for the increase in thickness of the plant. Example: vascular cambium and cork cambium (phellogen).
The present post describes the Similarities and Differences between the Primary Meristem and Secondary Meristem.
Toxins in Plant Pathogenesis Toxins in Plant Pathogen Interaction
The process of pathogenesis (the onset of diseased condition) in plants is facilitated by many factors such as virulence of the pathogen, susceptibility of the host, presence of suitable environmental conditions and various enzymes and metabolites of pathogens. Previously we have discussed the importance of different enzymes involved in plant pathogen interactions. These enzymes facilitate the entry of the pathogen into the host and help to colonize inside the host cell. The production of different hydrolytic enzymes may not always result in the establishment of pathogen inside the host tissue. Certain plant pathogen may successfully invade the host tissue area but fail to induce the onset of disease. These findings highlighted the involvement of certain toxins, microbial toxins or aggressins, in the establishment of diseased conditions in plants. The present post describes the Toxins involved in plant pathogen interaction and pathogenesis with examples.
What is meant by ‘toxin’ in Plant Pathology?
ØDefinition: Any substances produced by a pathogen which is injurious to host and it directly and immediately play a crucial role in pathogenesis.
Ø Toxins involved in plant parasite interactions are also called as aggressin.
Ø According to Koch’s postulates, a substance to be called as a ‘toxin’ should follow the following criterions:
@. The compound must be isolated from the diseased plant
@. It should NOT be present in the healthy plant
@. Compound must be chemically characterized
@. When isolated toxin is reintroduced to a healthy host, it should produce the original symptoms.
(Plant-Pathogen Interaction Part I: Enzymes in Plant Pathology)
What are the enzymes involved in pathogenesis (plant pathology)?
Most of the fungal and bacterial parasites produce many enzymes that degrade the plant materials in vivo. Enzymes involved in pathogenesis or virulence (process of disease initiation) includes both constitutive and inducible enzymes.
(1). Constitutiveenzymes are those enzymes which are present all the time in the cells.
(2). Inducible enzymes are those enzymes which are produced only when they are needed by the cells in response to certain internal or external stimuli.
Important classes of enzymes involved in pathogenesis are: