Plant-Microbe interaction
• Plants are non-motile but they constantly encounter both the biotic
and abiotic stress. There is a constant war between the pathogenic
microbes and the host plant – the outcome of which determines
resistance or disease.
• Plants secrete various organic compounds resulting in a nutritionally
enriched environment favorable for microbial growth.
• As a result, plants are heavily colonized with a diversity of microbes
whose reservoir is primary the soil.
• Microbes that colonize plants are called either epiphytes (colonize
plant surface) or endophytes (colonize plants interior)
• Microbial communities influence plants in direct and indirect ways.
• Plants and microbes can have variety of interactions including
pathogenic, symbiotic and associative.
Pathogenic Relationship
• The contact between plant and pathogenic microorganism lead to a
particular chain of events in plant organism.
• The extracellular space between cell wall and plasma membrane acts
as a first battle field between plants and pathogens.
• Bacteria, fungi, viruses and oomycetes that colonize the living plant
tissues are encased in this narrow region in the initial step of infection.
• Therefore, the apoplastic region is believed to be an interface which
mediates the first crosstalk between host and pathogen.
• The secreted proteins and other metabolites, derived from both host
and pathogen, interact in this apoplastic region and govern the final
relationship between them.
• Types of pathogen based on effects :
1. Necrotrophy : plant cells are killed
2. Biotrophy : plant cells remain alive
3. Hemibiotrophy : plant cells initially
alive later killed.
Symbiotic relationships
• Symbiosis refers to relationships between
organisms of different species that show an intimate
association with each other.
• Symbiotic relationships provide at least one of the
participating species with a nutritional advantage.
• 3 types of symbiosis have been recognized
depending on the nature of relationship.
Mutualism
Commensalism
Parasitism
