Plants naturally interact with various microorganisms like bacteria, fungi and nematodes. They can become infected by viruses when insects feed on them and transmit pathogens. Plant pathogens have adapted strategies to invade plants, overcome their defenses, and colonize tissues to survive and reproduce. Pathogens secrete chemicals affecting host components and metabolism. Penetration and invasion are also aided by mechanical force exerted by pathogens on plant cell walls.

1. By
By
Hem
Hem Chander
Chander
Assistant Professor (Botany)
Assistant Professor (Botany)
Career Point University
Career Point University Hamirpur
Hamirpur (HP) 176041
(HP) 176041
hemchander78@gmail.com
hemchander78@gmail.com

2.  Plants have natural interactions with bacteria, fungi, nematodes,
and possibly parasitic plants (stariga, casccuta etc).
 They may be inoculated with viruses during feeding by insects or
by other vectors (insects/pest, water, air, humans etc).
 Plant pathogens have made many adaptations to enable them to
invade plants, overcome plant defense mechanisms, and colonize
plant tissues for growth, survival, and reproduction.
plant tissues for growth, survival, and reproduction.
 Pathogens accomplish these activities mostly through secretions of
chemical substances that affect certain components or metabolic
mechanisms of their hosts.
 Penetration and invasion, however, seem to be aided by or in some
cases be entirely the result of, the mechanical force exerted by
certain pathogens on the cell walls of the plant.

9. Defense system in Plants