Immunity
protein can trigger responses that can prevent disease
Pathogens are those life forms that attack
from affecting the plant.
and damage our plants. Pathogens have difA pathogen-encoded effector is a protein secreted
ferent strategies for surviving and thriving
by a pathogen and it works to help the pathogen
within the plant—bacterial pathogens, for
adjust to its new living environment within the
instance, proliferate in the spaces between
host plant—sort of like the Trojan horse. The plant
the cell walls. They often get started by
has a counter move to this attack,
entering through a gas pore
however, as the introduction of an
(stomata) or a water pore (hyeffector often triggers the activation
dathode) and of course they
of a disease-resistant protein within
can enter through a wound
the plant. The ‘R’ protein recognizes
as well. Some other plant inthe modified version of the plant
vaders are aphids and nema“Pathogens have different
caused by the effector in a similar
todes—which insert their litstrategies for surviving and
way to the ‘danger signal’ models
tle stylets into plant cells—and
thriving within the plant.”
that kick into action in a mammal.
fungi, which have many ways
The war goes on.
to get under the protective
There are two basic branches of
skin of your plants. There are
plant immune systems—one uses
many types of pathogens that
transmembrane pattern receptors (PRRs) that respond to
try to use, feed off of or injure plants; without some system
the slowly evolving changes caused by microbial- or pathof defending themselves plants would be unable to survive.
ogen-associated molecular patterns (MAMP or PAMP).
To obtain a basic understanding of these plant defense
The other acts mostly inside the cell, using protein prodprocesses you’ll need to add a few terms to your vocabuucts activated as the result of some effector.
lary: disease-resistance proteins (R), pathogen-encoded efThe thin black arrows indicate the ongoing level of plant
fectors (PE), transmembrane pattern-recognition receptors
immunity. In the first phase, the plant detects the initial
(PRR), microbial-associated molecular patterns (MAMP)
effectors from the microbial or pathogen-associated moand pathogen-associated molecular patterns (PAMP).
lecular pattern (MAMP or PAMP) and triggers increased
In order for a disease-resistant plant protein to be effecresistance and immunity (PTI) for