It is about mechanism of nematode-induces plant resistance.

1. Understanding the Mechanisms
of Nematode-Induced Plant
Resistance

2. Nematode- Induced Plant Resistance
Nematode – Induced Plant Resistance refers to the defense
response exhibit by plant against nematode infestation.
 Nematode are microscopic, worm like organism that can be both plant parasite
and pathogens.
 When they infect plant , plants trigger a series of defense response to protrect
themselves from invaders.
 These defense mechanisms can be classified into two main categories :
1) Pre- formed defense
2) Induced defense

3. Preformed defenses
1. Physical barriers: Some plants possess thick cell walls and additional
layers of tissue in their roots, making it harder for nematode to penetrate and
feed on plant cells. By reinforcing their cell walls with lignin, suberin, or
callose, plants can fortify their roots and reduce the damage caused by
nematode feeding.
3. Endophytes : Some plants form symbiotic relationships with beneficial
fungi or bacteria that can protect them from nematodes
2. Chemical Compounds: Plants synthesize various defense molecules in
response to nematode infestation. These molecules include phytoalexins,
which are antimicrobial compounds toxic to nematodes, and reactive oxygen
species (ROS), which can damage nematode tissues.

4. Induced defenses
1) Hypersensitive response (HR)
 Hypersensitive
response, causing
localized cell death
around the nematode
feeding site. This
prevents the spread
of the nematodes to
other parts of the
plant.
As a result of the HR, the plant cells surrounding the nematode feeding
site undergo programmed cell death (PCD). This localized PCD leads to the
formation of necrotic lesions, which limit the nematodes access to nutrients
and help contain infection.

5. [Peter Balint-Kurti
et al., 2019]
T he virulence factors target certain cellular proteins that they modify
and this modification is then sensed by NLRs

6. 2) Systematic Acquired Resistance (SAR)
In response to nematode attack, plants can produce signaling molecules
such as salicylic acid, jasmonic acid which can travel through the plant
and induce resistance in distant tissues.
Jasmonic Acid and Salicylic Acid Pathways: JA and SA are signaling
molecules that activate specific defense response in plants. The JA pathway
is typically associated with defense against herbivores or nematodes, while
SA pathway is involved in defense against biotrophic pathogens. The
interplay between these pathways helps orchestrate the plant defense
response.

7. Jasmonic Acid Pathway
Here's how the pathway is involved in defending against nematodes:
2) JA biosynthesis
3)JA perception and signaling
4)Activation of defense genes
5) Expression of defense-related genes
6)Induced defense responses
1)Nematode infestation

9. 3) Pathogenesis Related - Protein
Pathogenesis-related (PR) proteins and antimicrobial peptides (AMPs) are
a group of diverse molecules that are induced by phytopathogens as well
as defense related signaling molecules.
 After pathogen challenge, activation of defense signaling
pathways viz., salicylic acid (SA) and jasmonic acid (JA) take place which
further leads to the accumulation of PR proteins that minimises pathogen
load or disease onset in uninfected plant organs.
In general, there are two types of pathogens viz., biotrophic and
necrotrophic, the first one activates the SA pathway that stimulates the
transcription of NPR1 (non-expressor of pathogen-related gene 1)
which in turn leads to activation as well as accumulation SA signature
gene (PR1, PR2 & PR5) products locally as well as systematically
leading to systemic acquired resistance (SAR). The SAR provides
enhanced resistance to a wide range of pathogen.

10. The second i.e., necrotrophic pathogen stimulates JA pathway that
induces the activation JA signature genes (PR3, PR4 & PR12) and leads to
accumulation of their product locally, and hence provides only local
acquired resistance (LAR).

11. Scheme of the pathways induced during the plant response to nematode
infection.
PR proteins –
pathogen-related
proteins, SA –
salicylic acid, JA –
jasmonic acid, ET –
ethylene, R gene –
plant resistance
gene, avr-gene –
gene encoding an
RKN avirulence
factor, MAPKs -
mitogen-activated
protein kinases,
PAMPs - pathogen-
associated molecular
patterns