Related to Parasitomes and Nematode-Plant interaction.

2. PARASITOMES
• Muhammad Subhan Shafique
• 7th Semester
• Department of Plant Pathology

3. WHAT ARE PARASITOMES?
• Proteins which are secreted from the stylet of the nematodes and
are successfully involved in the parasitism of the plant cells are
called “parasitomes”, a subset of the secretome (secreted
proteins) of a parasite that mediates parasitism.
• These stylet secretions are directly involved in the infection and
parasitism of the plants.

4. NOTE
• The first characterized parasiotme was
β-1, 4-endoglucanases (Cellulases)
secreted by two subventral glands of the
cyst nematodes Heterodera glycines and
Globodera rostochiensis. They were
present only in the motile phases of
nematodes i.e infesting and pre-infesting
larvae and male.

5. TYPES OF ESOPHAGEAL GLANDS
The esophageal glands are of two types:
• Dorsal gland
• Subventral gland
• These glands are involved in the synthesis
of these secretions (Parasitomes or
secretomes).

6. Diagram of the esophageal glands in the body of a motile second stage juvenile (A) and an adult female (B)
of a typical sedentary plant parasitic nematode.

7. Presence of secretory granules within the dorsal gland lobe and along the extension of the
ampula.
A B
DG
DG

8. RKN stylet secretions. Stylet secretions (arrow) of a second stage M. incognita juvenile visualized after Coomassie
staining (a). The RKN calreticulin protein (arrows) detected in planta at the tip of the stylet of a female (~) and along
the cell wall of adjacent giant cells (*).

9. FUNCTIONS OF
THE
PARASITOMES
The stylet secretions are thought to be
involved in:
 Cell wall degradation
 Protection against the plant defense
responses
 The induction of giant cells

10. EXAMPLES
• The effector proteins include:
• CLV3
• SPRY domain-containing (SPRYSEC) effector proteins
• Mi-EFF1
• Calreticulin Mi-CRT
• Hs19C07
• These proteins are involved in plant-nematode compatible interactions
by suppressing the defense mechanisms of host plants in some cases.

11. PARASITISM GENES
• The genes of effector proteins (Parasitomes) are called “Parasitism
genes”.
• Secretome contains products of diverse parasitism genes.
• To date over 100 of parasitism genes have been cloned, the host targets
and functions of several of the secreted effector proteins have been
explained i.e 51 gland expressed candidate parasitism genes from H.
glycines and 486 proteins by M. incognita (by using spectrometery).

12. ENZYMES IN PARASITOMES
• Secretomes/Parasitomes contain products of diverse Parasitism
genes.
• The genes encode for pant cell wall degrading/modifying enzymes
including:
• β-1, 4-endonucleases
• Cellulases
• Chitinases
• Xylanases
• Pectate lyses

13. CONTINUE……
• These cell wall degrading enzymes help the infective juvenile 2
nematodes to migrate through plant roots by softening in the cell wall.
• They degrade the cellulose, hemi-cellulose or pectin and proteins that
bind cell wall components.
• The effector proteins suppress the defense mechanism of host-plants in
some cases.

14. EXAMPLES
Compound Nematode species Possible Function
1-4 endonucleases (Cellulases) G. rostochiensis, G. Pallida,
G.tobacum, H. glycines, M.
incognita.
Cell wall degradation (CWD)
Pectate lyase M. javanica, M. incognita,
H. glycines.
CWD
Thyroxidin peroxidase G. Rostochiensis Peroxide destruction,
protection against host.
Cellulose binding protein
(СВР)
M. incognita, H. schachtii, H.
glycines
Cell wall modification
Polygalacturonase M. incognita CWD
Fatty acid and retinol
binding protein
Globodera pallida Protection against plant
defense response