Nematodes
Download
1 / 56

Nematodes - PowerPoint PPT Presentation


  • 360 Views
  • Uploaded on
  • Presentation posted in: General

Nematodes. Nematodes are extremely abundant and diverse. Variable size: 0.2 mm to over 3 m Found in virtually all the ecosystems. Over 20,000 species have been described. Numerically extremely dominant, over 80% of all living animals on earth are nematodes! Grouped into a phylum “Nematoda”.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

Nematodes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript



Nematodes are extremely abundant and diverse
Nematodes are extremely abundant and diverse

  • Variable size: 0.2 mm to over 3 m

  • Found in virtually all the ecosystems.

  • Over 20,000 species have been described.

  • Numerically extremely dominant, over 80% of all living animals on earth are nematodes!

  • Grouped into a phylum “Nematoda”


Nematodes

Figure 2. The relationships of the Nematoda.

Blaxter M (2011) Nematodes: The Worm and Its Relatives. PLoS Biol 9(4): e1001050. doi:10.1371/journal.pbio.1001050

http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001050




Nematodes

Cyst Nematodes (Heterodera & Globodera)

Root-Knot Nematodes (Meloidogyne)

Sedentary endoparasites

Family Heteroderidae




Nematodes

Life cycle cyst nematode

Six stages (egg, 4 juvenile stages, and adult)



Hatch
Hatch cyst nematode


Nematodes

J-1 occurs in the egg cyst nematode




Gland cells
Gland Cells cyst nematode


Nematodes

- Extensive endoreduplication cyst nematode

- Increased cytoplasmic density

- Cell wall degradation

- Breakdown of large vacuoles

- Increased numbers of organelles

- High metabolic activity


Nematodes

Feeding Sites cyst nematode

Syncytium

Giant-Cells

  • Fused cells

  • Dense cytoplasm

  • Cell wall changes

  • No nuclear division

  • No cell division

  • Discrete and enlarged cells

  • Dense cytoplasm

  • Cell wall changes

  • Nuclear division without cytokinesis

  • No cell division


Nematodes

Giant-Cells cyst nematode


Nematodes

Giant-Cells cyst nematode


Nematodes

Syncytium cyst nematode



Nematodes

Parasitism Genes: Nematode Effectors cyst nematode

The genetic determinants that enable a nematode to infect plants

  • Parasitome

ParasitismGenes

Parasitism Proteins


Nematodes

SCN Cellulases cyst nematode

in situ hybridization

Construction of gland-specific cDNA libraries

Microaspiration of esophageal gland cell cytoplasm

1-Signal peptide prediction

N-terminal sequence that targets proteins to ER and the secretory pathway

MNWMHYCLIACFSIYYFNTVESSTINSVTVQVNKIENNEKGRQFNLKFTNQVYERVCHVDFRVDLPDTAKLDKYSKMVPIPDTCGQYALPKSLDLLPGETFDAQLTLLGHDGKPNVTVLNTNNIPTSKQCKK-

2-Gland-specific expression


Nematodes

3-High expression level during parasitic stages cyst nematode

Developmental expression profile of CBP in H. schachtii

These criteria allowed the identification of more than 50 putative parasitism proteins

Huang et al. MPMI Vol. 16, No. 5, 2003, pp. 376–381.

Gao et al. MPMI Vol. 16, No. 8, 2003, pp. 720–726.


Nematodes

Evidences for Secretion cyst nematode

-Enzymes without substrates (cellulase and pectinase)

-Enzymes without pathway (chorismatemutase, shikimate pathway) Putative Function Assignment

-Similarities are with other parasitic nematodes, bacteria, fungi or plants but not with proteins from C. elegans



Nematodes

1-Developmental expression profile Nematode Effectors

High expression level during parasitic stages


Nematodes

2-in situ Nematode Effectors hybridization

Detection of 10A7 mRNA in dorsal gland cells

mRNA in situ hybridization of a cellulase probe to transcripts expressed specifically within the two subventral esophageal gland cells


Nematodes

3-In Nematode EffectorsPlanta Localization of effector Proteins

Cellulase secretion into root tissue around the head of a J2

Wang, et al. 1999; 12:64-67


Nematodes

Secretion of cellulase (green fluorescence) associated with cell wall degradation along the migratory path of the J2

Wang, et al. 1999; 12:64-67


Nematodes

4 Intracellular cell wall degradation along the migratory path of the J2localization of the effectors

Plasma membrane

Cytoplasmic

Nuclear


Nematodes

5-Plant Expression of Parasitism Genes cell wall degradation along the migratory path of the J2

Transgenic Arapidopsis expressing a nematode Clavata3-like gene showing an arrested shoot apical meristem

Wang et al.,, Molecular Plant Pathology 2005;6:187-191.

C24

CBP

Expression of a nematode parasitism gene in plant tissues stimulated root growth


Nematodes

5-Plant Expression of Parasitism Proteins cell wall degradation along the migratory path of the J2

WT

10A06ox

WT

10A07ox

32E03ox

WT


Nematodes

6-Mutant Complementation cell wall degradation along the migratory path of the J2

Chorismate mutase complementation

CLV3 Complementation

minimal medium without supplemental phenylalanine and tyrosine

A CM deficient E coli strain transformed with a plasmid containing CM coding region was streaked on the top half of the petri dish The same CM-deficient E. coli strain containing only the plasmid was streaked at the bottom half of the plate (Vector)

A fully restored clv3-1 mutant expressing nematode CLV3-like gene

Arabidopsis wild-type

Arabidopsis clv3-1 mutant

Lambert et al. MPMI, 1999; 12:328–336.

Wang et al.,, Molecular Plant Pathology 2005;6:187-191.


Nematodes

7-Gene Silencing cell wall degradation along the migratory path of the J2

Plant host-derived RNAi is used to silence the expression of the parasitism genes

Expression of 16D10 dsRNA in Arabidopsis resulted in resistance effective against the four major RKN species

Huang et al. (2006)103:14302-14306.


Nematodes

8-Determination of Nematode Susceptibility cell wall degradation along the migratory path of the J2

Enhanced nematode susceptibility in the transgenic plants expressing nematode effectors


Nematodes

Prey cell wall degradation along the migratory path of the J2

Prey

Spermidine Synthase (SPDS1)

Spermidine Synthase (SPDS2)

Bait

10A06

Lamin C

Hs-RFCP Lamin C Vector

Vector

SD/-Leu/-Trp

SD/-Leu/-Trp/-Ade/-His

BiFC assay

Bright Field

Bait

Hs-RFCP

YFP

Lamin C

Vector

SD/-Leu/-Trp

SD/-Leu/-Trp/-Ade/-His

Overlay

9-Search for Interacting Proteins

10A06 interacts specifically with Spermidine Synthase 2


Nematodes

10-Characterization of the interacting proteins cell wall degradation along the migratory path of the J2

Promoter lines, Overexpression, Mutant Lines, …

4 dpi

7 dpi

14 dpi

Pro-PK

Pro-IAA16


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2


Nematodes

Functions of Parasitism Proteins cell wall degradation along the migratory path of the J2

Nematodes need to penetrate and migrate through the roots !

1- Cell wall-digesting enzymes

Cellulase (Obtained from either bacteria or fungi by HGT)

Pectinase

Cellulose-binding protein

Expansins


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

Nematodes need to change plant metabolism in the infected cells!

2-Metabolic Pathway Enzymes

ChorismateMutase


Chorismate mutase cm

Shikimate cell wall degradation along the migratory path of the J2Pathway

Chorismate

Tryptophan

CM

Tyrosine

Phenylalanine

Prephenate

Functions of Nematode Effectors

Chorismate Mutase (CM)


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

Nematodes need to alter plant cell development?

3-Small bioactive peptides

CLAVATA3-like peptide

Unknown peptide < 3KDa


Nematodes

CLV3 cell wall degradation along the migratory path of the J2

CLV3

CLV3

CLV1

CLV1

P

P

P

P

P

P

P

P

P

P

Functions of Nematode Effectors

Model for CLAVATA3 Action

CLV1

Signal transduction leading to developmental changes

Does the cyst nematode use ‘ligand mimicry’ to alter plant cell development?


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

SCN SYV46 functions as CLAVATA3

clv3-1 mutant

SYV46 in clv3-1

wild-type

Does the cyst nematode use ‘ligand mimicry’ to alter plant cell development?


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

4-Auxin signaling

Lee et al., 2011. Plant Physiology

Cyst nematode effector 19C07 interacts with the Arabidopsis LAX3 auxin influx transporter


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

5-Suppression of host defenses

Polyamine biosynthesis

An effector 10AO7 specifically

interacts and induces SPDS2

activity and alters spermidine

level.


Nematodes

Functions of Nematode Effectors cell wall degradation along the migratory path of the J2

Nematodes need to cell cycle activities in parasitized plant cells

6-RanBPM

Secretory protein with high similarity to proteins binding to the small G-protein Ran


Nematodes

7- Control of Transcriptional Machinery cell wall degradation along the migratory path of the J2

A Meloidogyne incognita effector is imported into the nucleus and exhibits transcriptional activation activity in planta

Molecular Plant Pathology30 JUN 2014 DOI: 10.1111/mpp.12160http://onlinelibrary.wiley.com/doi/10.1111/mpp.12160/full#mpp12160-fig-0005


Nematode resistance genes
Nematode Resistance Genes cell wall degradation along the migratory path of the J2


Nematodes

The cell wall degradation along the migratory path of the J2Rhg4 locus has a gene encoding serine hydroxymethyl transferase (SHMT)

Functional validation of SHMT

by VIGS, RNAi and complementation.

SM Liu et al.Nature000, 1-5 (2012) doi:10.1038/nature11651

Note: This figure is from a near-final version AOP and may change prior to final publication in print/online


Copy number variation of multiple genes at rhg1 mediates nematode resistance in soybean
Copy Number Variation of Multiple Genes at cell wall degradation along the migratory path of the J2Rhg1 Mediates Nematode Resistance in Soybean

Cook et al.,Science 30 November 2012:vol. 338 no. 6111 1206-1209


Nematodes

Broad Resistance of Mi-1 Gene cell wall degradation along the migratory path of the J2

resistance to the root-knot nematode Meloidogyne incognita

Resistance to the potato aphid Macrosiphum euphorbiae


ad
  • Login