plant disease caused by nematode · nematode vectors of plant viruses-viral transmission occurs...
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Plant Disease Caused by Nematode
by Asst. Prof. Pornsuk Chaisuk
Kingdom : AnimaliaPlylum : Nematoda
- free living- plant/animal parasite
Types of nematode>100,000,000 species but only 20,000 species were named
Animal nematode 15%
Plant nematode 10%
Marine nematode 50%
Free-living nematode 25%
Animal and human nematodes
- Ascaris lumbricoides พยาธิในลาํไส/้พยาธิไสเ้ดือน- Trichinella spiralis พยาธิเนื�อหมู - Gnathostoma spiningenum พยาธิตวัจิ�ด- Ancylostoma duodenale พยาธิปากขอ (hookworm)- Wuchereria bancrofti สาเหตุโรคเทา้ชา้ง
Important plant nematodes
- Globodera rostochinensis : potato -> stunt
- Ditylenchus dipsaci : oat, rye, rice, onion, sugar beet
and other bulb plants -> bloat/
swollen
- Meloidogyne spp. : tomato, chilli, potato, caroot, okra,
soybean, grass and other plants ->
gall
History of nematode discovery
A.D.1656 : Nematode was first discovered after the invention of a microscope by P. borellus. First nematode was Turbatrix aceti (vinegar eel) that free living nematode lived in vinegar.A.D. 1743 : First plant nematode was discovered J.T. Needham. It was Anguina trtiici that lived in the swollen wheat seed.
History of important plant nematodes
Nematode Plant Discoverer Year
Anguina tritici wheat J.T. Needham 1743
Meloidogyne spp. cucumber M.J. Berkeley 1855
Ditylenchus dipsaci fuller’s teasel Julius Kuhn 1857
Heterodera schachtii sugar beet H. Schacht 1859
Globodera rostochiensis potato Julius Kuhn 1881
Father of nematology
Nathanial A. Cobb (1859-1932) is an important person for the study of nematodes in terms of discovering various types of nematodes. The invention of methods for the study of nematodes And being the creator of various words for use in nematology
Morphology of Plant Nematode
- Small size cannot be seen with the naked eye (approximately 250-1,200 micrometres in length, 15 micrometres in width) except in the cyst stage- The appearance is filiform liked eel shaped worms, except some genus in adult females stage- The body is unsegment and without appendages- Bilateral symmetry- Female cyst and some adult female have many shapes
Male
Female
Sedendtary endoparasites : Appearance1. Globodera sp. : body spherical,
forming cyst2. Heterodera sp. : body lemon-
shaped, forming cyst3. Meloidogyne sp. : body pear-
shape, no cyst4. Rotylenchulus sp. : body kidney-
shaped, no cyst
1
4
3
2
Sedentary endoparasites : Appearance
1. Cyst form (Globodera sp., Heterodera sp.) : dead female But there is still eggs inside2. Root knot nematode (Meloidgyne sp.) : lays eggs on the buttom outside the body, eggs are covered with gelatin “egg mass”
ovary
ovary
spicule
annules Lateral linestylet
anus
vulva
median bulb
excretory pore
esophagusintestine
Morphology of plant nematodes
Feeding of nematode
- free living : intracorporeal digestion
- plant parasite : extracorporeal digestion
Free living
Plant parasite
Nematode life cycle
1st molting
1st juvenile
egg
fertilization adult 4th molting
3rd molting
2nd molting
4th juvenile
3rd juvenile
Inside egg outside egg
2nd juvenile
Taxonomy of nematodes by Chitwood (1950)
Kingdom AnimaliaPlylum Nematoda : 2 class
1. Class Secernentea : phasmid present (phasmid is sensory organs at posterior)
2. Class Adenophorea : phasmid absent
Plant nematode- 95% in Class Secernentea
Order Tylenchida- 5% in Class Adenophorea
Order Dorylaimida
Classification of nematodes based on behavior
- classification of nematodes by host- classification of nematodes by feeding habits- classification of nematodes by movement
Classification of nematodes by host
1. Phytophages : plant2. Microbivore : bacteria3. Fungivore : fungi4. Omnivore : vertebrates, invertebrates5. Predators : other nematode6. Animal parasite : vertebrates, invertebrates7. Saprophyte
Classification of nematodes by feeding habits
1. Ectoparasitic nematode 2. Endoparasitic nematode3. Semi-endoparasitic nematode
Classification of nematodes by movement
1. Migratory parasitic nematode2. Sedentary parasitic nematode
Ectoparasitic nematode
Hoplolaimus
Criconemella
Helicotylenchus
Ditylenchus
Helicotylenchus spp. (Spiral nematode)
Hoplolaimus spp. (Lance nematode)
Criconemella spp. (Ring nematode)
Maize
Xiphinema spp. (Dagger nematode)
Endoparasitic nematode
Meloidogyne
Heterodera
Rotylenchulus
Male
Female
Meloidogyne spp. (Root knot nematode)
Female
Egg mass
Meloidogyne spp. (Root knot nematode)
Rotylenchulus reniformis (Reniform nematode)
Maize
Heterodera zeae (Cyst Nematode)
Soybean
Heterodera glycines (Cyst Nematode)
cyst
Potatocyst
Globodera rostochiensis (Gloden nematode)
Classification of nematodes by feeding habits movement and position
- Below ground migratory ectoparasites : Helicotylenchus spp., Hoplolaimus spp., Criconemella spp.,
Xiphinema spp., Longidorus spp., Trichodorus spp., Paratylenchus spp.- Below ground migratory endoparasites :
Pratylenchus spp., Radopholus spp.- Below ground sedmentary semi-endoparasites and endoparasites :
Rotylenchulus spp., Tylenchulus spp., Heterodera spp., Globodera spp., Meloidogyne sp., Nacobbus spp.
- Above ground endoparasites : Anguina spp., Ditylenchus spp., Aphelenchoides sp.
Pratylenchus penetrans
Trichodorus christiciHemicycliophora arenaria
Heterodera spp.Meloidogyne spp.
Nematode parasitism
1. Direct- wound- lack water and mineral- change plant physiology
2. Indirect- open the way for other microorganisms- nematode vectors of plant viruses
Mechanical for plant cell damage
1. Removal of cell contents2. Cell lysis3. Iduction of specialized feeding cells4. Systemic effects
Mechanisms for host disturbance by nematodes
1.1. No visible destructive effect
Migratory ectoparasites (short stylet): Root hair- Tylenchorhynchus spp.- Paratylenchus spp.
1.2. Immediate removal of cell contents
Migratory ectoparasites: Epidermis- Aphelenchoides spp.
1.3. Delayed removal of cell contents
Migratory and sedentary ectoparasites.: Cortex & Endodermis- Helicotylenchus spp.- Trichodorus spp.- Paratrichodorus spp.-Hemicycliophora spp.- Belonolaimus spp.- Ditylenchus myceliophagus
2.1. Progressive penetration
Migratory endoparasites: Cortex- Pratylenchus spp.- Radopholus spp.
2.2. Cell lysis
: Root tip & Meristem- Ditylenchus spp.
3.1. Nurse cells of Tylenchulus
3.2. Syncytium of Nacobbus
3.3. Syncytium of Heterodera
3.4. Giant cells of Meloidogyne
Sedentary parasites : feeding cells
Nurse cell Syncytium Giant cell
Interaction of nematodes with other microorganisms
1. Be vector of the other microorganisms.2. Make physical wound that the way for the other microorganisms.3. Make the leakage of attractants or nutrients that attract other plant pathogens to infect the plant.4. When plant cells die, the other microorganisms attack them repeatedly.5. Change plant physiology/biochemistry then plant is weak.
synergism = เสริมกนัantagonism = หักล้างกนั
Interaction of nematodes with virus
Virus can be transmitted by nematodes must# be seed borne and pollen borne# transmit by mechanical method
Types of nematode transmitted viruss
1. NEPO Viruses = Nematode Transmitted Polyhedral Shaped Viruses => # arabis mosaic virus
# strawberry latent ring spot virus transmitted by juvenile+adult of Xiphinema sp. &
Longidorus sp.2. NETU Viruses = Nematode Transmitted Tubular Shaped
Virus => # tobacco rattle virus# pea early browning virustransmitted by juvenile+adult of Trichodorus sp.
Nematode vectors of plant viruses
- Viral transmission occurs after the release of enzymes while the nematodes feed nutrients from plants.- virus don’t transmit to the nematode eggs.- No increase the amount of virus in the nematode.- After the molting, the virus will come out of the cuticle or in the small intestine.
Plant nematode diseases
1. Root galls or Root knots : Meloidogyne sp. induces root cells to begiant cells by hypertrophy and hyperplasia.
2. Root lesion : Pratylenchus sp. penetrates and migrates inside root tissue.
3. Stubby roots : Trichodorus sp. penetrates meristematic tissue of corn root then root is necrosis and stubby
4. Spring dwarf or Crimp : Aphelenchoides fragariae makes strawberry has many shoots; make lychee stunts; begonia leaf is brown and necrosis.5. White tip : Aphelenchoides besseyiinfects rice leaf tip.
6. Seed gall : ของขา้วสาลีและขา้วไรย์ เกิดจากไสเ้ดือนฝอย Anguina tritici infect wheat and rye seeds and live in infected seed for many year. One seed can have 800-32,400 nematodes.
7. Chrysanthemum leaf blight : Aphelenchoides ritzema-bosi is endoparasitic nematode, infect plant through guard cell.
Important plant nematode
Disease cycle of root-knot nematode Meloidogyne sp.
Life cycle 25 days
Disease cycle of the lesion nematode Pratylenchus sp.
Nematodes in root cortex
Lesions on peanut pods, Florida.
Disease cycle of the stem and bulb nematode Ditylenchus dipsaci
Life cycle 19-25 days
Ditylenchus dipsaci (Stem and bulb nematode)
Ditylenchus angustus
Rice Stem nematode
Disease cycle of the foliar (chrysanthemum) nematode Aphelenchoides ritzema-bosi
Life cycle 2weeks
Disease cycle of the stubby-root nematode Trichodorus christii
Life cycle 20 days
Nematode damage to corn roots
Plant nematode control
1. Cultural control- release flooding- soil solarization - leave the fields fallow- sanitation- crop rotation- applying manure, compost or green manure- using sterile seeds and seedlings- using resistant or tolerant varieties and rootstocks
2. Biological control- using nematode-toxic plants- using natural predators or pathogens of nematodes • antagonistic fungi : Purpureocillium lilacinum
(Paecilomyces lilacinus)• antagonistic bacteria : Pasteuria penetrans
3. Chemical control
Fumigants Non-fumigants
Methyl bromide Furadan
Dazomet Vydate
Mocap
Rubby
Nemacur