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microbio 17-19
microbio 16-18
| Question | Answer |
|---|---|
| General characteristic of nematodes | body covered by cuticle digestive system - mouth, oesophagus, intestine, anus seperate sexes females are longer than males |
| Nematode nervous system | nerve rings four major nerves neurotransmitters |
| nematode major nerves | dorsal, ventral and 2 lateral |
| nematode secretory-excretory system | tubular two lateral canals open at ventral excretory pore paired glands open into pore secretions of glands - immunogenic |
| nematode digestive system | mouth pharynx/oesophagus, intestine, anus, cloaca |
| male nematode reproductive system | testis copulatory bursa spicules |
| female nematode reproductive system | 1 or 2 tubular ovaries uteri vulval flap |
| categories of female nematodes | oviparous viviparous ovoviviparous |
| nematode life cycle | egg - L1 - L2 - (L3) - L4 - L5 or adult, male and female - egg |
| Nematode routes of transmission | oral percutaneous transplacental transmammary |
| Trichostrongylidae | Site (s) abomasum, small intenstine direct lifecycle roundworms |
| Haemonchus | Barber's pole worm location: abomasum |
| Nematode treatment | size other worms present and what proportion effective drenches likely worm risk over the next few months level of worm contamination last drench groups used |
| Characteristics of an anthelmintic | spectrum of activity administration safety margin selective toxicity withdrawal period economical |
| Anthelmintic groups | benzimidazoles imidazothiazoles tetrahydropyrimidines macrocyclic lactones organophosphates heterocyclic compounds salicylanilides |
| Anthelmintic resistance | The heritable ability of a worm to survive a dose of anthelmintic which would normally be effective |
| Types of resistance | Single Double Multiple Side |
| FECRT | Faecal egg count reduction test comparison of faecal egg counts between an untreated control group and a treatment group |
| Other tests for anthelmintic resistance | In vitro tests egg hatch test larval paralysis and motility test larval development test larval feeding inhibition test adult development test |
| Double anthelmintic resistance | one genus of parasites is resistant to one class of anthelmintic, while another genus is resistant to another anthelmintic |
| Multiple anthelmintic resistance | a single genus of nematode is resistant to more than one anthelmintic |
| Side anthelmintic resistance | when parasites develop resistance to one anthelmintic they are resistant to other drugs in the same class |
| Pathogenic fungi | -may be obligate or non-obligate/faculatuve parasites - reduce quality and quantity of paint production - affect food safety and human health - increased cost of production |
| Pathogenic fungi morphology and phenotype | Macroscopic features: colony morphology, colour, margin and secondary metabolites Microscopic structures: mycelium and reproductive structures and spores |
| Classifying fungi (molecular taxonomy) | ITS: internal transcribes spacers nrDNA is the universal barcode of fungi MLSA: phylogenies based on multiple housekeeping loci WGS: phylogenic studies based on 100s of core genes |
| MLSA | Multi locus sequence analysis |
| WGS | Whole genome sequencing |
| Arbuscular mycorrhizal fungi (AMF) | form symbiotic relationships with plants, colonise the roots and increase the uptake of nutrients and resistance to biotic and abiotic stresses and in return, acquire nutrients from plants - obligate biotrophs |
| Mycorrhizal fungi - crop benefits | improved nutrient acquisition improved water absorption and better drought tolerance better resistance against biotic stresses decreased weed incidence |
| Soft rot (post harvest disease) | -rhizopus stonier causes soft rot in fruits - affects many crops and causes food spoilage aseptate mycelia asexual stage: sporangia and sporangiospores sexual stage very rare |
| Pathogenic fungi | -may be obligate or non-obligate/faculatuve parasites - reduce quality and quantity of paint production - affect food safety and human health - increased cost of production |
| Pathogenic fungi morphology and phenotype | Macroscopic features: colony morphology, colour, margin and secondary metabolites Microscopic structures: mycelium and reproductive structures and spores |
| Classifying fungi (molecular taxonomy) | ITS: internal transcribes spacers nrDNA is the universal barcode of fungi MLSA: phylogenies based on multiple housekeeping loci WGS: phylogenic studies based on 100s of core genes |
| MLSA | Multi locus sequence analysis |
| WGS | Whole genome sequencing |
| Arbuscular mycorrhizal fungi (AMF) | form symbiotic relationships with plants, colonise the roots and increase the uptake of nutrients and resistance to biotic and abiotic stresses and in return, acquire nutrients from plants - obligate biotrophs |
| Mycorrhizal fungi - crop benefits | improved nutrient acquisition improved water absorption and better drought tolerance better resistance against biotic stresses decreased weed incidence |
| Soft rot (post harvest disease) | -rhizopus stonier causes soft rot in fruits - affects many crops and causes food spoilage aseptate mycelia asexual stage: sporangia and sporangiospores sexual stage very rare |
| Ascomycota | largest phylum in kingdom of fungi diverse asexual stage sexual stage: ascocarps and ascospores septate hypae |
| Powdery mildews | obligate parasites cause disease and yield loss |
| Brown rot | moulina fructicola (ascomycota) dark necrotic lesions with irregular margin infection starts in orchard but disease appears post harvest (latent = quiescent) can result in mummified fruit |
| Blue mould | caused by penicillium species ascomycota |
| Gray mould | infection occurs at flower stage and remains quiescent until fruit ripens caused by botrytis species (ascomycota) |
| Basidomycota | second largest phylum of fungi many edible mushrooms well known pathogens are smuts and rusts basidiospores |
| Rusts | obligate parasites monoecious: one plant host heteroecious: complete life cycle on multiple plant hosts can have a range of spore types of only a few spore types |
| Wheat stem rusts | reddish brown spores in oval, elongated pustules on stems and leaves heteroecious and macrocyclic in EV but not AV only produces asexually in AV |
| Disease control interventions | reduce inoculum load limit pathogen dispersal reduce/prevent infection |
| Fungal disease management (cultural practices) | Crop rotation sowing time farm hygiene |
| Fungal disease management (biological control) | specific biocontrol agents promoting microbiome diversity in soil |
| Fungal disease management (chemical control) | fungicide application in field spraying |
| Fungicide resistance | overuse of fungicide unnecessary use of fungicide |
| Managing fungicide resistance | avoid susceptible cultivars rotate crops use non-chemical management methods to reduce disease pressure apply spray strategically rotate and mix fungicides with different modes of action |
| Phylum Nematoda | Most abundant group of multicellular animals on earth Small, non-segmented, worm-like organisms with transparent cylindrical bodies can be up to a few mm long |
| Losses in ag caused by plant parasites | 5-20% losses in agricultural production |
| Free-living soil nematodes | millions of individuals per square mm play a key role in biological processes such as nutrient mineralisation |
| Beneficial nematodes | enhance soil quality and nutrient cycling in the soil or control plant pests and plant parasitic nematodes |
| Plant parasitic nematodes | use their stylet to pierce plant cell wall and suck the cytoplasmic contents from plant cell |
| direct damage (plant parasitic nematodes) | cause damage directly by damaging the root and using up the nutrients |
| indirect damage (plant parasitic nematodes) | cause damage indirectly through transfer of viruses or by making plants more susceptible to disease |
| nematode feeding types | fungal feeder omnivores bacterial feeders plant parasite predator |
| plant parasitic nematodes life cycle | egg juvenile stage (J1) moult in egg (J2) J3 J4 Adult |
| Ectoparasites | feed from outside of the root use long stylet dagger nematodes needle nematodes |
| endoparasites | completely enter plant tissue migratory endoparasites, root lesion nematodes and stem and bulb nematodes sedentary endoparasites are the most damaging plant parasitic nematodes |
| semi endoparasites | partially enter plant tissue |
| soybean cyst nematode | cause poor growth, yellowing and stunting of soybean exotic plant pest (not present in Australia) |
| Root Knot nematodes (RKN) | sedentary endoparasites frequent pathogenesis J2 only infective stage females pear shapes, males worm like males are rare |
| Tomato root knot nematode | galls at point of entry plants show stunting, wilting, chlorosis of above ground plants |
| cereal cyst nematode | sedentary endoparasites cyst forming yellow patches of stunted plants reduced root system knots J2 infective |
| Root lesion nematodes | migratory endoparasitic nematodes impact grain crops (wheat, chickpea, canola) all stages except egg and J1 can be infective J4 optimal survival stage can overwinter in plant debris and soil |
| Disease complexes with soil borne pathogens | nematodes can have a synergistic effect due to: - utilisation of nematodes - induced wounds by soil borne pathogens -nematode induced physiological changes - modifications within rhizosphere |
| Annual ryegrass toxicity | poisoning of livestock that consume infected ryegrass infected by rathayibacter toxicus bacteria attach to cuticle of nematode and carry to inflourescents seeds replaced by nematode galls that contain the toxin producing bacterium |
| Control of nematodes | resistant and tolerant cultivars cultural practices chemical control biological control |
| Cultural control (nematodes) | cereal cyst nematode attacks: wheat, barley, oats, rye, wild oats, annual ryegrass use crop rotation: lipids, legumes, beans, peas use resistant and tolerant cultivars |
| What do all plant parasitic nematodes have in common? | 6 stages in their life cycle: Egg, J1, J2, J3, J4 and adult |
Created by:
sakelleher29
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