Exam #1 Flashcards
sustained physiological and structural issue that affects some or all plant processes
plant disease
series of steps to isolate and determine what causes a disease; cannot be done with every disease
Koch’s Postulate
fungi, bacteria, viruses, and nematodes
biotic agents
non-bio factors (climate, mechanical)
abiotic agents
obtain nutrients from dead organic matter
saprophytes
organism that grows inside the plant to complete its lifecycle and therefore has a detrimental affect on the plant
plant pathogen
obtain nutrients from another organism
parasites
need a host to live; only gets nutrients from living material
biotroph/obligate parasite
kill host and then take nutrients
necrotroph
feed on living and/or dead tissue; usually asymptomatic at first, later turns to killing tissue
hemibiotrophs
live on dead organic matter ONLY; decomposers
obligate saprophytes
better adapted as parasites, but can live as a saprophyte; adopted the ability to feed on dead OM
facultative saprophyte
better adapted as saprophyte, but can survive as a parasite when needed; adopted ability to be a parasite
facultative parasite
external/internal reactions of a plant caused by the disease - galls, leaf spot
symptom
pathogen itself shown on the plant - rust spores, powdery mildew
signs
environment, pathogen, and host (also time)
disease triangle
plant cannot be infected
immune
plant can be infected
suceptible
plant may be infected, but won’t allow pathogen to proliferate
resistance
plant can be infected and disease can spread, but the plant will survive
tolerant
order of disease development
- dispersal of pathogen to host
- penetration and infection of host
- invasion and colonization of host
- reproduction of pathogen
- dispersal of new host
- pathogen survival over winter
steps in life cycle that lead to disease
disease cycle
structure/part of pathogen that starts the infection
primary inoculum
method through which a pathogen gains access to a host - spores, insect transport
dispersal of inoculum
location where the infection starts
infection court
process of successfully infecting a host
colonization
produced on an infected plant that can lead to new infections during the same growing season
secondary inoculum
complete only 1 cycle of development (only primary inoculum) - reduce the amount/efficiency of primary inoculum to manage
monocyclic
complete more than 1 cycle of development (primary and secondary inoculum) - reduce primary inoculum and reduce the rate of secondary infections; only controlling primary doesn’t do much - **sigmoid curve
polycyclic
don’t bring pathogen to the host - time when inoculum isn’t present - take out 1 of the categories in the disease triangle
avoidance
prevent the introduction of the pathogen; quarantine; plant seed is free of pathogen before planting (seed indexing)
exclusion
destroying disease by removing infected material; solarization to kill pathogen
eradication
chemical, biological, and cultural practices to prevent infection and disease
protection
closer relatives to animals (glycogen, chitin in cell walls), eukaryotic, haploids
fungi
sexual spores produced in asci (sacs); septate hyphae generally with two haploid nuclei in each cell; 8 ascospores
ascomycetes
sexual spores produced in basidia (club-shaped); 4-spore cells; hyphae with 2 haploid nuclei in each cell; clamp connection
basidiomycetes
fungus-LIKE organisms; water molds; absorb nutrients thru cell walls with cellulose; have hyphae; feed on decaying matter
oomycetes
motile spores that swim thru water to sear for food; 2 flagella with different structures and functions
zoospores
filamentous vegetative bodies branching out in all directions (hyphae = individual branches)
mycelium
roles of hyphae
nutrient acquisition, penetration, networking, survival structures, proliferation, mating, fusion, and fruiting body production
nutrient acquisition and growth are related (hyphae must move towards food)
trophic growth
reproduce by budding; no hyphae; single cells
yeast
bulb outside the infection zone of hyphae
appresorium
specialized fungal hyphae that penetrates cell walls and expands inside the cells; nutrient acquisition and interaction between fungi and the host; surrounded by the host cell membrane; only penetrates thru the cell wall
haustoria
neighboring hyphae fuse together for circulation and important for mating
hyphal fusion
self fertilization (uniform)
homothallic
out-crossing fungi (diversity)
heterothallic
specialized hyphae; holds spores and produces and releases them; sexual or asexual
fruiting bodies
classic mushrooms - few are pathogens
basidiocarps
morels and small fruiting bodies
ascocarps
formed under adverse conditions (host, climate, pH); perennial fruiting bodies can last for several years
survival structures
hardened masses of hyphae that contain fruiting bodies
stroma
masses/balls of hyphae that can stay for several years; dark in color because it has melanin to protect it from the sun
sclerotia
melanized hyphal ropes
rhizomorphs
hyphae that fully encases the host tissue
mummies
wind, water, and vectored dispersal
passive dispersal
motile spores, forceable ejection
active dispersal
hyphae that produces spores without the genetic variation
conidiophores
fungal disease cycle
- dissemination/ transmission
- arrival and attachment
- infection
- colonization
- survival
from one unrelated host to another
horizontal transmission
from parent to progeny
vertical transmission
infect directly thru the cell walls of a host
direct penetration
fungi can induce plant defense response that’s harmful to itself - air bubbles (tyloses) to prevent fungus from spreading
autotoxicity
stimulate host to produce growth hormones leading to deformities - more to feed on for parasite
growth deformity
where exclusion, eradication, and avoidance is highly effective
facultative saprophytes and obligate parasites
where exclusion, eradication, and avoidance isn’t as effective - use protection!
facultative parasites
microscopic non-segmented round worms
nematodes
can determine whether it’s parasitic or not (nematodes) - parasitic have these
stylets
nematode life cycle
egg –> 4 juvenile stages –> adult
infection occurs during juvenile 2 stage
