Plant Pathology Exam 2 (Chapter 9C and 11)

elicitor

Molecule produced by host that induces response to pathogen

pathogen density in which control is necessary to prevent it from reaching economic injury level to avoid significant economic loss

economic threshold

Receptor

protein that recognizes and responds to a specific signal molecule

resistant

having the ability to fight against

susceptible

prone to develop disease when infected

tolerance

development of disease would have little effect on overall yield

escape

lack of disease even when disease is prevalent

Pathogenicity

ability to cause disease

Virulence

degree of pathogenicity

avirulence

gene in a pathogen that causes defense reaction in a resistant host plant

immunity

cannot be infected

gene-for-gene interactions

specific response that makes particular plant genotypes resistant to particular parasite genotypes

H. H. Flor

Who was the first to describe gene-for-gene interactions in flax rust.

R genes

encode resistance traits

Avr genes

genes that code for elicitors

hypersensitive response

R gene resistance usually initiates which plant defense response

hrp genes

hypersensitive response and pathogenesis

bacteria

who has hrp genes

land races

A variety of species adapted to specific local conditions such as climate and soil type.

- only resistant against predominant pathogen

- Boom and Bust cycle (Late Blight of Potato)

- Qualitative

- single or few genes involved

- Also known as Vertical Resistance

- Strongest resistance

Specific resistance factors

- A number of genes can influence the pathogen

- Genetic Engineering

- Quantitative

- Polygenic (multiple genes)

- Also known as Horizontal Resistance

- Durable

General Resistance Factors

gene silencing

blocking or destroying mRNA in the gene in hopes it would no longer function

genetic engineering

A technology that includes the process of manipulating or altering the genetic material of a cell resulting in desirable functions or outcomes that would not occur naturally.

cross protection

protection against infection by more severe strains of the virus

Coat protein mediated resistance

Biotechnologists have introduced the gene for the coat protein from a virus into a host plant.

Transforming

introduces gene from pathogen to genome of host.

Ti plasmid

most commonly used vector for introducing new genes into plant cells using genetic engineering

gene gun

device used to shoot DNA-coated pellets into plant cells

protoplast

The contents of a plant cell exclusive of the cell wall.

Transgenic

contains genes from another species

CGIAR

Consultative Group on International Agricultural Research

Fort Collins, CO

where is the national seed bank in the USA

- interactions in the disease triangle

- what management tactics are available

- cost

- time

What should be considered when deciding on the appropriate management strategy

Avoidance focuses on the environmental component of the disease triangle. Pathogens can be avoided by choice of planting site, timing of planting, or resistant culivars.

PREVENTATIVE method

How do we avoid pathogens

management of plant diseases by preventing the introduction of pathogens in crop production areas.

How do we exclude pathogens

quarantine

restriction in the movement of plants, material, seed, soil, and machinery that would introduce a pathogen to new areas.

Plant Quarantine Act of 1912

The first US quarantine law

phytosanitary certificate

official document that indicates that plant material has been inspected and found to be free of certain pathogens

Remove or destroy pathogen before production of healthy plant can occur

Used to CONTROL and PREVENT against further stress.

How do we eradicate pathogens

- crop rotation

- fallowing

- flooding

- roguing

- plowing

- sanitation

Cultural Practice for Eradication

steam heat - usually in greenhouse

Solarization - traps solar radiation under plastic sheets

Hot-Water Treatment

Thermotherapy

Ways Heat can be used to eradicate

Protect against secondary inoculum

How do we protect plants

disinfectants

herbicides

insecticides

nematicides

fungicides

What are some chemical methods to protect

LD50

the amount of a chemical that kills 50% of the animals in a test population

green manure

Freshly cut or still-growing green vegetation that is plowed into the soil to increase the organic matter and humus available to support crop growth.

hyperparasites

parasites of parasites does not include nematodes

Predation

predaceous nematodes feed on plant-pathogenic nematodes and eggs

hypovirulence

Mechanism of biocontrol utilizing reduced virulence of a pathogenic (usually fungal) strain due to the presence of transmissible double stranded RNA ("mycovirus")

Pyramiding

stacking of different genes to achieve resistance - also used in backcross breeding

offers flexibility cause breeders can add or subtract R genes - Good for genetic variation

How might multiline and mixture planting techniques be effective disease management