In birds, primary neurulation generates the neural tube anterior to the hindlimbs.

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#Unit 6. System Physiology – Plant

Four major pathogens infects plants most frequently

1. Viruses

2. Bacteria

3. Fungi

4. Insects

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#Unit 6. System Physiology – Plant

Late blight disease (A), caused by the oomycete pathogen Phytophthora infestans

Black stem rust, which results from infection by the basidiomycete Puccinia graminis

Global banana (Musa spp.) production is under threat from black Sigatoka disease Mycosphaerella fijiensis.

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#Unit 6. System Physiology – Plant

An effector molecule is

made by a pathogen to enhance the pathogen’s colonizing

abilities.

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#Unit 6. System Physiology – Plant

Plant pathogens are divided into three groups

Biotrophs derive energy from living cells, they are found on or in living plants, can have very complex nutrient requirements and do not kill host plants rapidly;

Necrotrophs derive energy from killed cells; they invade and kill plant tissue rapidly and then live saprotrophically on the dead remains;

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#Unit 6. System Physiology – Plant

Hemibiotrophs have an initial period of biotrophy followed by necrotrophy.

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#Unit 6. System Physiology – Plant

Biotrophs are Specialised (‘obligate’) pathogens

Possess appressoria or haustoria

Narrow host range

Controlled by salicylate-dependent host-defence pathways