Succession, the gradual and continuous change in species composition and community structure over time.

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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

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#Unit 6. System Physiology – Plant

TLS Online TPP Program

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#Unit 6. System Physiology – Plant

Biotrophic fungi usually penetrate the rigid cell wall via the formation of a specialized infection structure on the plant

surface called an appressorium. Then, the emerging penetration

peg breaches the rigid plant cell wall and provides entry into the plant cell. Finally, a haustorium forms upon entry into the plant cell.

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#Unit 6. System Physiology – Plant

Necrotrophs are Opportunistic, unspecialised (‘non-obligate’) pathogens and Host cells killed rapidly

Entry unspecialised via wounds or natural openings

Secrete copious cell-wall-degrading (lytic) enzymes and toxins

Appressoria/haustoria not normally produced

Wide host range

Easy to culture axenically

Survive as competitive saprotrophs

Controlled by jasmonate- and ethylene-dependent host-defence pathways

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#Unit 6. System Physiology – Plant