MICR 3220 Lecture Notes - Lecture 13: Parasitoid, Parasitism, Middle Lamella
30 Dec 2015
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Necrotrophic organisms (bacteria and fungi that parasitize leaves) General features: necrotrophs kill tissue and feed on the tissue they kill. Benefits: kill tissue rapidly so plant doesn"t respond, they are right there when tissue is dead-don"t have to compete. Microbes digest food externally, pretty much are all non-readily, to moderately assumable. All microbes have production of extracellular enzymes to digest polymers (doesn"t make them necrotrophic). Enzymes that can degrade cell wall (cell wall degrading enzymes): certain ones can be shown to kill plant material simply through digestion. Plant cell wall adjacent; in between we have a region called the middle lamella (glue holding cells together, composed primarily of pectin). Primary cell wall-composed of cellulose, a group of polymers called hemicellulose (mostly things hold cellulose fibres together) and the pectin intermixed. Secondary cell wall-cellulose main structural component, hemicellulose holding that together, and lignin in between them which is a strengthening compound.
