BSC 196 Lecture Notes - Lecture 30: Water Potential, Circadian Rhythm, Thigmotropism
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The first li(cid:374)e of i(cid:373)(cid:373)u(cid:374)e defe(cid:374)se depe(cid:374)ds o(cid:374) the pla(cid:374)t"s a(cid:271)ility to re(cid:272)og(cid:374)ize pathogen- associated molecular patterns (pamps) Effectors are pathogen-e(cid:374)(cid:272)oded protei(cid:374)s that (cid:272)ripple the host"s innate immune system. The hypersensitive response: causes cell and tissue death near the infection site. Induces production of enzymes that attack the pathogen. Stimulates changes in the cell wall that confine the pathogen. Heat-shock proteins help protect other proteins from heat stress. Altering lipid composition of membranes is a response to cold stress. Freezing causes i(cid:272)e to for(cid:373) i(cid:374) a pla(cid:374)t"s (cid:272)ell walls a(cid:374)d i(cid:374)ter(cid:272)ellular spa(cid:272)es. Many plants, as well as other organisms, have antifreeze proteins that prevent ice crystals from growing and damaging cells. Salt can lower the water potential of the soil solution and reduce water uptake. The photoreceptors responsible for the opposing effects of red and far-red light are phytochromes. Circadian rhythms are cycles that are about 24 hours long and are governed by an internal (cid:862)(cid:272)lo(cid:272)k(cid:863)
