plant hormones

briggs experiment

split stem tip with glass to show how auxin moves across stem tip and away from light

blue light

phototropism responds, stomatal openings respond, green light switches response off

gravitropism

inhibitor in root cap, negative in shoots, positive in roots, statoliths, starch sheath cells, cytokinin in root cap

statoliths

gravity sensors

starch sheath cells

surrounds vascular tissues, continues in roots with endodermis

thigmotropism

differentiate growth on inside and outside of tendril, nyctinastic movements, thigmonastic movements, thigmomorphogenesis

nyctinastic movements

up and down movements in response to daily rhythms

thigmonastic movements

leaves open and close, ion fluxes at action potentials, mimosa plant

thigmomorphogenesis

gene expression induced by touch, suggests role for calcium in growth response

heliotropism

base of inflorescence has ion influxes that change direction towards sun, sunflowers

photoperiodism

response to duration of timing of day and night, day neutral means no critical value, run by phytochrome photoreceptor, dormancy

phytochrome photoreceptor

red and far red photoreceptors, light absorbing chromophore, flowering regulation

flowering regulation

photoperiod, gibberellins, hypothetical florigen, genetic control, FLC

hypothetical florigen

found mRNA flowering time and FT protein

FLC

flowering locus control, inhibits flowering, major determinant of meristem competence