hormones Flashcards
types of stimuli plants detect
exogenous and endogenous signals
tropic response
growth mechanism
ex. gravitropism
nastic response
turgor changes
ex. water movement
morphogenic
changes in basic metabolism
taxic
swimming mechanism
ex. flaggelated sperm
plant hormones
gibberellin, auxin, cytokinin, jasmonic acid, ethylene, abscisic acid
gibberellin/auxin
both influence growth, flowering and fruit development
gibberellin influences germination
abscisic acid
important for abscission and dormancy
plant hormones and humans
JA, Aspirin, indole 3 acetic acid, have anticancer activity and anti inflammatory activity
plant hormones and gut microbiota
have a symbiotic relationship
tropism
response resulting in curvature of organs toward or away from a stimulus
Darwin experiment
tip of shoot is removed and covered with cap. Showed that something in the shoot causes curvature
Boysen Jensen experiment
tip separated by permeable and inpermeable blocks,
shows that tip transmits signals to bottom
Went experiment
tip placed on agar block, where the block is placed affects curvature
auxin
promotes elongation of coleoptiles, responds to light
IAA
natural auxin that moves from tip to base
Acid growth hypothesis
when auxin is exposed to cell walls, break down of cell wall occurs, causing more water to enter and expand the cell.
other auxin functions
lateral and adventitous roots
herbicides for dicot weeds
auxin in seeds help to promote fruit growth
cytokinins
produced in actively growing tissues (roots, embryos, fruits)
acts with auxin (cell division and differentiation)
have anti aging effects, stimulate RNA and protein synthesis
mobilize nutrients
absence of cytokinins vs increase in cytokinins
absence - cells grow large and don’t divide
increase - shoot buds form
effect of increasing auxins
roots form
effect of auxins in shoot
lateral growth is inhibited
sources of cytokinin
microalgae, bacteria, fungi
gibberellins
many different types, produced mainly in seeds and young leaves
promotes plant growth, promotes flowering, opens stomata
all inhibited by abscisic acid
bolting
rapid growth of floral stalk, caused by gibberellins
abscisic acid
inhibits seed germination, induces storage protein synthesis in seeds
ethylene
responses to stress such as mechanical pressure
triggers fruit ripening (positive feedback process)
triple response of ethylene
plant becomes fat, curved, and short.
what causes leaf abcission
a change in the balance of auxin and ethylene
fruit ripening and ethylene
burst of ethylene production in a fruit triggers ripening process
effect of flooding on ethylene production
lack of oxygen causes production of ethylene
brassinosteroids
found in all plant tissues, similar to auxin, functions in growth, differentiation, and stress tolerance
jasmonates
small molecules derived from fatty acids that are produced in response to herbivory, pathogen invasion, and fruit ripening. It helps with regulation of nectar secretion
strigolactones
produced in roots in response to low phosphate concentration, promote apical dominance, help mychorizae, promote seed germination