Studied by 22 people
plant hormones
produced by special cells & influence physiology of cells
most common hormone
auxin (IAA)
auxin (IAA)
promotes plant growth by facilitating elongation of developing cells
where is auxin produced?
@ root & shoot tips (apical meristems)
how does auxin lead to growth?
increases H+ ion --> loosens primary cell wall --> wall expands due to increased turgor pressure
gibberellins (gibberellic acid)
group of plant hormones that promote cell growth; 2nd-most common
how many variations do gibberellins have?
60 variations (GA1, GA3)
where are gibberellins produced?
in young leaves, roots, & seeds but may be transported to other plant parts
how do gibberellins cause growth?
increase levels of GA --> rapid shoot growth (bolting)
cytokines
group of hormones that stimulate cytokinesis (division of cytoplasm)
produces lateral (horizontal) growth & delays senescence (aging) of leaves
cytokines are a variation of...
nitrogen base adenine
where are cytokines produced?
in roots & transported throughout plant
what are cytokines often coupled w/?
coupled w/ auxin
ethylene
gas that promotes ripening of fruit & stimulates production of flowers
ethylene + auxin -->
inhibits lengthening of roots, stems, & leaves
why is the role of ethylene opposite of cytokines?
ethylene influences leaf abscission (dropping of leaves)
abscisic acid (ABA)
growth inhibitor
what is abscisic acid role in buds?
delays growth & causes formation of scales
what is abscisic acid role in seeds?
maintains seed dormancy
what is dormancy interrupted by?
interrupted by gibberellins
Note
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