Plant Hormones

Created by kateylederer 

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Auxin (IAA)

Shoot apical meristems and young leavves are the primary sites of auxin synthesis.

Auxin (IAA)

Root apical meristems also produce auxin, although the root depends on the shoot for much of its auxin

Auxin (IAA)

Developing seeds and fruits ocntain high levels of auxin, but it is unclear whether it is newly synthesized or transported from maternal tissues

Auxin (IAA)

Stimulates stem elongation (low concentration only)

Auxin (IAA)

promotes the formation of lateral and adventitious roots

Auxin (IAA)

regulates development of fruit

Auxin (IAA)

enhances apical dominance

Auxin (IAA)

functions in phototropism and gravitropism

Auxin (IAA)

promotes vascular differentiation

Auxin (IAA)

retards leaf abscission

Cytokinins

These are synthesized primarily in roots and transported to other organs, although there are many minor sites of production as well

Cytokinins

Regulates cell division in shoots and roots

Cytokinins

modify apical dominance and promote lateral bud growth

Cytokinins

promote movement of nutrients into sink tissues

Cytokinins

stimulate seed germination

Cytokinins

delay leaf senescence

Gibberellins

Meristems of apical buds and roots, young leaves and developing seeds are the primary sites of production

Gibberellins

Stimulates stem elongation, pollen development, pollen tube growth, fruit growth, and seed development and germination

Gibberellins

regulate sex determination and the transition from juvenile to adult phases

Brassinosteroids

These compounds are present in all plant tissues although different intermediates predominant in different organs

Brassinosteroids

Internally produced brassinosteroids act near the site of synthesis

Brassinosteroids

Promote cell expansion and cell division in shoots

Brassinosteroids

promote root growth at low concentrations

Brassinosteroids

inhibit root growth at high concentrations

Brassinosteroids

promote xylem differentiation and inhibit phloem differentiation

Brassinosteroids

promote seed germination and pollen tube elongation

Abscisic acid (ABA)

Almost all plant cells have the ability to synthesize abscisic acid, and its presence has been detected in every major organ and living tissue

Abscisic acid (ABA)

may be transported in the phloem or xylem

Abscisic acid (ABA)

Inhibits growth

Abscisic acid (ABA)

promotes stomatal closure during drought stress

Abscisic acid (ABA)

promotes seed dormancy and inhibits early germination

Abscisic acid (ABA)

promotes leaf senescence

Abscisic acid (ABA)

promotes desiccation tolerance

Strigolactones

These carotenoid-derived hormones and extracellular signals are produced in roots in in response to low phosphate conditions or high auxin flow from the shoot

Strigolactones

Promote seed germination control of apical dominance and the attraction of mycorrhizal fungi to the root

Ethylene

This gaseous hormone can be produced by most parts of the plant

Ethylene

It is produced in high concentrations during senescenceleaf abscission, and the ripening of some types of fruit

Ethylene

Synthesis is also stimulated by wounding and stress

Ethylene

Promotes ripening of many types of fruit, leaf abscission and the triple response in seedlings (inhibition of stem elongation promotion of lateral expansion and horizontal growth)

Ethylene

enhances the rate of senescence

Ethylene

promotes root and root hair formation

Ethylene

promotes flowering in the pineapple family

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