A typical example of plant growth regulator is a plant hormone. Plant hormones are the collective term for compounds produced in minute amounts by plants to regulate their own physiological functions. To date, seven natural plant hormones have been discovered: auxins, cytokinins, ethylene, jasmonates, abscisic acid, gibberillins and brassinosteroids (Fig. 1). Unnatural plant growth regulators or plant growth inhibitors are also included in this section.

Auxins

Cytokinins

Jasmonates

Abscisic Acid

Miscellaneous Plant Growth Regulators

Auxins

Historically, auxins were first discovered as substances which showed phototropism. To date, it has been revealed that they play numerous roles such as initial development, budding, root growth development, growth of flower parts and cell division. Natural auxins are 3-indoleacetic acid, 3-indolebutyric acid and phenylacetic acid. Some unnatural synthetic compounds also exhibit the same activities.

N0005	T0451	D0396
N0624	C0940	N0045
I0022	I0026	I0032
B2746	C0250	N0006
I0023	N0007	D1319

N0005	1-Naphthaleneacetic Acid
T0451	2,3,5-Triiodobenzoic Acid
D0396	2,4-Dichlorophenoxyacetic Acid
N0624	2-(1-Naphthyl)acetamide
C0940	2-(4-Chlorophenoxy)isobutyric Acid
N0045	2-Naphthyloxyacetic Acid
I0022	3-Indoleacetic Acid
I0026	3-Indolebutyric Acid
I0032	3-Indolepropionic Acid
B2746	4-Bromophenoxyacetic Acid
C0250	4-Chlorophenoxyacetic Acid
N0006	Potassium 1-Naphthaleneacetate
I0023	Potassium 3-Indoleacetate
N0007	Sodium 1-Naphthaleneacetate
D1319	Sodium 2,4-Dichlorophenoxyacetate Monohydrate

Cytokinins

Cytokinins are regarded as substances which stimulate cell division, shoot initiation and bud formation, when addition auxins are added. Typical structure features are adenine with an isopentenyl unit at N⁶ position, or with an isopentenyl unit with the methyl terminus being hydroxylated.

C0031	C0926	A0149
A0151	K0009	B1088
Z0012

C0031	1,3-Diphenylurea
C0926	1-(2-Chloro-4-pyridyl)-3-phenylurea
A0149	Adenine
A0151	Adenine Sulfate Dihydrate
K0009	Kinetin
B1088	N6-Benzyladenine
Z0012	trans-Zeatin

Jasmonates

Jasmomates have a distinct fragrance and are biosynthesized from linolenic acid, an unsaturated fatty acid. They inhibit growth in adverse conditions, and stimulate tuber formation. They promote senescence of leaves, suppression of fruit growth, and the induction of tuber formation in potatoes.

D3225	J0004	D1431
M1068

D3225	(+/-)-Dihydrojasmonic Acid
J0004	(+/-)-Jasmonic Acid
D1431	Methyl Dihydrojasmonate (cis- and trans- mixture)
M1068	Methyl Jasmonate

Abscisic Acid

Abscidic acid is occasionally classified as a sesquiterpene, however, it is biosynthesized from a carotenoid (C₄₀) precursor. It stimulates the closure of stomata in the absence of water and induces seeds to synthesize storage proteins. It is also released when a plant experiences stress, as in lack of nutrition, pests, root distress, or disease.

A1698

A0792

A1698	(S)-(+)-Abscisic Acid
A0792	Abscisic Acid (synthetic)

Miscellaneous Plant Growth Regulators

D2191	T1049	T1809
A0325	B2829	C0172
C0380	G0029	M0015
P0249

D2191	(-)-2,3:4,6-Di-O-isopropylidene-2-keto-L-gulonic Acid Monohydrate
T1049	1-Triacontanol
T1809	3-(Trifluoroacetyl)indole
A0325	5-Aminolevulinic Acid Hydrochloride
B2829	Brassinazole
C0172	Chlorocholine Chloride
C0380	Colchicine (contains 5% Ethyl Acetate at maximum)
G0029	Gibberellin A3
M0015	Maleic Hydrazide
P0249	Phloroglucinol Anhydrous