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.

B2746	C0250	C0940
D0396	D1942	E0878
I0022	I0024	I0026
I0032	N0005	N0624
N0045	I0023	N0006
D1319	N0007	T0451

B2746	4-Bromophenoxyacetic Acid
C0250	4-Chlorophenoxyacetic Acid
C0940	2-(4-Chlorophenoxy)isobutyric Acid
D0396	2,4-Dichlorophenoxyacetic Acid
D1942	2-(2,4-Dichlorophenoxy)propionic Acid
E0878	Ethyl 3-Indoleacetate
I0022	3-Indoleacetic Acid
I0024	3-Indoleacetonitrile
I0026	3-Indolebutyric Acid
I0032	3-Indolepropionic Acid
N0005	1-Naphthaleneacetic Acid
N0624	2-(1-Naphthyl)acetamide
N0045	2-Naphthyloxyacetic Acid
I0023	Potassium 3-Indoleacetate
N0006	Potassium 1-Naphthaleneacetate
D1319	Sodium 2,4-Dichlorophenoxyacetate Monohydrate
N0007	Sodium 1-Naphthaleneacetate
T0451	2,3,5-Triiodobenzoic Acid

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.

A0149	A0151	B1088
C0926	C0031	K0009
Z0012

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

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.

A0792

A1698

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

Miscellaneous Plant Growth Regulators

A0325	B2829	C0172
C0380	D2191	D4016
G0029	M0015	P0249
T1049	T1809

A0325	5-Aminolevulinic Acid Hydrochloride
B2829	Brassinazole
C0172	Chlorocholine Chloride
C0380	Colchicine (contains 5% Ethyl Acetate at maximum)
D2191	(-)-2,3:4,6-Di-O-isopropylidene-2-keto-L-gulonic Acid Monohydrate
D4016	1,1-Dimethylpiperidinium Chloride
G0029	Gibberellin A3
M0015	Maleic Hydrazide
P0249	Phloroglucinol Anhydrous
T1049	1-Triacontanol
T1809	3-(Trifluoroacetyl)indole