Brassinolide 0.2%SP Plant Growth Hormone

                                                                            Brassinolide

Brassinolide is a plant hormone. The first isolated brassinosteroid,

it was discovered when it was shown that pollen from rapeseed (Brassica napus) could promote stem elongation and cell division.

The biologically active component was isolated and named brassinolide.

Brassinosteroids (BRs) are now recognized as a major hormone controlling plant growth and development  

Up to now more than 40 BRs have been fully characterized.

The biosynthetic pathways of brassinolide (BL), the most active BR, have been elucidated using cultured cells of Catharanthus roseus.

Through extensive metabolic studies, parallel branched pathways for BL, namely the early C6-oxidation and late C6-oxidation pathways,

have been proposed. The first reaction toward BL is the conversion of campesterol (CR) to campestanol (CN), and then CN is converted to

castasterone (CS) through either the early C6-oxidation pathway or the late C6-oxidation pathway.

Finally CS is converted to BL, the most active BR. The natural occurrence of most BR intermediates was demonstrated in cultured cells of C.

roseus. In addition most of the steps were defined by feeding deuterium-labeled substrates followed by identification of the metabolites using gas

chromatography-mass spectrometry (GC-MS). However, some steps remained to be validated. In fact the first proposed biosynthetic step, namely

the conversion of CR to CN, was only recently refined . The study revealed the biosynthetic scheme CR → (24R)-24-methylcholest-4-en-3β-ol →

(24R)-24-methylcholest-4-en-3-one→(24R)-24-methyl-5α- cholestan-3-one → CN in cultured cells of C. roseus and seedlings of Arabidopsis.

These findings were based on the identification of endogenous intermediates and demonstration of the reaction sequence by the metabolic

studies. More recently the step from 6-oxocampestanol (6-OxoCN) to cathasterone (CT) has been demonstrated in cultured cells of C. roseus .

This result, together with our previous studies completed the documentation of the early C6-oxidation pathway. However, the sequence, CN → 6-

deoxocathasterone (6-DeoxoCT) → 6-deoxoteasterone (6-DeoxoTE) in the late C6-oxidation pathway has remained hypothetical.