Brassinosteroids bioassay

Bioassay Studies of Brassins - BARC As indicated by Mandava (3), bioassay systems have been rather extensively used to study brassins physiology. In addition to the bean 2nd internode bioassay, the bean first internode curvature bioassay (28) and the mung bean epicotyl bioassay (29) were found to be useful by Meudt and Gregory. In many cases, details of early brassins studies using these and other assay systems were not published because the chemical nature of the active component(s) of brassins was unknown at the time. However, types of responses obtained with the synthetic brassinosteroids were essentially the same as those obtained with brassins (29, 30, 31, 32, 33). ... 

J.H. Yopp, Southern Illinois University, Carbondale, became interested in the brassins project in its early stages (36) and he conducted cooperative brassins studies with both Mitchell and Mandava. Yopp et al. (37, 38) evaluated brassins responses in a number of auxin, gibberellin, and cytokinin bioassays and showed that brassins responded similarly to some of the known hormones in certain systems but not in others. These studies led to more cooperative investigation of brassinolide and other brassinosteroids (39, 40). 

Interest in the brassinosteroids grew as a result of these bioassay studies and much cooperative work has been conducted with scientists in various parts of the world using brassinosteroid samples synthesized by M. J. Thompson, USDA, (ret.) (3,31). 

The Rice Lamina Inclination as a Specific Bioassay for Brassinosteroids... 

The beginning of brassinosteroid research in Japan was initiated with Distylium factor research. Distylium factors were discovered in Distylium racemosum leaves, when bioassayed, using... 

Some structure-activity relationships, synthesis of new brassinosteroids, and new sensitive bioassays for brassinosteroids are presented. 

Different Activities of Several Brassinosteroids in Two Bean Internode Tests. It is a well-known phenomenon that structurally closely related plant growth regulators exhibit different orders of activity in different bioassays. This makes it difficult to define the criteria of specificity of their hormonal action. The same situation exists in the case of BRst, and it can be documented by the comparison of different BRst in the two bioassays. 

Examination on the production of brassinosteroid-like active substances. The cells were extracted with methanol, and the NE fractions of the extracts were subjected to bioassay using the rice lamina inclination test by the same... 

There are many naturally occurring compounds that have plant growth regulatory effects in whole plants or bioassays, and brassinosteroids are certainly potent - but should they have plant hormone status ... 

We are able to readily search for naturally occurring brassinosteroid using rice-lamina joint test [LJT] (1) as the bioassay method and GC/MS as the microanalytical method, which was established by Ikekawa and his co-workers as a microanalytical method for BS (2). Plant material was extracted three times in methanol or 80% methanol-H20. After the extract was evaporated under reduced pressure, the resulting aqueous residue was extracted with EtOAc at pH3 and the EtOAc fraction was partitioned with Na2C03-NaHC03 buffer at pH 10 to get neutral substances. 

We conclude that brassinosteroids may have a slight (if any) agonistic activity in a bioassay for ecdysteroids More importantly, they reveal a significant antagonistic activity. This antagonistic effect is dose dependent and reversible. 

We developed several methods for construction of the side chain and the A/B ring of brassinosteroids, and synthesized more than fifty analogs (6). In order to obtain the structure-activity relationship, those analogs were subjected to bioassay in the rice-lamina inclination (7), Raphanus, and tomato tests (5). In general, die structural... 

Recently, by the ligand-accelerated osmium catalyzed asymmetric hydroxylation using a cinchona alkaloid derivative, the 22/ ,23/ -epimer was obtained as the major product of the oxidation (77). Thus, epibrassinolide may be ideal for practical use, and, therefore, is one of the most desirable brassinosteroids because of the ease with which it can be synthesized. This compound showed about one tenth the activity of brassinolide in Raphanus and tomato bioassay (5). In field trials, the activity of epibrassinolide was about the same as of brassinolide. Epibrassinolide is a natural sterol. This was confirmed by GC-MS analysis, which identified epibrassinolide, along with co-existing brassinolide, brassinone, and castasterone, from the bee pollen of the broad bean Vida faba obtained in China (72). 

Brassinolide is known as the most potent compound for inducing plant growth promoting activity in various bioassay systems. Many researchers have attempted to demonstrate brassinosteroid application for agricultural use. However, test results have been disappointing in many cases under field conditions. Here, we discuss the capability and problems surrounding the potential practical uses of brassinosteroids. 

Barley field experiments, description for brassin evaluation, 12 Barley leaf cell ultrastructure, protective effect of brassinosteroids under saline stress, 150,152/153,154/ Bean first-intemode bioassay, 321 Bean second-intemode bioassay activities of compounds, 65,68,69-7Of application, 321 brassin purification, 3-4 brassinosteroids, description, 109-110 development, 321 scheme, 63,65,66/... 

It is suggested that the biological activity of some of these brassinosteroids might be due to their conversion to brassinolide by the plant tissue during the bioassay (15). This will require further investigation. 

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