Concentrations Of Brassinolide Research Articles

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

Effect of ABA, GA3, zeatin (Zea) and IAA on the inclination activity was examined by a rice lamina inclination assay using a Korean cultivar, Tongjin. Treatment with ABA, GA3, Zea or IAA alone failed to increase the inclination response significantly at the concentration tested from 0.1 ppm to 10 ppm. However, treatment with 0.1 and 1 ppm ABA in the presence of brassinolide inhibited the inclination activity induced by treatment with brassinolide alone. And treatment with 0.1 and 1 ppm GA3 or Zea in the presence of brassinolide strongly inhibited the inclination activity induced by treatment with brassinolide alone. On the other hand, the inclination activity by treatment with brassinolide alone was clearly promoted by treatment with 0.1 and 1 ppm IAA in the presence of brassinolide. Based on the synergistic effect induced by treatment with BR and IAA, we could develope an improved rice lamina inclination assay whose minimum detectable concentration of brassinolide is 0.00001 ppm /petri dish. The minimum detectable concentration in our assay was five times as low as that of the previous rice lamina inclination assay.

Effect of Brassinolide on Gene Expression in Elongating Soybean Epicotyls

We have studied the effect of brassinolide (BR), a plant steroidal lactone, on the expression of auxin-regulated genes in soybean (Glycine max L. cv Williams 82) epicotyls. BR caused up to 4-fold increases in epicotyl length during extended assays at 10(-7)m, in the absence of added auxin. Structurally related steroids failed to induce elongation or to alter the BR effect. Northern blot analysis, using sequences corresponding to auxin-regulated genes as probes, has shown that the molecular mechanism of BR-induced elongation is likely to differ from that of auxin-induced elongation in this system. BR does not rapidly induce members of the GH, SAUR, or JCW auxin-inducible gene families before the onset of elongation. BR enhances SAUR and GH1 transcripts after 18 h but has no effect on JCW1 or GH3 transcripts at any time examined. We have shown by two-dimensional gel analysis of in vitro translated mRNA that a submicromolar concentration of BR alters the pattern of gene expression in elongating soybean epicotyls.

Effect of brassinolide on the cultured rice root growth as modified by figaron and gibberellic acid.

The excised rice root was cultured by using two separate media. The root base was supplied with 12.5% of sucrose via scutellum, while the root tip was immersed in the inorganic nutrients of MS medium diluted 4 times. Different concentrations of brassinolide were supplied via either root tip (root medium) or root base via scutellum (scutellum medium). Brassinolide supplied to the scutellum medium stimulated the excised root growth at a concentration of 10-8 M, while application of the same concentration to the root medium was found to be drastically inhibitory. Although the single application of either brassinolide (10-8 M) or figaron (10-8 M) to the scutellum medium detectably stimulated root growth, a mixture of them applied to the scutellum medium was shown to be inhibitory for root growth, especially for primary root length while the lateral root length was stimulated. On the other hand when GA3 was supplied to the scutellum medium the primary root length showed a recovery from the slight inhibition observed when brassinolide was applied alone. Results revealed that dispite the observed superiority of the mixture of brassinolide and GA3 in stimulating root growth and the antagonistic effect in the case of brassinolide and figaron, their regulatory effects seemed to be through a different mode of actions.