Effect of grandinol and phloroglucinol derivatives on gibberellin-inducible agr;-amylase synthesis in barley aleurone cells

Grandinol derivatives, which show ABA-like activity in biological tests of seed germination, transpiration and stomatal closure, inhibit gibberellin inducible amylase synthesis. Although these chemicals also inhibit photosynthetic electron transport, the structure activity relationships in inhibiting amylase synthesis was different from that in the inhibition of photosynthetic electron transport. This implies that the action mechanism of these chemicals is different in the two processes. Northern blot analysis showed that the most potent compound, 1,3,5-trihydroxy-4-nitro-2-phenylacetylresorcinol (9), inhibits the expression of agr;-amylase gene, pHv19, as does ABA. These results suggest that compound 9 may act in the same way as ABA or an inhibitor of the signal transduction pathway in barley aleurone cells.