Stimulation of Orobanche ramosa seed germination by fusicoccin derivatives: A structure-activity relationship study

Abstract

A structure-activity relationship study was conducted assaying 25 natural analogs and derivs. of fusicoccin (FC), and cotylenol, the aglycon of cotylenins, for their ability to stimulate the seed germination of the parasitic species Orobanche ramosa. Some of the compds. tested proved to be highly active, being 8,9-isopropylidene of the corresponding FC aglycon and the dideacetyl deriv. the most active FC derivs. In both groups of glucosides and aglycons (including cotylenol), the most important structural feature to impart activity appears to be the presence of the primary hydroxy group at C-19. Furthermore, the functionalities and the conformation of the carbotricyclic ring proved to play a significant role. The dideacetyl deriv. of FC, being easily and rapidly obtainable in high yield starting by FC, could be of interest for its practical application as a stimulant of Orobanche ramosa seed germination, inducing the "suicidal germination", an interesting approach for parasitic plant management