title: 8[prime]-Methylene Abscisic Acid (An Effective and Persistent Analog of Abscisic Acid).
abstract: We report here the synthesis and biological activity of a new persistent abscisic acid (ABA) analog, 8[prime]-methylene ABA. This ABA analog has one additional carbon atom attached through a double bond to the 8[prime]-carbon of the ABA molecule. (+)-8[prime]-Methylene ABA is more active than the natural hormone (+)-ABA in inhibiting germination of cress seed and excised wheat embryos, in reducing growth of suspension-cultured corn cells, and in reducing transpiration in wheat seedlings. The (+)-8[prime]-methylene analog is slightly weaker than (+)-ABA in increasing expression of ABA-inducible genes in transgenic tobacco, but is equally active in stimulating a transient elevation of the pH of the medium of corn cell cultures. In corn cells, both (+)-ABA and (+)-8[prime]-methylene ABA are oxidized at the 8[prime] position. ABA is oxidized to phaseic acid and (+)-8[prime]-methylene ABA is converted more slowly to two isomeric epoxides. The alteration in the ABA structure causes the analog to be metabolized more slowly than ABA, resulting in longer-lasting and more effective biological activity relative to ABA.
authors.affiliation: Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, Canada S7N 0W9 (S.R.A., P.A.R., A.J.C., J.J.B., B.L.).
authors.forename: S. R.
authors.initials: SR
authors.lastname: Abrams
authors.forename: P. A.
authors.initials: PA
authors.lastname: Rose
authors.forename: A. J.
authors.initials: AJ
authors.lastname: Cutler
authors.forename: J. J.
authors.initials: JJ
authors.lastname: Balsevich
authors.forename: B.
authors.initials: B
authors.lastname: Lei
authors.forename: M. K.
authors.initials: MK
authors.lastname: Walker-Simmons