Effects of absicisc acid and abscisic acid analogs on the induction of freezing tolerance of winter rye (Secale cereale L.) seedlings

摘要

Rye cv. Puma plants grown at 25/15deg C (dayight) were treated with abscisic acid (ABA) or 1 of 16 analogues as a foliar spray or a root drench on 2 consecutive days, and freezing tolerance was determined 1, 2 and 4 days after the second treatment. All analogues were more effective when applied to the plant roots than when applied to the leaves. ABA, acetylenic ABA and 2',3'- dihydroacetylenic ABA increased freezing tolerance from -3deg C (control) to -9deg C. Consistent structure/activity relationships were only detected following root application. No single functional group alteration was essential for activity. The effect of any given change to the molecule was modified by the presence of other functional groups. For example, substituting the double bond in the ring with a single bond decreased activity, but concomitant substitution of the trans double bond in the side chain with a triple bond restored activity. In general, analogues with a cis, trans side chain were more active initially but rapidlylost activity, whereas acetylenic analogues maintained or gained activity over the three sampling dates. The application of gibberellin biosynthesis inhibitors (tetcyclacis or mefluidide) did not increase freezing tolerance beyond that induced by ABA, either alone or in combination with ABA.