Abscisin II and , some. Hormone-Regulated Plant Responses

Abstract

The aotivity of (�)-absoisin II' [(�)AbII] and its interaction with a number of plant growth regulators in the oontrol of lettuce germination, lettuoe hypoootyl and radiole elongation, ououmber seedling growth, radish lea ( senesoenoe, and barley vernalization were examined. The interac.tions between (� )AbII and th�;l promoting h~rmones were of two general types. In gibberellio acid (GAs)-promoted lettuoe germination and kinetin-oontrolled leaf senesoenoe, the effeots of low ooncentrations of ( � )-!\bII were oompletely overoome by high oonoentratioileof the other substanoe. In .the second type of interaction, (� )AbII was inhibitory only in the presenoe of high oonoentrations of the promoter (kinetin in lettuce germinatipn and allogibberio acid in lettuoe radicle elongation). Cuoumber radiole elongation, on the other hand, was promoted by (� )AbII in the presenoe of a mixture of GA4 and GA7.