ABA effects on ethylene production, PAL activity, anthocyanin and phenolic contents of strawberry fruit

Effects of exogenously applied abscisic acid (ABA) on ethylene production rate, phenylalanine ammonia-lyase ( PAL) enzyme activity, and anthocyanin and phenolic concentrations in harvested strawberry cv. Everest fruit were evaluated. Colouration and firmness were also assessed on fruit held for 3 days at 20 degreesC. ABA treatment accelerated fruit colour and softening. Treatment with 10(-5) or 10(-4) mol ABA l(-1) stimulated ethylene production. Anthocyanin and phenolic contents and PAL activity increased during storage, but more rapidly in ABA treated fruit. As a result, red colour development was accelerated. Endogenous ABA may play a role in strawberry fruit colour development during ripening through up-regulation of ethylene production and PAL activity.