ROLE OF ABSCISIC-ACID, ETHYLENE AND POLYAMINES IN FLOODING-PROMOTED SENESCENCE OF TOBACCO-LEAVES

The role of abscisic acid (ABA), ethylene and polyamines in leaf senes cence of tobacco exposed to flooding was investigated. Senescence of t obacco leaves was followed by measuring the decrease of protein. Flood ing significantly promoted senescence of tobacco leaves and resulted i n a higher ABA content than the controls throughout the entire 4-day e xperimental duration. Ethylene production in flooding-treated leaves w as much higher than that in control leaves during the first day of the experiment. Putrescine and spermidine, but not spermine, were present in tobacco leaves throughout the experimental duration. Flooded leave s had higher levels of putrescine and spermidine than untreated leaves . It is concluded that ethylene, but neither ABA nor polyamines, is po ssibly involved in the regulation of flooding-promoted senescence of t obacco leaves.