INTERTISSUE SIGNALING DURING THE 2-PHASE ABSCISSION IN OIL PALM FRUIT

Shedding of oil palm fruit from the spike takes place in two stages. T he first, cell separation at the junction of the fruit base and the pe dicel (position 1) is initiated by ethylene or its precursor (ACC) or by treatments that accelerate the production,of ethylene (ABA). Separa tion is delayed or suppressed by treatments that block ethylene biosyn thesis (AOA) or oppose ethylene action (auxin, 2,4-D). Separation of c ells at the fruit base from the rudimentary androecium or from the rin g of tepals at the pedicel edge is a second stage event that depends u pon the achievement of separation at position 1. Abscission cells diff erentiated at these secondary positions do not separate in response to ethylene or to ethylene enhancing compounds alone. It is concluded th at a chemical stimulus from the separated position 1 provides the sign al that induces the second cell separation process essential to the co mpletion of fruit shedding.