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

Shedding of oil palm fruit from the spike takes place in two stages. The first, cell separation at the junction of the fruit base and the pedicel (position 1) is initiated by ethylene or its precursor (ACC) or by treatments that accelerate the production,of ethylene (ABA). Separation is delayed or suppressed by treatments that block ethylene biosynthesis (AOA) or oppose ethylene action (auxin, 2,4-D). Separation of cells at the fruit base from the rudimentary androecium or from the ring of tepals at the pedicel edge is a second stage event that depends upon the achievement of separation at position 1. Abscission cells differentiated at these secondary positions do not separate in response to ethylene or to ethylene enhancing compounds alone. It is concluded that a chemical stimulus from the separated position 1 provides the signal that induces the second cell separation process essential to the completion of fruit shedding.