XVI International Botanical Congess

Abscission involves the dissolution of cell walls as a consequence of secretion of hydrolytic enzymes at points of detachment. A reverse transcriptase (RT)-PCR strategy using degenerate oligonucleotides has led to the amplification of a single PG that is specifically upregulated in ethylene-treated abscission zone tissue and studies of expression of this gene are being carried out to examine the contribution of this enzyme to abscission. The mRNA encoding this polyglacturonase is up regulated within 24 h of exposure of leaf and flower abscission zone tissue to ethylene, this precedes cell separation by 24 h in leaves. The mRNA can also be detected in petiole tissue after 36 h exposure to ethylene. We have evidence that a signal maybe passing from zone to non-zone tissue that leads to the up regulation of this PG mRNA.