347 ETHYLENE-INDUCED GENE EXPRESSION DURING FLOWER PETAL ABSCISSION OF ZONAL GERANIUM

Ethylene-regulated gene expression is being studied in several plant systems, but the exact mechanism of ethylene action during plant development and senescence is poorly understood. When geranium (Pelargonium Xhortorum) flowers are exposed to 1 μ1/L of ethylene gas for 1 hour, petals begin to abscise within 60-90 minutes from the start of treatment, The rapidity of the response implies that it must be very direct. We now demonstrate that ethylene acts at the level of message accumulation. We have constructed a cDNA library from mRNA isolated from ethylene-treated geranium gynoecia. Ethylene-induced clones have been isolated by differential screening of this library with cDNA probes synthesized from ethylene-treated and untreated geranium gynoecia mRNA. Identification and characterization of these clones will be discussed.