POTAMOGETON PECTINATUS IS CONSTITUTIVELY INCAPABLE OF SYNTHESIZING ETHYLENE AND LACKS 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID OXIDASE

A highly sensitive laser-driven photoacoustic detector responsive to l ess than or equal to 2.1 nmol m(-3) ethylene (50 parts per trillion [v /v]) was used for ethylene analysis. Dark-grown plants of Potamogeton pectinatus L. growing from small tubers made no ethylene. Exposure of shoots to white light, wounding, submergence in water followed by desu bmergence, partial oxygen shortage, indole acetic acid, or carbon diox ide failed to induce ethylene production, although clear effects were observed in Pisum sativum L. Some ethylene was released after applying high concentrations of the ethylene precursor 1-aminocyclopropane-1-c arboxylic acid (ACC; 10 mol m(-3)) to P. pectinatus, but the amount wa s trivial compared with that released by P. sativum. More endogenous A CC was found in P. pectinatus than in P. sativum. Considerable ACC oxi dase activity was present in tissue extracts of P. sativum. However, n o ACC oxidase activity was found in P. pectinatus, indicating that thi s is where ethylene production is arrested.