Identification of Ethylene as a Volatile Product of the Fungus Penicillium Digitatum.

Experiments reported independently by BIALE (1) and MILLER, WINSTON, and FISHER (8) revealed that the common green mold of citrus fruits, P. digitatum, produces a physiologically active emanation whose effects on plant tissue are the same as those caused by ethylene gas. It was shown by the latter authors and by BIALE and SHEPHERD (3) that this fungus produces this emanation whether grown on its natural host or in culture, and PRATT (10) showed that production of the emanation does not depend on major nutrient components of the culture solution but does appear to be related to active growth and respiration of the culture. Production of the active gas by fungus-infected fruit has been further studied by ROHRBAUGH (12) and BIALE (2). Except for recent evidence of NICKERSON (9) that ethylene may be produced by Blastomyces dermatitidis and two other human pathogens, P. digitatum is the only fungus reported to have this activity. Biological testing of various other plant pathogens has given negative results (1, 14). Since P. digitatum is a particularly promising organism for the study of the mechanism of ethylene formation, it was of interest to verify chemllically the identity of the active gas produced.