ETHYLENE BIOSYNTHESIS AND RESPIRATION IN STRAWBERRY FRUIT TREATED WITH DIAZOCYCLOPENTADIENE AND IAA

Diazocyclopentadiene (DACP), an inhibitor of ethylene action, was used to investigate the role of ethylene receptor(s) in regulating ethylen e biosynthesis and respiration in strawberry fruit. DACP stimulated et hylene production of fruit at all stages of maturity. This stimulation was mainly due to an increase in ACC content in the tissue without si gnificantly changing ACC oxidase activity. DACP did not induce any cha nge in respiration in fruit at various stages of maturity except the e arly green stage (green I). We also investigated the possible interact ion of DACP and IAA in ethylene production. Results indicated that all treatments increased ethylene production compared to the control alth ough the absolute ethylene production differed in the order IAA plus D ACP > only DACP > only IAA > control. IAA stimulated ethylene producti on without change of ACC oxidase activity at 1 day after treatment in strawberry fruit at pink stage. Results suggest that ethylene biosynth esis in nonclimacteric strawberry fruit at various stages of maturity may be regulated by ethylene receptor(s) with inhibition of ethylene p roduction. DACP may release this inhibitory effect, and resulting in i ncreasing ethylene production. Results also indicated that respiration may not be regulated by an ethylene receptor in strawberry fruit at m ost stages of maturity. DACP and IAA showed interaction in regulation of ethylene production which was caused by an increase in ACC content, not ACC oxidase activity.