Abstract
Gray mold (Botrytis cinerea Persoon) induced the accumulation of scoparone (6,7-dimethoxycoumarin) in the flavedo of fruit in all citrus species used in this study. The time-course of the accumulation of this compound was species dependent. In the fruit of ‘Kiyomi’ and Meiwa kumquat, scoparone accumulated gradually over several days after inoculation. No accumulation occurred in the non-inoculated citrus fruit. In several citrus species, including Tankan, ‘Seminole’, and ‘Ellendale’, Scoparone concentration increased up to 4 days after treatment. In ‘Murcott’, ‘Triumph’, and Yuzu, the maximum concentration was observed within 7 days of treatment. On the other hand, in ‘Imamura-unshu’, ‘Kawano Natsudaidai’, Ponkan, ‘Morita Navel’, Kinukawa, ‘Eureka’ lemon, kumquats, calamondin, and citrangequat, the increase in scoparone was much lower. These results suggest that scoparone is a phytoalexin induced by gray mold, accumulating in a broad range of citrus species.
