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Resistance

The Involvement of Marmesin in Celery Resistance to Pathogens During Storage and the Effect of Temperature on Its Concentration. U. Afek, Department of Postharvest Science and Fresh Produce, ARO, The Volcani Center, Bet Dagan 50250, Israel; N. Aharoni(2), and S. Carmeli(3). (2)Department of Postharvest Science and Fresh Produce, ARO, The Volcani Center, Bet Dagan 50250, Israel; (3)School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. Phytopathology 85:1033-1036. Accepted for publication 9 January 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-1033.

We show evidences that (+)marmesin, rather than linear furanocoumarins (psoralens), may play the major role in celery resistance to pathogens during storage. (+)Marmesin, the precursor of psoralens in celery, has at least 100 times greater antifungal activity in vitro in the dark than psoralens. Increased susceptibility of celery to pathogens during 1 mo of storage was accompanied by a decrease in (+)marmesin concentration and a corresponding increase in psoralen concentration. An increase in celery decay was negatively correlated with (+)marmesin concentration and positively correlated with psoralen concentration. After 1 mo of storage at 0 or 2 C, the concentration of psoralens increased from 10 to 136 or 78 g g1 fr. wt., respectively, while the concentration of (+)marmesin under the same storage conditions decreased from 33 to 4 or 11 g g1 fr. wt., respectively. Incidence of decay after 1 mo of storage at 0 or 2 C was 62 or 27%, respectively.

Additional keywords: phytoalexins.