Phytoalexin scoparone (6,7-dimethoxycoumarin) generally was not detected in noninoculated lemon fruit (Citrus limon [L.] Burm., cv Eureka) but accumulated in fruit after inoculation with Penicillium digitatum Sacc. A much greater increase in the amount of scoparone was found in fruit exhibiting an incompatible response to Penicillium after heat treatment at 360C for 3 days. Heat treatment prevented development of decay in the inoculated fruit. The concentration of the compound after inoculation continued to increase during and after the heat treatment period, reaching 178 micrograms per gram fresh weight of the flavedo 6 days after the heat treatment. Changes in scoparone concentration in fruit were closely correlated with the changes in the antifungal activity of the fruit extract. A low concentration of the phytoalexin was detected in fruit injured mechanically. Scoparone also accumulated in the fruit following ultraviolet illumination; the concentration of the compound was dose-dependent. Median effective dose values of the inhibition of germ tube elongation and spore germination of P. digitatum were 29 and 46 micrograms per milliliter, respectively. Our findings suggest that the rapid increase in scoparone concentration plays an important role in the increased resistance of heat-treated lemon fruit to infection by P. digitatum.

The polyatomic tetrahydroxytetraindium(III) cations, In 4 (OH) 4 8+ , have been synthesized in 94% of the sodalite cavities of zeolite Y (FAU, Si/Al ) 1.69). In-Y (|In 57.8 [In 5 ] 1.8 |[Si 121 Al 71 O 384 ]-FAU or In 66.8 -Y) was prepared by the oxidative solid state ion exchange (OSSIE) method from In 0 and single crystals of Tl-Y under anhydrous conditions at 623 K. One of these was exposed to the atmosphere and then zeolitically dry oxygen, both at 623 K, to give In-Y[In 4 (OH) 4 ] (|In 7.6 [In 4 (OH) 4 ] 7.5 [In(OH) 2 ] 2.0 |[Si 121 Al 71 O 384 ]-FAU or In 39.6 (OH) 34.0 -Y). The structures of In-Y and In-Y[In 4 (OH) 4 ] were determined by single crystal crystallography with synchrotron X-radiation. They were refined in the space group Fd3m j (a ) 24.863(1) and 24.518(1) Å) with all unique data to the final error indices R 1 ) 0.050 and 0.057 for the 1110 and 1037 reflections for which F o > 4σ(F o ), respectively. The In in In-Y is mostly In + ; some In 5 7+ clusters are present in sodalite cavities. Upon oxidation in the presence of water, 41% of the In exited the zeolite. Most of the remainder formed In 4 (OH) 4 8+ clusters in the sodalite cavities of In-Y[In 4 (OH) 4 ]. In 4 (OH) 4 8+ is a tetrahedrally distorted In 4 O 4 cube with a hydrogen atom bound to each oxygen atom. In In 4 (OH) 4 8+, each In 3+ ion lies opposite a double 6-ring and is 6-coordinate octahedral with three bonds to OHanions (2.245(4) Å) and three to framework oxygens (2.198(5) Å); each OHion is near a single 6-ring to which it hydrogen bonds. Small amounts of In(OH) 2 + , In 2+ , and In + were also found.

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Ultraviolet (UV) illumination (254 nm) induced production of the phytoalexin scoparone in flavedo of kumquat (Fortunella margarita Lour. Swingle cv. Nagami) and orange [Citrus sinensis (L.) Osbeck cvs. Shamouti and Valencia]. Trace amounts of scoparone (<2.0 μg·g-1 fresh weight of flavedo) were detected in nontreated fruits. Phytoalexin accumulation in kumquat reached a peak of 530 μg·g-1 11 days after illumination, hut the amount declined rapidly, returning to a trace level 1 month after treatment.. Production of scoparone in illuminated fruits was enhanced by increasing the UV dose from 1.5 × 103 to 9.0 × 103 J·m-2 for orange and from 0.2 × 103 to 1.5 × 103 J·m-2 for kumquat and by raising the storage temperature from 2 to 17C. Phytoalexin accumulation correlated with an increase in antifungal activity of flavedo extracts. UV-illuminated kumquat fruit inoculated with Penicillium digitatum Sacc. 2 days after treatment had a lower incidence of decay than the control. Illumination of previously inoculated fruit failed to prevent decay. Kumquat fruit stored at 17C showed signs of UV-induced peel damage. Chemical name used: 6,7-dimethoxycoumarin (scoparone).

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