The green fluorescence (530 nm) of 7-azaindole tautomer is shown to be observable at room temperature upon microaddition of water (0.008 M to saturation) to ethyl ether and to p-dioxane (0.17-1.7 M) as solvent. The fluorescence of 7-azaindole observed in liquid water solution (Ama -385 nm) is thus shown to correspond to the normal molecule (fluorescence at -350 nm in ether), contrary to current proposals suggesting that this latter fluorescence corresponds to the tautomer. The present experiments indicate that 7-azaindole monohydrate undergoes excited-state double-proton transfer. The results also suggest that 7-azaindole polyhydrate, which is expected to be prevalent in water solvent, inhibits the solvent rearrangement that is necessary for tautomerization, resulting in a diminished tautomer fluorescence intensity. IntroductionThe spectroscopy and dynamics of 7-azaindole (7AI) have received considerable attention since the initial observation of excited-state double-proton transfer (ESDPT) by Taylor et al.'

Jasmonates, such as jasmonic acid (JA), are plant-signaling compounds that trigger induced resistance against certain pathogens and a broad range of arthropod herbivores. One goal of this study was to determine the effects of JA-dependent defenses in tomato on root-knot nematodes. Another was to determine if the artificial induction of these defenses could enhance nematode control on plants that carry Mi-1.2, a nematode resistance gene that is present in many tomato cultivars. At moderate soil temperatures, Mi-1.2 can effectively suppress reproduction of most isolates of the common root-knot nematode species Meloidogyne javanica, M. incognita, and M. arenaria. Mi-mediated resistance has its limitations, however. Mi-1.2 is reported to lose its effectiveness at soil temperatures above 28 degrees C, and certain virulent nematode isolates can overcome resistance even at moderate soil temperatures. This study used a foliar application of JA to activate induced resistance in two near-isogenic lines of tomato (Lycopersicon esculentum) with and without Mi-1.2, and evaluated the effects of induced resistance at moderate soil temperatures on one avirulent nematode isolate (M. javanica isolate VW4) and two virulent isolates (M. javanica isolate VW5 and M. incognita isolate 557R). In addition, the effects of induced resistance on avirulent nematode performance were examined at a high temperature (32 degrees C). The results indicate that JA application induces a systemic defense response that reduces avirulent nematode reproduction on susceptible tomato plants. Furthermore, JA-dependent defenses proved to be heat-stable, whereas the effects of Mi-mediated resistance were reduced but not eliminated at 32 degrees C. JA treatment enhanced Mi-mediated resistance at high temperature, but did not suppress either of the virulent nematode isolates tested.

No abstract

We examined the effects of three forms of host plant resistance in tomato, Lycopersicon esculentum, on the potato aphid, Macrosiphum euphorbiae. Mi-1.2, a resistance gene (R-gene) in tomato that deters aphid feeding, reduced the population growth of both potato aphid isolates tested, although it appeared to have a greater impact on isolate WU11 than on isolate WU12. The results suggest that there may be quantitative differences in virulence between these two aphid isolates. We also examined two distinct forms of acquired resistance in tomato, jasmonic acid (JA)-dependent and salicylic acid (SA)-dependent induced defenses. Exogenous foliar application of JA triggered expression of a JA-inducible proteinase inhibitor in tomato cultivars with and without Mi-1.2, although the effects of treatment on aphid performance differed between these cultivars. JA-treatment reduced aphid population growth on a susceptible tomato cultivar that lacks Mi-1.2, but did not significantly enhance or inhibit aphid control on a near-isogenic resistant tomato cultivar that carries this gene. Foliar application of an SA analog, benzothiadiazole (BTH), was used to induce SA-dependent defenses. BTH treatment reduced the population growth of both aphid isolates on a susceptible tomato cultivar, and also enhanced aphid control on a resistant cultivar. The results indicate that both SA- and JA-dependent acquired resistance in tomato have a direct negative effect on a phloem-feeding insect. Furthermore, this study demonstrates that acquired resistance and R-gene-mediated resistance can interact for enhanced suppression of insect herbivores.