A Comparison of the Effects of FATTY ACID DESATURASE 7 and HYDROPEROXIDE LYASE on Plant-Aphid Interactions
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
Authors: Li, Jiamei; Avila, Carlos A.; Tieman, Denise M.; Klee, Harry J.; Goggin, Fiona L.
Abstract
The spr2 mutation in tomato (Solanum lycopersicum), which disrupts function of FATTY ACID DESATURASE 7 (FAD7), confers resistance to the potato aphid (Macrosiphum euphorbiae) and modifies the plant's C6 volatile profiles. To investigate whether C6 volatiles play a role in resistance, HYDROPEROXIDE LYASE (HPL), which encodes a critical enzyme in C6 volatile synthesis, was silenced in wild-type tomato plants and spr2 mutants. Silencing HPL in wild-type tomato increased potato aphid host preference and reproduction on 5-week old plants but had no influence on 3-week old plants. The spr2 mutation, in contrast, conferred strong aphid resistance at both 3 and 5 weeks, and silencing HPL in spr2 did not compromise this aphid resistance. Moreover, a mutation in the FAD7 gene in Arabidopsis thaliana also conferred resistance to the green peach aphid (Myzus persicae) in a genetic background that carries a null mutation in HPL. These results indicate that HPL contributes to certain forms of aphid resistance in tomato, but that the effects of FAD7 on aphids in tomato and Arabidopsis are distinct from and independent of HPL.
Thickness-Dependent Order-to-Order Transitions of Bolaform-like Giant Surfactant in Thin Films
MACROMOLECULES
Authors: Hsu, Chih-Hao; Yue, Kan; Wang, Jing; Dong, Xue-Hui; Xia, Yanfeng; Jiang, Zhang; Thomas, Edwin L.; Cheng, Stephen Z. D.
Abstract
Controlling self-assembled nanostructures in thin films allows the bottom-up fabrication of ordered nanoscale patterns. Here we report the unique thickness-dependent phase behavior in thin films of a bolaform-like giant surfactant, which consists of butyl- and hydroxyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS and DPOSS) cages telechelically located at the chain ends of a polystyrene (PS) chain with 28 repeating monomers on average. In the bulk, BPOSS-PS28-DPOSS forms a double gyroid (DG) phase. Both grazing incidence small-angle X-ray scattering and transmission electron microscopy techniques are combined to elucidate the thin film structures. Interestingly, films with thicknesses thinner than 200 nm exhibit an irreversible phase transition from hexagonal perforated layer (HPL) to compressed hexagonally packed cylinders (c-HEX) at 130 degrees C, while films with thickness larger than 200 nm show an irreversible transition from HPL to DG at 200 C. The thickness controlled transition pathway suggests possibilities to obtain diverse patterns via thin film self-assembly.