title: Defensive role of tomato polyphenol oxidases against cotton bollworm (Helicoverpa armigera) and beet armyworm (Spodoptera exigua).
abstract: Tomato (Solanum lycopersicum) polyphenol oxidases (PPOs), enzymes that oxidize phenolics to quinones, have been implicated in plant resistance to insects. The role of PPO in resistance to cotton bollworm [Helicoverpa armigera (Hübner)] and beet armyworm [Spodoptera exigua (Hübner)] (Lepidoptera: Noctuidae) was evaluated. Consumption, weight gains, and mortality of larvae feeding on foliage of transgenic tomato lines overexpressing PPO (OP lines) and of larvae feeding on foliage of transgenic tomato lines with suppressed PPO (SP lines) were compared with consumption, weight gains, and mortality of larvae feeding on non-transformed (NT) plants. Increases in foliage consumption and weight gains were observed for cotton bollworms feeding on leaves of SP plants compared to NT and OP plants. PPO activity was negatively correlated with both weight gains and foliar consumption of cotton bollworm, substantiating the defensive role of PPO against this insect. Similarly, beet armyworm consumed less foliage (both young and old leaves) from OP plants than SP plants. Larvae feeding on OP leaves generally exhibited lower weight gains than those feeding on SP leaves. These results indicate that tomato PPO plays a role in resistance to both cotton bollworm and beet armyworm.
authors.affiliation: Institute of Agricultural Technology, Suranaree University of Technology, Muang District, Nakhon Ratchasima, Thailand.
authors.forename: Anongnut
authors.initials: A
authors.lastname: Bhonwong
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Stout
authors.forename: Jutharat
authors.initials: J
authors.lastname: Attajarusit
authors.forename: Piyada
authors.initials: P
authors.lastname: Tantasawat
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000502:physiology; D007915:Lepidoptera / Q000502:physiology*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000469:parasitology*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000469:parasitology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified
chemical_list: D010940:Plant Proteins; D004156:Catechol Oxidase