Western flower thrips (WFT), Frankliniella occidentalis, is a serious insect pest of Chrysanthemum [Chrysanthemum × morifolium Ramat. (Asteraceae)]. Here we have investigated whether genotypic variation in constitutive and inducible resistance to WFT correlates with phenotypic differences in leaf trichome density and the activity of the defense-related enzyme polyphenol oxidase (PPO) in chrysanthemum. Non-glandular and glandular leaf trichome densities significantly varied among ninety-five chrysanthemum cultivars. Additional analyses in a subset of these cultivars, differing in leaf trichome density, revealed significant variation in PPO activities and resistance to WFT as well. Constitutive levels of trichome densities and PPO activity, however, did not correlate with chrysanthemum resistance to WFT. Further tests showed that exogenous application of the phytohormone jasmonic acid (JA) increased non-glandular trichome densities, PPO activity and chrysanthemum resistance to WFT, and that these effects were cultivar dependent. In addition, no tradeoff between constitutive and inducible resistance to WFT was observed. JA-mediated induction of WFT resistance, however, did not correlate with changes in leaf trichome densities nor PPO activity levels. Taken together, our results suggest that chrysanthemum can display both high levels of constitutive and inducible resistance to WFT, and that leaf trichome density and PPO activity may not play a relevant role in chrysanthemum defenses against WFT.

西方花蓟马（Frankliniella occidentalis）是一种严重的菊花害虫[菊花× Morifolium拉玛特 （菊科）。在这里，我们研究了对WFT的本构性和诱导抗性的基因型变异是否与叶片毛状体密度的表型差异以及菊花中防御相关酶多酚氧化酶（PPO）的活性有关。在95个菊花品种中，非腺毛和腺毛的毛状体密度显着不同。在这些品种的一个子集中，叶毛密度不同的其他分析表明，PPO活性和对WFT的抗性也存在显着差异。毛状体密度和PPO活性的本构水平与菊花对WFT的抗性无关。进一步的测试表明，外源施用植物激素茉莉酸（JA）可以增加非腺毛的毛密度，PPO活性和菊花对WFT的抗性，并且这些作用与品种有关。另外，未观察到对WFT的本构抗性和诱导抗性之间的权衡。JA介导的WFT抗性诱导与叶片毛状体密度或PPO活性水平的变化均不相关。两者合计，我们的结果表明，菊花可以表现出高水平的对WFT的本构和诱导抗性，并且叶片毛状体密度和PPO活性可能在菊花对WFT的防御中不发挥相关作用。