1. Phytolyma lata-induced galling has remained one of the foremost challenges limiting the regeneration of Milicia species in nurseries and degraded forests in West Africa. Although planting of Milicia progenies resistant to Phytolyma attack has been identified as an opportunity for long-term control of the pest, the absence of biomarkers for early detection of resistance has limited the selection of resistant seedlings for planting.
2. We compared phenolic metabolites and oxidative enzymes in resistant and susceptible Milicia progenies with the aim of identifying potential biomarkers for resistance to Phytolyma-induced galling in seedlings.
3. Levels of total phenolics and ortho-dihydroxyphenolics did not significantly differ between the susceptible and resistant saplings or among seedlings. Similarly, peroxidase activity did not differ among sapling progenies or among seedlings. Thus, no clearly defined role could be ascribed to phenolics and peroxidase in resistance of Milicia species to P. lata-induced galling. However, polyphenol oxidase (PPO) activity was over two-fold higher in the resistant than the tolerant or susceptible progenies, suggesting that higher levels of PPO activity corresponded with an increased level of resistance to galling.
4. With further validation, PPO activity in leaves of Milicia seedlings can be used as a biomarker of resistance to Phytolyma-induced galling.

中文翻译：

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Milicia 幼苗叶片中多酚氧化酶活性的水平表明对 Phytolyma lata 诱导的瘿病的抗性

1. Phytolyma lata引起的擦伤仍然是限制西非苗圃和退化森林中Milicia物种再生的首要挑战之一。尽管种植抗植毛虫攻击的Milicia后代已被确定为长期控制害虫的机会，但缺乏用于早期检测抗性的生物标志物限制了种植抗性幼苗的选择。
2. 我们比较了抗性和易感Milicia后代中的酚类代谢物和氧化酶，目的是确定对Phytolyma诱导的幼苗瘿病抗性的潜在生物标志物。
3. 总酚类物质和邻二羟基酚类物质的水平在易感和抗性树苗之间或幼苗之间没有显着差异。同样，过氧化物酶活性在幼苗后代或幼苗之间没有差异。因此，没有明确定义的作用可以归因于酚类物质和过氧化物酶在Milicia物种对P. lata诱导的磨损的抗性中。然而，抗性后代中的多酚氧化酶 (PPO) 活性比耐受性或易感后代高两倍以上，这表明较高水平的 PPO 活性对应于抗磨损水平的增加。
4. 随着进一步的验证，在叶片PPO活性米利西亚苗可以用作抗性的生物标志物，以Phytolyma诱导的擦伤。