Department of Botany, Universität Innsbruck, Sternwartestrasse 15, Innsbruck A-6020, Austria.
Tree Physiol. 2023 Oct 8;43(10):1745-1757. doi: 10.1093/treephys/tpad084.
Abiotic factors such as water and nutrient availability can exert a dominant influence on the susceptibility of plants to various pathogens. Effects of abiotic environmental factors on phenolic compound concentrations in the plant tissue may represent one of the major underlying mechanisms, as these compounds are known to play a substantial role in plant resistance to pests. In particular, this applies to conifer trees, in which a large range of phenolic compounds are produced constitutively and/or induced by pathogen attack. We subjected Norway spruce saplings to water limitation and elevated nutrient supply over 2 years and subsequently controlled infection with the needle rust Chrysomyxa rhododendri (DC.) de Bary and analysed both constitutive and inducible phenolic compound concentrations in the needles as well as the degree of infection. Compared with the control group, both drought and fertilization profoundly modified the constitutive and pathogen-induced profiles of phenolic compounds, but had little impact on the total phenolic content. Fertilization predominantly affected the inducible phenolic response and led to higher infection rates by C. rhododendri. Drought stress, in contrast, mainly shaped the phenolic profiles in healthy plant parts and had no consequences on the plant susceptibility. The results show that specific abiotic effects on individual compounds seem to be decisive for the infection success of C. rhododendri, whereby the impaired induced response in saplings subjected to nutrient supplementation was most critical. Although drought effects were minor, they varied depending on the time and length of water limitation. The results indicate that prolonged drought periods in the future may not significantly alter the foliar defence of Norway spruce against C. rhododendri, but fertilization, often propagated to increase tree growth and forest productivity, can be counterproductive in areas with high pathogen pressure.
非生物因素，如水分和养分的可利用性，可能对植物对各种病原体的易感性产生主导影响。非生物环境因素对植物组织中酚类化合物浓度的影响可能是主要的潜在机制之一，因为这些化合物在植物抵御害虫方面起着重要作用。特别是对于针叶树，其中大量的酚类化合物是组成型产生的和/或由病原体攻击诱导产生的。我们在两年的时间里，让挪威云杉幼苗经受水分限制和养分供应增加的处理，随后控制叶锈病（Chrysomyxa rhododendri (DC.) de Bary）的感染，并分析针叶中的组成型和诱导型酚类化合物浓度以及感染程度。与对照组相比，干旱和施肥都深刻地改变了组成型和诱导型酚类化合物的特征，但对总酚含量几乎没有影响。施肥主要影响诱导性酚类物质的反应，导致 C. rhododendri 的感染率增加。相比之下，干旱胁迫主要影响健康植物部分的酚类特征，对植物的易感性没有影响。研究结果表明，对个别化合物的特定非生物效应似乎对 C. rhododendri 的感染成功具有决定性意义，而在接受养分补充的幼苗中，受损的诱导反应最为关键。尽管干旱的影响较小，但它们随水分限制的时间和长度而变化。结果表明，在未来，长时间的干旱期可能不会显著改变挪威云杉对 C. rhododendri 的叶片防御，但施肥，通常被推广以增加树木生长和森林生产力，在高病原体压力的地区可能会适得其反。
