The association between reactive oxygen species (ROS) production and potato resistance to the hemibiotrophic pathogen Phytophthora infestans is poorly understood. In this study, the concentrations of hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and soluble phenolics, as well as the activities of superoxide dismutase, catalase, and ascorbate peroxidase were measured during the early biotrophic and late necrotrophic stages of P. infestans infection on resistant and susceptible ‘Ovatio’ and ‘Bintje’ potato plants, respectively. Pathogen biomass was examined using semi-quantitative RT-PCR. Late blight (LB) severity was also evaluated. The LB severity in Ovatio was lower than that in Bintje, irrespective of the evaluation time. Moreover, in both cultivars, various biochemical defense responses occurred following pathogen infection. The susceptible cultivar activated defense responses at the later pathogen infection stages, resulting in higher concentrations of H 2 O 2 and greater MDA content, with lower activity of antioxidant enzymes and phenolic content. These responses were accompanied by the necrotrophic phase, leading to extensive necrotic lesions on leaves. In contrast, fast hypersensitive-like lesions, an early peak in H 2 O 2 concentration, low cell membrane integrity during the biotrophic phase, and a more efficient antioxidative system effectively restricted pathogen colonization before the transition to the necrotrophic phase in the resistant cultivar. These results suggest that LB resistance or susceptibility is regulated by a balance between the induction of ROS/antioxidants (intensity and timing) and the trophic phase of P. infestans .

中文翻译：

---

活性氧的早期产生与有效的抗氧化系统相结合在马铃薯晚疫病抗性中发挥作用

活性氧 (ROS) 的产生与马铃薯对半生物营养型病原体 Phytophthora infestans 的抗性之间的关联知之甚少。在这项研究中，过氧化氢 (H 2 O 2 )、丙二醛 (MDA) 和可溶性酚类物质的浓度，以及超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶的活性在早期生物营养和晚期坏死营养阶段进行了测量。 P. infestans 分别对抗性和易感 'Ovatio' 和 'Bintje' 马铃薯植物的感染。使用半定量RT-PCR检查病原体生物量。还评估了晚疫病 (LB) 的严重程度。无论评估时间如何，Ovatio 的 LB 严重程度都低于 Bintje。此外，在这两个品种中，病原体感染后发生了各种生化防御反应。易感品种在病原体感染后期激活防御反应，导致 H 2 O 2 浓度更高，MDA 含量更高，抗氧化酶活性和酚类含量更低。这些反应伴随着坏死阶段，导致叶子上出现广泛的坏死病变。相比之下，快速的过敏样病变、H 2 O 2 浓度的早期峰值、生物营养阶段的低细胞膜完整性以及更有效的抗氧化系统有效地限制了病原体在抗性品种过渡到坏死营养阶段之前的定植。这些结果表明 LB 抗性或易感性受 ROS/抗氧化剂的诱导（强度和时间）与 P. infestans 的营养阶段之间的平衡调节。