Department of Plant Physiology and Biochemistry, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 12/16, 90-237 Łódź, Poland.
Institute of Biology, Pedagogical University, Podchorążych 2, 30-084 Kraków, Poland.
Int J Mol Sci. 2020 Sep 2;21(17):6378. doi: 10.3390/ijms21176378.
We studied changes in gas exchange, photochemical activity and the antioxidant system in cucumber leaves locally infected with pv and in uninfected systemic ones. Infection-induced declined net photosynthesis rate and the related changes in transpiration rate, the intracellular CO concentration, and prolonged reduction in maximal PSII quantum yield (Fv/Fm), accompanied by an increase in non-photochemical quenching (NPQ), were observed only in the infected leaves, along with full disease symptom development. Infection severely affected the ROS/redox homeostasis at the cellular level and in chloroplasts. Superoxide dismutase, ascorbate, and tocopherol were preferentially induced at the early stage of pathogenesis, whereas catalase, glutathione, and the ascorbate-glutathione cycle enzymes were activated later. Systemic leaves retained their net photosynthesis rate and the changes in the antioxidant system were partly like those in the infected leaves, although they occurred later and were less intense. Re-balancing of ascorbate and glutathione in systemic leaves generated a specific redox signature in chloroplasts. We suggest that it could be a regulatory element playing a role in integrating photosynthesis and redox regulation of stress, aimed at increasing the defense capacity and maintaining the growth of the infected plant.
我们研究了局部感染 pv 和未感染系统的黄瓜叶片气体交换、光化学活性和抗氧化系统的变化。感染引起的净光合速率下降以及相关的蒸腾速率、胞内 CO 浓度的变化，并延长了最大 PSII 量子产量（Fv/Fm）的还原，伴随着非光化学猝灭（NPQ）的增加，仅在感染的叶片中观察到，同时出现了完全的疾病症状发展。感染严重影响了细胞水平和叶绿体中的 ROS/氧化还原平衡。超氧化物歧化酶、抗坏血酸和生育酚在发病早期优先诱导，而过氧化氢酶、谷胱甘肽和抗坏血酸-谷胱甘肽循环酶则在后期激活。系统叶片保留了它们的净光合速率，抗氧化系统的变化部分类似于感染叶片的变化，尽管它们发生得较晚且强度较小。系统叶片中抗坏血酸和谷胱甘肽的再平衡在叶绿体中产生了一个特定的氧化还原特征。我们认为，它可能是一个调节元件，在整合光合作用和应激的氧化还原调节中发挥作用，旨在提高植物的防御能力并维持感染植物的生长。
