Chronic ionizing radiation suppresses resistance to pathogens in aquatic plants without substantial oxidative stress

Chronic ionizing radiation imposes direct and indirect damage on plants that could modify their morphology, biochemistry, physiology, as well as responses to biotic agents. Plants experience elevated levels of DNA damage and reactive oxygen species; thus, they adjust cellular homeostasis. Aquatic ecosystems in Chornobyl zone, a major radiological disaster site, are contaminated by harmful radionuclides. This study focused on changes in the proteome of leaves as well as carbonylated proteins, which might explain the biochemical mechanisms responsible for the susceptibility of a wild aquatic plant (common reed, Phragmites australis) grown in Chornobyl zone to biotic stress. The fungal infection assay indicated that life in a radionuclide-contaminated environment compromised plant immunity. The protein profiling identified 1,867 proteins; among them, 174 were differentially accumulated. We selected several dozen proteins with consistently higher and lower abundance in the samples from areas around the contaminated lakes by hierarchical clustering. Discordant expression of coding genes pointed to posttranscriptional regulation. Furthermore, the quantification of antioxidant enzyme activities (glutathione reductase, ascorbate peroxidase, catalase, and glutathione S-transferase) and carbonylated proteins rebutted the idea about substantial oxidative stress in chronically irradiated plants. We advocate the necessity to consider plausibly increased pathogen sensitivity while developing policies for the management of radionuclide-contaminated areas.