Subcellular Alterations Induced by Cyanotoxins in Vascular Plants—A Review

Abstract

Phytotoxicity of cyanobacterial toxins has been confirmed at the subcellular level with consequences on whole plant physiological parameters and thus growth and productivity. Most of the data are available for two groups of these toxins: microcystins (MCs) and cylindrospermopsins (CYNs). Thus, in this review we present a timely survey of subcellular cyanotoxin effects with the main focus on these two cyanotoxins. We provide comparative insights into how peculiar plant cellular structures are affected. We review structural changes and their physiological consequences induced in the plastid system, peculiar plant cytoskeletal organization and chromatin structure, the plant cell wall, the vacuolar system, and in general, endomembrane structures. The cyanotoxins have characteristic dose-and plant genotype-dependent effects on all these structures. Alterations in chloroplast structure will influence the efficiency of photosynthesis and thus plant productivity. Changing of cell wall composition, disruption of the vacuolar membrane (tonoplast) and cytoskeleton, and alterations of chromatin structure (including DNA strand breaks) can ultimately lead to cell death. Finally, we present an integrated view of subcellular alterations. Knowledge on these changes will certainly contribute to a better understanding of cyanotoxin–plant interactions.

Microcystin-LR, a Cyanobacterial Toxin, Induces DNA Strand Breaks Correlated with Changes in Specific Nuclease and Protease Activities in White Mustard (Sinapis alba) Seedlings

“…Throughout our study we concentrated on 4 days of MC-LR treatments, because this time frame is enough to induce most of the PCD symptoms in mustard seedlings (time-course results shown for neutral nucleases in this study; [4]).…”

“…The release of MCs into water bodies at high concentrations affects not only aquatic ecosystems but also human and animal health [2]. Concerning vascular plants, it affects not only aquatic macrophytes naturally co-existing with toxic cyanobacteria but terrestrial crops (via spray irrigation with contaminated waters) as well [3,4]. The biochemical targets of MC-LR are mainly type 1 and 2A protein phosphatases [5].…”

“…The biochemical targets of MC-LR are mainly type 1 and 2A protein phosphatases [5]. Meanwhile, toxin exposures in the long-term and/or their relatively high concentrations induce a wide variety of stress responses, one of the most important being the induction of cell death [4]. Therefore, cellular/biochemical studies of MC-LR toxicity are important not only for using the toxin as a tool for a better understanding of protein phosphatase functioning but also for understanding its harmful environmental effects.…”

“…Concerning vascular plants, the particular effects of cyanotoxins may vary among species, but there are cell death symptoms detected in nearly all species studied. The most important are: nuclear condensation and fragmentation, the formation of micronuclei, DNA degradation/strand breaks related to nuclease activities and typical symptoms of necrosis [4,[7][8][9]. However, there is still a need for further research to achieve a better understanding of MC-LR-plant interactions in this context.…”

Cyanobacteria: A Natural Source for Controlling Agricultural Plant Diseases Caused by Fungi and Oomycetes and Improving Plant Growth

“…In this review, the toxic effect of cyanotoxins is mainly focused on plants. There is an increasing attention in the use of cyanotoxin-contaminated surface waters for agricultural practices [65,68,69]. This issue may raise concerns about possible effects on crop growth and development due to bioaccumulation of toxins in the crops and thereby, the food security.…”