Impacts of Microcystins on Morphological and Physiological Parameters of Agricultural Plants: A Review

Abstract

Cyanobacteria are a group of photosynthetic prokaryotes that pose a great concern in the aquatic environments related to contamination and poisoning of wild life and humans. Some species of cyanobacteria produce potent toxins such as microcystins (MCs), which are extremely aggressive to several organisms, including animals and humans. In order to protect human health and prevent human exposure to this type of organisms and toxins, regulatory limits for MCs in drinking water have been established in most countries. In this regard, the World Health Organization (WHO) proposed 1 µg MCs /L as the highest acceptable concentration in drinking water. However, regulatory limits were not defined in waters used in other applications/activities, constituting a potential threat to the environment and to human health. Indeed, water contaminated with MCs or other cyanotoxins is recurrently used in agriculture and for crop and food production. Several deleterious effects of MCs including a decrease in growth, tissue necrosis, inhibition of photosynthesis and metabolic changes have been reported in plants leading to the impairment of crop productivity and economic loss. Studies have also revealed significant accumulation of MCs in edible tissues and plant organs, which raise concerns related to food safety. This work aims to systematize and analyze the information generated by previous scientific studies, namely on the phytotoxicity and the impact of MCs especially on growth, photosynthesis and productivity of agricultural plants. Morphological and physiological parameters of agronomic interest are overviewed in detail in this work, with the aim to evaluate the putative impact of MCs under field conditions. Finally, concentration-dependent effects are highlighted, as these can assist in future guidelines for irrigation waters and establish regulatory limits for MCs.

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

“…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. Regarding the effects of cyanotoxins on plants, large amount of recent scientific articles have been published to explain the biochemical and physiological alterations induced by microcystins and cylindrospermopsins [65,[68][69][70][71]. Structural and physiological alterations have crucial consequences on plant growth and on the crop productivity.…”

“…Structural and physiological alterations have crucial consequences on plant growth and on the crop productivity. The cyanotoxins induce considerable modification in the organization of plant-specific structures differently by the effects observed on animal/human cells [69,71]. A meta-analysis study on data published up to now on 35 crop plants, found that leafy greens, such as parsley and cabbage, accumulate about three times more microcystins in their edible portion than other agricultural crops [72].…”

Subcellular Alterations Induced by Cyanotoxins in Vascular Plants—A Review

“…Since the pioneering work of [ 13 ], a huge amount of work has demonstrated the detrimental effects of cyanotoxins on aquatic plants and terrestrial crops (see the review of [ 14 ] in this topical issue and [ 15 ] for examples). For vascular plants, most phytotoxicity data are available for MCs and CYN and thus we concentrate mainly on these two metabolites.…”

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

“…Microcystin-LR (MC-LR) belongs to a family of toxic heptapeptides produced by several cyanobacterial genera [1]. The producers require relatively warm water, and global warming together with freshwater eutrophication induces their overproduction [1][2][3]. The release of MCs into water bodies at high concentrations affects not only aquatic ecosystems but also human and animal health [2].…”

“…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].…”