Effects of microcystin-LR and cylindrospermopsin on plant-soil systems: A review of their relevance for agricultural plant quality and public health

Abstract

Toxic cyanobacterial blooms are recognized as an emerging environmental threat worldwide. Although microcystin-LR is the most frequently documented cyanotoxin, studies on cylindrospermopsin have been increasing due to the invasive nature of cylindrospermopsin-producing cyanobacteria. The number of studies regarding the effects of cyanotoxins on agricultural plants has increased in recent years, and it has been suggested that the presence of microcystin-LR and cylindrospermopsin in irrigation water may cause toxic effects in edible plants. The uptake of these cyanotoxins by agricultural plants has been shown to induce morphological and physiological changes that lead to a potential loss of productivity. There is also evidence that edible terrestrial plants can bioaccumulate cyanotoxins in their tissues in a concentration dependent-manner. Moreover, the number of consecutive cycles of watering and planting in addition to the potential persistence of microcystin-LR and cylindrospermopsin in the environment are likely to result in groundwater contamination. The use of cyanotoxin-contaminated water for agricultural purposes may therefore represent a threat to both food security and food safety. However, the deleterious effects of cyanotoxins on agricultural plants and public health seem to be dependent on the concentrations studied, which in most cases are non-environmentally relevant. Interestingly, at ecologically relevant concentrations, the productivity and nutritional quality of some agricultural plants seem not to be impaired and may even be enhanced. However, studies assessing if the potential tolerance of agricultural plants to these concentrations can result in cyanotoxin and allergen accumulation in the edible tissues are lacking. This review combines the most current information available regarding this topic with a realistic assessment of the impact of cyanobacterial toxins on agricultural plants, groundwater quality and public health.

Cytotoxic and morphological effects of microcystin‐LR, cylindrospermopsin, and their combinations on the human hepatic cell line HepG2

“…Regarding to MC‐LR, there are several studies in the scientific literature in HepG2 cells but most of them used lower concentrations than in the present work as they were focused on the study of toxicity mechanisms and not in deriving EC 50 values (ie, Refs. ). Chong et al concluded that MC‐LR did not cause cytotoxic effects in HepG2 cells and other hepatic cell line in 48–96 h of exposure to concentrations up to 100 μg/mL.…”

“…The presence of two or more cyanobacterial species in water reservoirs is a common finding around the world . Among these cyanobacteria, many are capable to produce cyanotoxins, such as MC‐LR and CYN, which can cause harmful effects in animals, plants, and humans . However, the potential interaction between MC‐LR and CYN has not been deeply explored in vitro, although it is of interest due to their co‐occurrence …”

“…These studies are related with waterbodies monitoring in order to manage cyanobacterial blooms appearances as well as the toxins concentration reached. The little research published so far on the toxic effects of MCs/CYN combinations is mainly focused on plants . However, Hercog et al evaluated in vitro the genotoxic potential of the each toxin alone and their combination on HepG2 cells, concluding that MC‐LR did not show a role on the deregulation of the genes investigated, attributing all the effect to CYN.…”

Vitamin C protects porcine oocytes from microcystin-LR toxicity during maturation

“…They can bioaccumulate in aquatic animals owing to their ability to resist degradation under conditions found in most natural water ways (near-neutral pH) and are also resistant to high temperatures. [5] Microcystinleucine-arginine (MC-LR) is one of the most abundant and harmful microcystins [6,7]. It is a potent hepatotoxin that has been linked to the development of primary liver cancer and is classi ed as a potential human carcinogen (Group 2B) by the International Agency for Research on Cancer (IARC) [8][9][10].…”

Food crops irrigated with cyanobacteria-contaminated water: an emerging public health issue in Canada

“…Some studies were conducted under hydroponic conditions (Gutierrez-Praena et al, 2014), whereas others used potted soil or sand (Järvenpää et al, 2007;Crush et al, 2008;Hereman and Bittencourt-Oliveira, 2012;Bittencourt-Oliveira et al, 2016;Cordeiro-Araújo et al, 2016;Machado et al, 2017a). Soil can retain up to 57% of the toxin bioavailable to the plant (Machado et al, 2017b); however, there is a lack of controlled studies conducted under field conditions using ecologically relevant concentrations.…”