Target or barrier? The cell wall of early- and later-diverging plants vs cadmium toxicity: differences in the response mechanisms

Abstract

Increasing industrialization and urbanization result in emission of pollutants in the environment including toxic heavy metals, as cadmium and lead. Among the different heavy metals contaminating the environment, cadmium raises great concern, as it is ecotoxic and as such can heavily impact ecosystems. The cell wall is the first structure of plant cells to come in contact with heavy metals. Its composition, characterized by proteins, polysaccharides and in some instances lignin and other phenolic compounds, confers the ability to bind non-covalently and/or covalently heavy metals via functional groups. A strong body of evidence in the literature has shown the role of the cell wall in heavy metal response: it sequesters heavy metals, but at the same time its synthesis and composition can be severely affected. The present review analyzes the dual property of plant cell walls, i.e., barrier and target of heavy metals, by taking Cd toxicity as example. Following a summary of the known physiological and biochemical responses of plants to Cd, the review compares the wall-related mechanisms in early- and later-diverging land plants, by considering the diversity in cell wall composition. By doing so, common as well as unique response mechanisms to metal/cadmium toxicity are identified among plant phyla and discussed. After discussing the role of hyperaccumulators’ cell walls as a particular case, the review concludes by considering important aspects for plant engineering.

Physiological and molecular mechanisms of heavy metal accumulation in nonmycorrhizal versus mycorrhizal plants

“…Cell walls are the first barrier against HM entry into plant cells. HM ions can bind to the functional groups of cell wall components, such as cellulose, hemicellulose, lignin, and pectin (Chen, Liu, Wang, Zhang, & Owens, ; Parrotta, Guerriero, Sergeant, Cai, & Hausman, ). Some plants can enhance their lignin biosynthesis in response to HM exposure, thereby suggesting that lignin in plant cell walls plays a role in sequestering HMs (Cheng et al, ; Elobeid, Gobel, Feussner, & Polle, ).…”

Poaceae vs. Abiotic Stress: Focus on Drought and Salt Stress, Recent Insights and Perspectives

“…It is an active structure which partakes in crucial stages of plant development and in cell signaling under exogenous stresses (Parrotta et al, 2015). A specific system of sensors ensures indeed the perception of the cell wall integrity status, which becomes perturbed upon i.e.…”

Bioindication and modelling of atmospheric deposition in forests enable exposure and effect monitoring at high spatial density across scales

“…This would help to stronger link the exposure monitoring by use of moss with effect-related monitoring of forest ecosystem condition (Saarikoski et al 2015). That approach should be added by physiological investigations on how moss species adjust their cell morphology and metabolism to environmental stress (Basile et al 2013;Müller et al 2015;Parrotta et al 2015). A spatial re-arrangement of EMS sampling sites should be discussed and an adapted sampling size should be investigated by error maps for pollutants which have toxicological and ecological effects.…”