Arsenic phytoextraction and hyperaccumulation by fern species

Abstract

Arsenic (As) is an ubiquitous trace metalloid found in all environmental media. Its presence at elevated concentrations in soils derives from both anthropogenic and natural inputs. Arsenic is a toxic and carcinogenic element, which has caused severe environmental and health problem worldwide. Technologies currently available for the remediation of arsenic-contaminated sites are expensive, environmentally disruptive, and potentially hazardous to workers. Phytoextraction, a strategy of phytoremediation, uses plants to clean up contaminated soils and has been successfully applied to arsenic contaminated soils. It has the advantage of being cost-effective and environmentally friendly. A major step towards the development of phytoextraction of arsenic-impacted soils is the discovery of the arsenic hyper accumulation in ferns, first in Pteris vittata, which presented an extraordinary capacity to accumulate 2.3% arsenic in its biomass. Another fern, Pityrogramma calomelanos was found to exhibit the same hyperaccumulating characteristics. After that, screening experiments have revealed that the Pteris genus is really unique in that many species have the potential to be used in phytoextraction of arsenic. In general, these plants seem to have both constitutive and adaptive mechanisms for accumulating or tolerating high arsenic concentration. In the past few years, much work has been done to understand and improve the hyperaccumulating capability of these amazing plants. In particular, the field of molecular biology seems to hold the key for the future of the phytoremediation. Key words: environmental contamination, hyperaccumulator plants, phytoremediation FITOEXTRAÇÃO E HIPERACUMULAÇÃO DE ARSÊNIO POR ESPÉCIES DE SAMAMBAIASRESUMO: O arsênio e um metalóide traço encontrado basicamente em todos os ambientes. Elevadas concentrações de arsênio no solo podem acontecer naturalmente devido ao intemperismo de rochas ricas em arsênio, como também de atividades antropogênicas. O arsênio é um elemento tóxico e cancerígeno. Em muitas partes do mundo, a contaminação pelo arsênio tem causado problemas ambientais e de saude. As técnicas disponíveis para a remediação do arsênio são economicamente proibitivas, destroem a paisagem natural e ainda podem afetar a saúde de pessoas diretamente envolvidas no processo. A fitoextração, uma das estratégias da fitoremediação, utiliza plantas para descontaminar solos e tem sido aplicada com sucesso em solos contaminados com arsênio e outros elementos. Dentre muitas vantagens, essa técnica tem baixo custo quando comparada com as convencionais. Um ponto chave no desenvolvimento da fitoextração foi a constatação de que samambaias hiperacumulam arsênio. Primeiro, em Pteris vittata, que apresentou extraordinária capacidade para remover arsênio do solo, concentrando 2.3% do arsênio na biomassa. Em seguida, foi observado que a samambaia Pityrogramma calomelanos possui capacidade semelhante para acumular arsênio. Essa característica peculiar foi observada em outras samambaias do genero Pteris. Em...

Arsenic present in the soil‐vine‐wine chain in vineyards situated in an old mining area in Trentino, Italy

“…These BF values are really low, very far from values >1 considered typical of tolerant or hyperaccumulator plants [7,33]. Bioconcentration factors of a comparable order of magnitude are normally given for mineral elements that are hardly taken up by plants, such as rare earth elements [34].…”

Espécies tropicais de pteridófitas em associação com fungos micorrízicos arbusculares em solo contaminado com arsênio

“…6,[30][31][32] Em geral, o As inibe o metabolismo na maioria das plantas. 33 Mais especificamente, o arsenato pode provocar a fosforilação oxidativa e a produção de ATP 32,34 e, também, a capacidade de substituir o P em várias reações. 35 O arsenito afeta a função de enzimas e proteínas pela ligação a grupos sulfidrílicos.…”

Rhizoremediation of metals: harnessing microbial communities

“…The addition of bacteria to surface-sterilized seeds of T. caerulescens sown in autoclaved soil increased the Zn concentration in shoots 2-fold as compared to axenic controls; the total accumulation of Zn was enhanced 4-fold [42,64]. Heavy metals stimulate the production of siderophores eg., under cadmium stress the synthesis of phytoharmones are triggered that ended up in higher uptake of metals [59].…”

“…This alleviates the toxicity of plants [43]. More research is needed to investigate further the low molecular weight thiols [42]. Research is also underway to study the genetic and functional characters of the rhizosphere microbial communities in P.vittata.…”