Tagetes minuta L. Variability in Terms of Lead Phytoextraction from Polluted Soils: Is Historical Exposure a Determining Factor?

MIRANDA PAZCEL, ELIANA M.; WANNAZ, EDUARDO D.; PIGNATA, MARÍA L.; SALAZAR, MARÍA J.

Environmental Processes

Springer

Año: 2018 vol. 5 p. 243 - 259

2198-7491

Tagetes minuta L. is a plant which accumulates Pb under certain conditions, makingit a candidate for phytoextraction projects because it also produces marketable essential oilswithout detectable Pb levels. Although extraction efficiency has been shown to significantlyvary between individuals, these results have been obtained using only historically exposedpopulations, which leads to the questions: Is the ability to tolerate and accumulate Pb aproperty of the species? Or is it a characteristic of some individuals from a historically exposedpopulation? In this context, a greenhouse experiment was performed to analyse the intrapopulation and interpopulation variability in response to Pb among individuals from historicallyunexposed and exposed populations. In addition, we also attempted to identify relationshipsbetween certain capabilities (toleration and accumulation of Pb) and the physiological parameters related to oxidative stress or the volatile compounds of the essential oils. The Pbconcentration was determined by total reflection X-ray fluorescence, physiological parameterswere obtained by spectrophotometry, and essential oils were analysed by gas chromatography.The results demonstrated that adequate tolerance and accumulation capabilities are present inT. minuta, irrespective of the exposure history. These findings may be associated to a hormesisresponse, which includes enhancement of pigments, biomass production and the uptake ofother heavy metals such as micronutrients. Nevertheless, the historically exposed populationhad a better tolerance to Pb, since it presented defence characteristics reflected in the essentialoil composition and in the avoidance of damage at the lipid peroxidation level after Pb uptake