Physiological responses of "Jarilla hembra" (Larrea divaricata) to plumbum contaminated area: Multivariate analysis of stress variables

Abstract

Larrea divaricata is a native plant adapted to a wide range of arid environments. Our group is assessing this specie as phytoremediator for lead (Pb) contaminated areas, so, the aim is to determine its physiological response under stress caused by Pb bullets of a shooting range field. Plants growing at greenhouse were planted in soils with 0 and 1000 ppm Pb (0 Pb and 1000 Pb) in the same field, and they were compared with plants that continued at the greenhouse (GH). After 6 months, samples of aerial parts were collected for lipid peroxidation (LP) analysis and determination of catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GOPX) activity. Results were analyzed by uni (ANOVA and Tukey test) and multivariate statistics (PCA). Univariate statistics determined no significant differences in LP between treatments although plants 1000 Pb showed a significant decrease of CAT, APX, and GOPX activity respect to plants 0 Pb. The behavior of GH plants was similar to 0 Pb of field plants, although univariate statistical did not show significant differences between GH and 1000 Pb plants either. Nevertheless, PCA showed in scores plot of PCA three different groups: 0 Pb, 1000 Pb and GH. Loadings plot showed that 0 Pb was differentiated from the other groups by the influence of APX and GOPX variables in PC1, while 1000 Pb and GH were differentiated by the influence of LP and CAT variables in PC2. Results of PCA indicate that the activity of CAT, APX, and GOPX is reduced in 1000 Pb treatment on field respect to 0 Pb and GH. In addition, lipid peroxidation is minor in GH plants than both field treatments (0 Pb and 1000 Pb) while CAT activity is higher in GH than in field treatments. Effects of oxidative stress are evident at field treatments in comparison with GH plants as well as the decrease of antioxidant response in plants under Pb contamination respect to both controls (0 Pb and GH). Multivariate analysis was capable of differentiating three growth conditions and determine their physiological status. In conclusion, although the first pilot essay shows the effects of Pb over L. divaricata physiology, more studies are needed to determine whether L. divaricata is potentially useful as a phytoremediator plant.A166