Influence of Seed Source and Soil Contamination on Ecophysiological Responses of Lavandula pedunculata in Rehabilitation of Mining Areas

Abstract

Mining activities have turned many areas of the Iberian Pyrite Belt (IPB) into extreme environments with high concentrations of metal(loid)s. These harsh conditions can inhibit or reduce the colonization and/or development of most vegetation. However, some species or populations have developed ecophysiological responses to tolerate stress factors and contaminated soils. The main objectives of this study are: (i) to assess the differences in germination, growth, development and physiological behaviour against oxidative stress caused by metal(loid)s in Lavandula pedunculata (Mill.) Cav. from two different origins (a contaminated area in São Domingos mine, SE of Portugal and an uncontaminated area from Serra do Caldeirão, S of Portugal) under controlled conditions; and (ii) to assess whether it is possible to use this species for the rehabilitation of mine areas of the IPB. After germination, seedlings from São Domingos (LC) and Caldeirão (L) were planted in pots with a contaminated soil developed on gossan (CS) and in pots with an uncontaminated soil (US) under controlled conditions. Multielemental concentrations were determined in soils (total and available fractions) and plants (shoots and roots). Germination rate, shoot height, dry biomass and leaf area were determined, and pigments, glutathione, ascorbate and H2O2 contents were measured in plant shoots. Total concentrations of As, Cr, Cu, Pb and Sb in CS, and As in US exceed the intervention and maximum limits for ecosystem protection and human health. The main results showed that L. pedunculata, regardless of the seed origin, activated defence mechanisms against oxidative stress caused by high concentrations of metal(loid)s. Plants grown from seeds of both origins increased the production of AsA to preserve its reduction levels and kept the contents of GSH stable to maintain the cell’s redox state. Plants grown from seeds collected in non-contaminated areas showed a high capacity for adaptation to extreme conditions. This species showed a greater growth capacity when seeds from a contaminated area were sown in uncontaminated soils. Thus, L. pedunculata, mainly grown from seeds from contaminated areas, may be used in phytostabilization programmes in areas with soils with high contents of metal(loid)s.

Assembly and Function of Seed Endophytes in Response to Environmental Stress

“…Lavandula pedunculata seeds collected in soils contaminated with high concentrations of metals show greater growth ability than those collected in uncontaminated areas, because endophytes colonizing in the seeds may maintain high GSH content under high metal stress to reduce oxidative stress and have potential environmental resilience [ 97 ]. When Agrostis capillaris grows in Cd/Ni-contaminated soil for a long time, its seed endophytic bacteria, Bacillus sp.…”

“…Despite the growing evidence that seed endophytes play an important role in host plants for resisting environmental stress [ 78 , 97 , 99 , 103 ], we still face many limitations and challenges in carrying out large-scale applications in the field of sustainable agriculture and natural ecosystems. In particular, there are several questions we must answer thus far, including: how can the target strains be obtained effectively and efficiently?…”

“…That is why endophytes in seeds have been continuously discovered by means of high-throughput sequencing techniques, but some species fail to be isolated and cultured from seeds [ 1 , 20 , 21 ]. To obtain a target strain, it may be effective to use selective media to cultivate species (or strains) that adapt to environmental stress [ 20 , 57 , 97 ]. Moreover, the current research focuses on seed bacteria rather than seed fungi.…”

Unveiling a Technosol-Based Remediation Approach for Enhancing Plant Growth in an Iron-Rich Acidic Mine Soil from the Rio Tinto Mars Analog Site

“…Mine soils pose significant obstacles to conventional direct sowing practices due to their inherently challenging environmental conditions (e.g. Arenas-Lago et al, 2022;Carvalho et al, 2022;Mourinha et al, 2022), including elevated trace element content, acidic pH, and poor nutrient availability. These factors impede the establishment of sustainable plant populations, leading to limited success with direct sowing methods.…”