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Hachani C, Lamhamedi MS, Zine El Abidine A, Abassi M, Khasa DP, Béjaoui Z. Water Relations, Gas Exchange, Chlorophyll Fluorescence and Electrolyte Leakage of Ectomycorrhizal Pinus halepensis Seedlings in Response to Multi-Heavy Metal Stresses (Pb, Zn, Cd). Microorganisms 2021; 10:microorganisms10010057. [PMID: 35056506 PMCID: PMC8779289 DOI: 10.3390/microorganisms10010057] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 11/20/2022] Open
Abstract
The success of mine site restoration programs in arid and semi-arid areas poses a significant challenge and requires the use of high-quality seedlings capable of tolerating heavy metal stresses. The effect of ectomycorrhizal fungi on different physiological traits was investigated in Pinus halepensis seedlings grown in soil contaminated with heavy metals (Pb-Zn-Cd). Ectomycorrhizal (M) and non-ectomycorrhizal (NM) seedlings were subjected to heavy metals stress (C: contaminated, NC: control or non-contaminated) soils conditions for 12 months. Gas exchange, chlorophyll fluorescence, water relations parameters derived from pressure–volume curves and electrolyte leakage were evaluated at 4, 8 and 12 months. Ectomycorrhizal symbiosis promoted stronger resistance to heavy metals and improved gas exchange parameters and water-use efficiency compared to the non-ectomycorrhizal seedlings. The decrease in leaf osmotic potentials (Ψπ100: osmotic potential at saturation and Ψπ0: osmotic potential with loss of turgor) was higher for M-C seedling than NM-C ones, indicating that the ectomycorrhizal symbiosis promotes cellular osmotic adjustment and protects leaf membrane cell against leakage induced by Pb, Zn and Cd. Our results suggest that the use of ectomycorrhizal symbiosis is among the promising practices to improve the morphophysiological quality of seedlings produced in forest nurseries, their performance and their tolerance to multi-heavy metal stresses.
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Affiliation(s)
- Chadlia Hachani
- Faculty of Sciences of Bizerte, University of Carthage, Jarzouna 7021, Tunisia;
- Laboratory of Forest Ecology (LR11INRGREF03), National Institute of Research in Rural Engineering, Water and Forests (INRGREF), University of Carthage, Hédi Elkarray Street, Elmenzah IV, BP 10, Ariana 2080, Tunisia;
| | - Mohammed S. Lamhamedi
- Centre for Forest Studies, Faculty of Forestry, Geography and Geomatics, Abitibi Price Building, Laval University, Quebec, QC G1V 0A6, Canada;
| | | | - Mejda Abassi
- Laboratory of Forest Ecology (LR11INRGREF03), National Institute of Research in Rural Engineering, Water and Forests (INRGREF), University of Carthage, Hédi Elkarray Street, Elmenzah IV, BP 10, Ariana 2080, Tunisia;
| | - Damase P. Khasa
- Centre for Forest Research and Institute for Systems and Integrative Biology, Université Laval, 1030 Avenue de la Médecine, Quebec, QC G1V 0A6, Canada;
| | - Zoubeir Béjaoui
- Faculty of Sciences of Bizerte, University of Carthage, Jarzouna 7021, Tunisia;
- Laboratory of Forest Ecology (LR11INRGREF03), National Institute of Research in Rural Engineering, Water and Forests (INRGREF), University of Carthage, Hédi Elkarray Street, Elmenzah IV, BP 10, Ariana 2080, Tunisia;
- Correspondence:
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Abstract
Reforestation and restoration using nursery-produced seedlings is often the most reliable way to ensure successful establishment and rapid growth of native plants. Plant establishment success—that is, the ability for the plant to develop within a set period of time with minimal further interventions needed—depends greatly on decisions made prior to planting, and yet nursery-grown plants are often produced independently of considering the range of stressors encountered after nursery production. The optimal plant or seedling will vary greatly with species and site (depending on edaphic and environmental conditions), and in having the biological capacity to withstand human and wildlife pressures placed upon vegetative communities. However, when nursery production strategies incorporate knowledge of genetic variability, address limiting factors, and include potential mitigating measures, meeting the objectives of the planting project—be it reforestation or restoration—becomes more likely. The Target Plant Concept (TPC) is an effective framework for defining, producing, and handling seedlings and other types of plant material based on specific characteristics suited to a given site. These characteristics are often scientifically derived from testing factors that are linked to outplanting success, such as seedling morphology and physiology, genetic source, and capacity to overcome limiting factors on outplanting sites. This article briefly summarizes the current knowledge drawn from existing literature for each component of the TPC framework, thereby helping land managers and scientists to meet objectives and accelerate reforestation and restoration trajectories.
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