Water Relations, Gas Exchange, Chlorophyll Fluorescence and Electrolyte Leakage of Ectomycorrhizal Pinus halepensis Seedlings in Response to Multi-Heavy Metal Stresses (Pb, Zn, Cd)

Chadlia Hachani; Mohammed S Lamhamedi; Abdenbi Zine El Abidine; Mejda Abassi; Damase P Khasa; Zoubeir Béjaoui

doi:10.3390/microorganisms10010057

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 Dec 28;10(1):57. doi: 10.3390/microorganisms10010057.

Authors

Chadlia Hachani^{1

2}, Mohammed S Lamhamedi³, Abdenbi Zine El Abidine⁴, Mejda Abassi², Damase P Khasa⁵, Zoubeir Béjaoui^{1

2}

Affiliations

¹ Faculty of Sciences of Bizerte, University of Carthage, Jarzouna 7021, Tunisia.
² 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.
³ Centre for Forest Studies, Faculty of Forestry, Geography and Geomatics, Abitibi Price Building, Laval University, Quebec, QC G1V 0A6, Canada.
⁴ National Forest School of Engineers, B.P. 5 1 1, Tabriquet, Salé 11015, Morocco.
⁵ Centre for Forest Research and Institute for Systems and Integrative Biology, Université Laval, 1030 Avenue de la Médecine, Quebec, QC G1V 0A6, Canada.

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 (Ψ_π¹⁰⁰: osmotic potential at saturation and Ψ_π⁰: 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.

Keywords: Pinus halepensis; Rhizopogon; metal stress; net photosynthesis; osmotic adjustment; tolerance.