Fungal Endophytes of Alnus incana ssp. rugosa and Alnus alnobetula ssp. crispa and Their Potential to Tolerate Heavy Metals and to Promote Plant Growth

Abstract

Soil contamination by metals is of particular interest, given that their retention times within the profile can be indefinite. Thus, phytostabilization can be viewed as a means of limiting metal toxicity in soils. Due to their ability to grow on contaminated soils, alders have repeatedly been used as key species in phytostabilization efforts. Alder ability to grow on contaminated sites stems, in part, from its association with microbial endophytes. This work emphasizes the fungal endophytes populations associated with Alnus incana ssp. rugosa and Alnus alnobetula ssp. crispa (previously A. viridis ssp. crispa) under a phytostabilization angle. Fungal endophytes were isolated from alder trees that were growing on or near disturbed environments; their tolerances to Cu, Ni, Zn, and As, and acidic pH (4.3, 3, and 2) were subsequently assessed. Cryptosporiopsis spp. and Rhizoscyphus spp. were identified as fungal endophytes of Alnus for the first time. When used as inoculants for alder, some isolates promoted plant growth, while others apparently presented antagonistic relationships with the host plant. This study reports the first step in finding the right fungal endophytic partners for two species of alder used in phytostabilization of metal-contaminated mining sites.

Is —— the rhizosphere a source of applicable multi-beneficial microorganisms for plant enhancement?

“…The capacity of endophytic fungi to increase the resistance of host plants to metals stress is also reported in several studies ( Wang et al, 2016 , Gong et al, 2017 , Lalancette et al, 2019 , Hou et al, 2020 ). Indeed, fungal endophytes populations promote plant growth and increased their tolerance to Cu, Ni, Zn, and As induced stress ( Lalancette et al, 2019 ), improved root growth and tolerance to cadmium stress by altering the soil Cd concentration and facilitating plant growth and survival under Cd stress ( Hou et al, 2020 ).…”

“…The capacity of endophytic fungi to increase the resistance of host plants to metals stress is also reported in several studies ( Wang et al, 2016 , Gong et al, 2017 , Lalancette et al, 2019 , Hou et al, 2020 ). Indeed, fungal endophytes populations promote plant growth and increased their tolerance to Cu, Ni, Zn, and As induced stress ( Lalancette et al, 2019 ), improved root growth and tolerance to cadmium stress by altering the soil Cd concentration and facilitating plant growth and survival under Cd stress ( Hou et al, 2020 ). As reported, endophytic fungus Exophiala pisciphila has been associated with maize ( Zea mays ) under also increased soil cadmium stress (0, 10, 50, 100 mg kg −1 ) and the result showed a marked tolerance to Cd, with a significant reduction in Cd phytotoxicity and a significant increase in maize growth by stimulating antioxidant systems, altering metal chemical forms into inactive cadmium, and repartitioning subcellular cadmium into the cell wall ( Wang et al, 2016 ).…”

Tree establishment on post-mining waste soils: species, density, and mixture effects

“…Alder's status is less known as a heavy metal accumulator, but it has resistance to organic and inorganic soil contaminants. It is often used for phytostabilization and as nurse species in restoration practices (Roy et al 2007;Lalancette et al 2019). White spruce, in contrast, is quite sensitive and less tolerant of heavy metal contamination.…”

Neighbours in nodules: the interactions between Frankia sp. ACN10a and non-Frankia nodular endophytes of alder

“…Their hardiness and ubiquity have led them to be used in land reclamation efforts, the control of arable land erosion, and other environmental applications (Greer et al 2005;Roy et al 2007;Quoreshi et al 2008;Lefrançois 2009;Diagne et al 2013). Their microbial symbioses with ectomycorrhizal fungi, endomycorrhizal fungi, dark septate endophytes, as well as the nitrogen-fixing bacteria of the genus Frankia play key roles in their adaptation to these harsh environments (Roy et al 2007;Bissonnette et al 2014;Lalancette et al 2019).…”