Selection of arbuscular mycorrhizal fungal strains to improve Casuarina equisetifolia L. and Casuarina glauca Sieb. tolerance to salinity

Abstract

& Key message Selection of the best salt-tolerant combination of Casuarina sp. and arbuscular mycorrhizal fungi (AMF) is one of the key criteria for successful setup of saline land rehabilitation program. & Context Land salinization is a serious problem worldwide that mainly leads to soil degradation and reduces crop productivity. These degraded areas could be rehabilitated by planting salt-tolerant species like Casuarina glauca Sieb. and Casuarina equisetifolia L. These are pioneer plants, able to form symbiotic associations with arbuscular mycorrhizal fungi (AMF), ectomycorrhizal fungi (EMF), and nitrogen-fixing bacteria. & Aims The aim of this study was to select the highest salt-tolerant combination of Casuarina/AMF that can be used for the rehabilitation of lands degraded by salinity. & Methods C. equisetifolia and C. glauca were grown in sandy sterile soil in the greenhouse and inoculated separately with Rhizophagus fasciculatus (Thaxt.) C. Walker & A. Schüßler, Rhizophagus aggregatus (N.C. Schenck & G.S. Sm.) C. Walker, and Rhizophagus intraradices (N.C. Schenck & G.S. Sm.) C. Walker & A. Schüßler. After confirming the establishment of a symbiosis, the plants were watered with gradually increasing concentrations of saline solution. After harvest, size and biomass of the seedlings, root colonization by AMF, and AMF metabolic activities were evaluated.

Effect of Plant Growth Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi (AMF) on Salt Stress Tolerance of Casuarina obesa (Miq.)

“…The higher frequencies and intensities in co-inoculated P.agg + Rf plants would explain the salt tolerance of this strain. The work of Djighaly et al (2018) showed significant metabolic activity of R. fasciculatus at 300 mM NaCl. But also to the additional effect of PGPR which improves the phosphate nutrition of the plant (Egamberdieva et al, 2019).…”

“…This effect was related to an increase in K+ content accompanied by an effective decrease in Na+ in plant tissues. The positive effect co-inoculation P. agg + Rf on growth parameters could be explained by the fact that P. agglomerans, is a halophilic, nitrogen-fixing and phosphate-solubilizing strain, capable of producing of indole acetic acid (AIA) up to 600 mM NaCl (Hasfa, 2014) and AMF (R. fasciculatus) in improving salt tolerance stress among Casuarina species (Djighaly et al, 2018). In the presence of salt, these microorganisms participate in the selective absorption of ions such as phosphorus, nitrogen and magnesium and in the reduction of Na+ ion absorption (Giri and Mukerji, 2004;Chen et al, 2014;Paul and Sinha, 2017).…”

“…After 3 weeks of acclimatization, the control plants were watered with 0 mM and the stressed plants with 150 and 300 mM of NaCl. The choice of these concentrations was made on the basis of previous studies on Casuarina by Djighaly et al (2018).…”

Transcriptome and structure analysis in root of Casuarina equisetifolia under NaCl treatment

“…Meanwhile, 15 PCD-related genes were induced by SA or JA to participate in the salt stress response. Interestingly, selection of appropriate fungal strains is crucial for improving C. equisetifolia performance in saline soils ( Djighaly et al, 2018 ). The effect of Frankia symbiosis on salt tolerance of C. equisetifolia will be our next research focus.…”

Roles of Arbuscular Mycorrhizal Fungi on Plant Growth and Performance: Importance in Biotic and Abiotic Stressed Regulation

“…Their contribution to the improvement of the growth of several plant species under saline conditions is well known [107,108] (Table 4). This is mainly related to a combination of biochemical, physiological, and nutritional effects [97,[109][110][111][112][113][114][115][116]. Among the mechanisms involved in salinity tolerance in AMF inoculated plants, we have the enhancement of water absorption capacity and nutrient uptake, the accumulation of osmoregulators like proline and sugars [105], the ionic homeostasis [87,117], and the reduction in Na + and Cl − uptake [118].…”