Arbuscular Mycorrhizal Fungi Confer Salt Tolerance in Giant Reed (Arundo donax L.) Plants Grown Under Low Phosphorus by Reducing Leaf Na+ Concentration and Improving Phosphorus Use Efficiency

Abstract

Salinization is one of the major causes of agricultural soil degradation worldwide. In arid and semi-arid regions with calcareous soils, phosphorus (P) deficiency further worsens the quality of salinized soils. Nonetheless, nutrient poor soils could be suitable of producing second-generation energy crops. Due to its high biomass production, Arundo donax L. (giant reed) is one of the most promising species for energy and second-generation biofuel production. A. donax can be propagated by micropropagation, an in vitro technique that produces high number of homogeneous plantlets. However, crop establishment is often compromised due to poor plantlet acclimatization to the soil environment. Arbuscular mycorrhizal fungi (AM) are components of soil-plant systems able to increase root phosphorus uptake and to confer the plant an increase tolerance to salinity with a consequent enhancement effect of plant growth and yield. In the present study, the relative importance of the early symbiosis establishment between AM fungi and A. donax micropropagated plantlets in the response to salt stress under low phosphorus availability was determined. A commercial inoculum which contained two different AM fungi species: Rhizophagus intraradices and Funneliformis mosseae was used. AM-symbionts (AM) and non-symbionts plants were grown at two phosphorus [2.5 μM (C) and 0.5 mM (P)] and three NaCl (1, 75 and 150 mM) concentrations in a room chamber under controlled conditions. After 5 weeks, AM root colonization was 60, 26 and 15% in 1, 75 and 150 mM NaCl-treated plants, respectively. At 1 and 75 mM NaCl, AM plants showed increased growth. In all saline treatments, AM plants had decreased Na + uptake, Na + root-to-shoot translocation, Na + /K + ratio and increased P and K use efficiencies with respect to C and P plants. AM improved the nutritional status of A. donax plants by enhancing nutrient use efficiency rather than nutrient uptake. Increased phosphorus use efficiency in AM plants could have benefited ion (Na + and K + ) uptake and/or allocation and ultimately ameliorate the plant’s response to saline conditions.

Influence of Funneliformis mosseae enhanced with titanium dioxide nanoparticles (TiO2NPs) on Phaseolus vulgaris L. under salinity stress

“…AMF have been reported to be involved in nutrient use efficiency, photosynthesis and plant metabolism [ 6 ]. The symbiosis with AMF can ameliorate the plants response to salinity and have beneficial effects on plant growth and yield; this symbiosis was reported to reduce Na+ uptake and translocation and induce the uptake of K+, Ca+ and Mg+2 and stimulate the K+/Na+ and Mg+2/Na+ ratios in shoots [ 7 ].…”

Sphingobacterium sp. BHU-AV3 Induces Salt Tolerance in Tomato by Enhancing Antioxidant Activities and Energy Metabolism

“…In addition, the accumulation of Na + in leaves was less in bacterially inoculated plants compared to un-inoculated plant leaves. Several reports are available on PGPR mediation of salt tolerance in plants by reducing the transport of Na + from the roots to leaves (Yasar et al, 2006;Zhang et al, 2013;Win et al, 2018;Romero-Munar et al, 2019). ROS are induced during salt exposure and lead to oxidative stress in plant cells (Miller et al, 2010;Sharma et al, 2012).…”

Analysis of Arbuscular Mycorrhizal Fungal Inoculant Benchmarks

“…Conversely, AMF effect under saline condition is not always positive; reduced viability and symbiotic function of AMF in extreme salt conditions have been reported. Romero-Munar et al (2019) [ 74 ] reported reduced leaf growth and root colonization of A. donax (giant reed) inoculated with a commercial inoculant under moderate to high salt conditions.…”