Influence of drought and salt stress on the growth of young Populus nigra ‘Italica’ plants and associated mycorrhizal fungi and non-mycorrhizal fungal endophytes

Abstract

Populus nigra ‘Italica’ (Lombardy poplar) is a breeding cultivar of black poplar, widely used as a street tree or windbreak, often exposed to salinity and limited water availability. Populus roots can develop dual mycorrhizal associations with ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi, and with non-mycorrhizal fungal endophytes (FE). The symbiotic fungi may alleviate the effects of adverse environmental conditions. We investigated the performance (growth and symbiotic associations) of one-year-old Populus nigra ‘Italica’ grown from woody cuttings in soil from natural poplar habitat and subjected to water scarcity and soil salinity (50 mM NaCl, 150 mM NaCl, 250 mM NaCl). With increasing soil salinity, a decrease in the growth parameters of the aboveground parts of the poplar plantlets and their fine roots were found; however, the roots were more resistant to the stress factors analyzed than the shoots. ECMF, AMF, and non-mycorrhizal FE were all tolerant to increased salt levels in the soil, and the ECM abundance was significantly higher under conditions of mild salinity (50 mM NaCl, 150 mM NaCl) compared to the control plants and those treated with 250 mM NaCl. Our results indicated that enhanced soil salinity increased the content of sodium and chlorine in leaves, but did not affect significantly the concentrations potassium, magnesium, calcium, phosphorus, or nitrogen. Significant accumulation of proline in leaves suggest salt stress of P. nigra ‘Italica’ treated with 250 mM NaCl and contribution of proline to the plant defense reactions.

Mycorrhizae set the stage for plants to produce a higher production of biomolecules and stress-related metabolites: a sustainable alternative of agrochemicals to enhance the quality and yield of beetroot (Beta vulgaris L.)

“…In the same way, proline content was measured. It is well known that proline is the major osmolyte, which plays an important role in maintaining the osmotic balance of the cell during various stresses, and different mycorrhizae boost the immune system of the plants by enhancing the level of proline in both unstressed and stressed conditions (Ortiz et al, 2015 ; Kulczyk-Skrzeszewska and Kieliszewska-Rokicka, 2022 ; Zahedi et al, 2022 ). Here, after treatment with mycorrhizae, it was found that proline concentration was increasing with the increasing mycorrhizal combination.…”

Enhancing Salt Tolerance in Poplar Seedlings through Arbuscular Mycorrhizal Fungi Symbiosis

“…AMF primarily alleviated the adverse effects of salt stress on AMF-inoculated Zelkova serrata seedlings by reducing Na + content, increasing P, K + , and Mg 2+ concentrations, and enhancing leaves’ photosynthetic levels and biomass accumulation [ 18 ]. The dual mycorrhizal association with ectomycorrhizal fungi (ECM), arbuscular mycorrhizal fungi, and non-mycorrhizal endophytes (FE) enhances poplar stress resistance [ 19 ]. It is important to note that ECM dominates in more mature trees, whereas AMF is present throughout the growth stages of poplar, especially at the seedling stage [ 20 ].…”

Plant Microbiome and Mycorrhizal Fungi

“…However, some studies have found that this interaction is closely related to mycorrhizal helper bacteria (MHB). Mycorrhizal helper microorganism is a kind of special rhizosphere and endophyte that can specifically bind to mycorrhizal fungi, promote mycorrhizal fungi infection to the host, and promote plant growth and development [7,8]. The interaction of mycorrhizal fungi and auxiliary microorganisms can promote plant growth, reduce the occurrence of soil-borne diseases, and improve the availability of nutrients in soil and plant absorption rate [9][10][11].…”