Arbuscular mycorrhizal symbiosis mitigates the negative effects of salinity on durum wheat

Abstract

Arbuscular mycorrhizal (AM) symbiosis is generally considered to be effective in ameliorating the plant tolerance to salt stress. Unfortunately, the comprehension of the mechanisms implicated in salinity stress alleviation by AM symbiosis is far from being complete. Thus, an experiment was performed by growing durum wheat (Triticum durum Desf.) plants under salt-stress conditions to evaluate the influence of AM symbiosis on both the plant growth and the regulation of a number of genes related to salt stress and nutrient uptake. Durum wheat plants were grown outdoors in pots in absence or in presence of salt stress and with or without AM fungi inoculation. The inoculum consisted of a mixture of spores of Rhizophagus irregularis (formerly Glomus intraradices) and Funneliformis mosseae (formerly G. mosseae). Results indicate that AM symbiosis can alleviate the detrimental effects of salt stress on the growth of durum wheat plants. In fact, under salt stress conditions mycorrhizal plants produced more aboveground and root biomass, had higher N uptake and aboveground N concentration, and showed greater stability of plasma membranes compared to non-mycorrhizal plants. Inoculation with AM fungi had no effect on the expression of the N transporter genes AMT1.1, AMT1.2, and NAR2.2, either under no-stress or salt stress conditions, probably due to the fact that plants were grown under optimal N conditions; on the contrary, NRT1.1 was always upregulated by AM symbiosis. Moreover, the level of expression of the drought stress-related genes AQP1, AQP4, PIP1, DREB5, and DHN15.3 observed in the mycorrhizal stressed plants was markedly lower than that observed in the non-mycorrhizal stressed plants and very close to that observed in the non-stressed plants. Our hypothesis is that, in the present study, AM symbiosis did not increase the plant tolerance to salt stress but instead generated a condition in which plants were subjected to a level of salt stress lower than that of non-mycorrhizal plants.

The invasive plant Solidago canadensis exhibits partial local adaptation to low salinity at germination but not at later life‐history stages

“…() found a difference in the abundance and diversity of endophytic fungi between low‐ and high‐salinity habitats, and the high‐salinity endophyte community enhanced growth of rice seedlings. Several mechanisms through which microbial symbionts confer salt tolerance to plants have been identified in other study systems (Baltruschat et al., ; Evelin et al., ; Hanin et al., ; Fileccia et al., ). However, the potential mechanisms through which soil microbial communities could have enhanced growth of S. canadensis in the present study remain unresolved.…”

“…In addition to the intrinsic genetic and physiological adaptations to salt, complex ecological processes including interactions with soil microbial communities may influence adaptation of plants to high salinity (Hanin et al., ; Fileccia et al., ). For instance, soil‐borne microbial mutualists including arbuscular mycorrhizal fungi (AMF) and symbiotic nitrogen‐fixing bacteria ( Frankia and Rhizobia ) can facilitate plant tolerance to salt stress (Hanin et al., ).…”

“…For instance, soil‐borne microbial mutualists including arbuscular mycorrhizal fungi (AMF) and symbiotic nitrogen‐fixing bacteria ( Frankia and Rhizobia ) can facilitate plant tolerance to salt stress (Hanin et al., ). Microbial mutualists can alleviate salt stress in host plants through such mechanisms as: (1) enhanced plant capacity for the uptake of water and nutrients; (2) better maintenance of membrane integrity (which facilitates compartmentation of Na + and Cl ‐ within vacuoles and selective ion intake and translocation); (3) maintenance of proper K + /Na + ratios in plant tissues (thus helping to prevent the disruption of K‐mediated enzymatic processes and the inhibition of protein synthesis); and (4) enhanced osmoregulation due to a higher accumulation of osmoprotectant solutes (e.g., proline, glycine betaine, and soluble sugars) in plant tissues (Hanin et al., ; Fileccia et al., ). Root endophytes may also confer salt tolerance by allowing symbiotic plants to activate stress response systems (e.g., increased antioxidant production) (Baltruschat et al., ).…”

Geological Characteristics of Close Geographical Related Vineyards Influence Microbiomes of Two Soil Depth Profiles With Potential Impacts on Wine Quality

“…In speci c, the Glomus genus was found to be more abundant in both CD and MLD soils, suggesting that the higher proportion of ne roots found in the deep layers are the ones more actives in recruiting microbial symbionts. It is worth noting that, Glomus species are often associated to an enhanced tolerance to salinity and water de cit stresses [66][67][68], suggesting that this genus can play important roles for the vines adaptation to the semi-arid Mediterranean areas. In parallel, Funnelliformis and Rhizophagus genera, which are well-known plant symbionts (Chitarra et al, 2016), are signi cantly over-represented in the MLS soils if compared to MLD and C soil samples.…”

Identification and Abundance of Indigenous Endomycorrhiza Isolated from Nickel Post-Mining Plantation in Sorowako

“…The symbiotic relationship between AM and plant root benefits to both, AM gains carbohydrates and energy from plant, while plant benefits from increased nutrient uptake especially P (Mau and Utami, 2014;Hosseini and Gharaghani, 2015), water level improvement and plant defence against drought stress (Sowmen et al, 2014;Augé et al, 2015), heavy metal stress (Bano and Ashfaq, 2013;Emamverdian et al, 2015), salinity stress (Yu et al, 2012;Fileccia et al, 2017), pathogenic diseases (Hemavani and Thippeswamy, 2014;Fauziyah et al, 2017), puddles (Marin's and Carrenho, 2017), and soil structure and aggregate improvement (Kimura and Scotti, 2016 ;Zhang et al, 2017). The role is strongly related to the formation of AM structures both in the roots and outside of plant roots .…”