Arbuscular Mycorrhizal Colonization Promotes the Tolerance to Salt Stress in Lettuce Plants through an Efficient Modification of Ionic Balance

Abstract

Soil salinity is the biggest problem which hinders the productivity of agricultural crops, causing adverse effects on plant growth and development. In this regard, it has been shown that the arbuscular mycorrhizal fungi (AMF) can establish a symbiosis with most agricultural plants improving water and nutrient absorption under salinity stress conditions. The functional contribution of AMF strains (Claroideoglomus claroideum (Cc) and a native consortium of AMF (HM) isolated from saline soils) on the growth and nutrition of lettuce plants (Lactuca sativa var. longifolia) was evaluated under increasing salt stress conditions (0, 40, and 80 mM NaCl). At 60 days of growth, biomass production, nutrient content (N, P), ions (Ca 2+ , Mg 2+ , Na + , K +), chlorophyll, proline content, and AMF propagules were evaluated. The highest growth was observed in plants inoculated with Cc, which produced a higher percentage of root colonization and hyphal length at all levels of salinity, compared to plants inoculated with HM or non-inoculated plants. These results were directly related to higher biomass production, increased synthesis of proline, increased N uptake, and noticeable changes in ionic relations, based in a diminishing Na + , compared to non-mycorrhizal plants. Our results suggest that this improved ionic balance is due to a filtering effect of AMF structures both in the soil and in the root that prevents the entry of toxic Na + ions, which is important due to the level of lettuce production on saline soils improving the crop by means of directed inoculation with efficient AMF strains.

Efficiency of two arbuscular mycorrhizal fungal inocula to improve saline stress tolerance in lettuce plants by changes of antioxidant defense mechanisms

“…The AMF inoculations were: (1) non‐inoculated (NI) plants; (2) plants inoculated with a consortium containing indigenous ecotypes of AM fungi from Camiña valley (HMC); and (3) plants inoculated with the reference AMF strain Claroideoglomus claroideum (Cc). For each level of AM fungal inoculation, we used three irrigation saline levels: (i) non‐saline irrigation; (ii) plants irrigated with a 40 mmol L –1 NaCl solution; and (iii) plants irrigated with an 80 mmol L –1 NaCl solution, according to previous studies conducted under similar conditions . Two cultivars of lettuce were cropped crossed with the AMF and salinity treatments.…”

Arbuscular Mycorrhizal Fungi and K-Humate Combined as Biostimulants: Changes in Antioxidant Defense System and Radical Scavenging Capacity in Elaeagnus angustifolia

“…Furthermore, plant growth, photosynthesis, and nutrient uptake were also improved with AMF inoculation in another woody plant, Zelkova serrata, grown under salt stress (Wang et al 2019). Santander et al (2019) found that AMF inoculation improved ionic balance and prevented the entry of toxic Na + ions into the roots of lettuce under saline conditions. Further, the application of mycorrhizal fungi showed increased plant biomass and phosphorus concentration in turfgrass species under water stress conditions (Aalipour et al 2020).…”

Soil Biological Properties and Arbuscular Mycorrhizal Fungal Communities of Representative Crops Established in the Andean Region from Ecuadorian Highlands

“…agricultural ecosystems (Cornejo et al 2017;Anwar et al 2018). AMF are well known as helpful microorganisms which increase plant growth, water stress tolerance, and plant health (Santander et al 2017(Santander et al , 2019. Soil management practices affect not only soil properties and microbial responses but also AMF activities and their plant colonization ability (Cornejo et al 2009; Barea and Pozo 2013;Manoharan et al 2017).…”