The Interaction of Arbuscular Mycorrhizal Fungi and Phosphorus Inputs on Selenium Uptake by Alfalfa (Medicago sativa L.) and Selenium Fraction Transformation in Soil

Abstract

Selenium (Se) is a beneficial element to plants and an essential element to humans. Colonization by arbuscular mycorrhizal fungi (AMF) and supply of phosphorus (P) fertilizer may affect the bioavailability of Se in soils and the absorption of Se by plants. To investigate the interaction between AMF and P fertilizer on the transformation of soil Se fractions and the availability of Se in the rhizosphere of alfalfa, we conducted a pot experiment to grow alfalfa in a loessial soil with three P levels (0, 5, and 20 mg kg-1) and two mycorrhizal inoculation treatments (without mycorrhizal inoculation [−AMF] and with mycorrhizal inoculation [+AMF]), and the interaction between the two factors was estimated with two-way ANOVA. The soil in all pots was supplied with Se (Na 2 SeO 3) at 1 mg kg-1. In our results, shoot Se concentration decreased, but plant Se content increased significantly as P level increased and had a significant positive correlation with AMF colonization rate. The amount of total carboxylates in the rhizosphere was strongly affected by AMF. The amounts of rhizosphere carboxylates and alkaline phosphatase activity in the +AMF and 0P treatments were significantly higher than those in other treatments. The concentration of exchangeable-Se in rhizosphere soil had a positive correlation with carboxylates. We speculated that rhizosphere carboxylates promoted the transformation of stable Se (iron oxide-bound Se) into available Se forms, i.e. exchangeable Se and soluble Se. Colonization by AMF and low P availability stimulated alfalfa roots to release more carboxylates and alkaline phosphatase. AMF and P fertilizer affected the transformation of soil Se fractions in the rhizosphere of alfalfa.

Phosphorus-Use Efficiency Modified by Complementary Effects of P Supply Intensity With Limited Root Growth Space

“…As P is immobilized, increasing mineral P input into the soil is a common agronomy practice used to improve productivity (Zhang et al, 2019 ). In the present study, both bulk and rhizosphere soil Olsen-P concentrations increased as P supply increased ( Figure 5 ; Supplementary Figure 5 ), which is similar to the findings observed when alfalfa was grown in a loessial soil (Peng et al, 2020 ). P is a nutrient that stimulates shoot biomass production and more importantly, acts as a regulatory signal mediating changes in root architecture (López-Bucio et al, 2003 ; Pongrac et al, 2020 ).…”

AMF colonization affects allelopathic effects of Zea mays L. root exudates and community structure of rhizosphere bacteria

“…Soil enzyme vigor is closely related to the function of the soil ecosystem and can reflect the metabolic capacity of soil microorganisms ( Zarea et al., 2011 ; Bowles et al., 2014 ), and microbial changes can directly affect the activity of soil enzymes ( Pereira et al., 2016 ). Some studies have shown that AMF can improve the host’s absorption of mineral elements by affecting the soil enzyme vigor ( Peng et al., 2020 ), and AMF can improve the activity of N-related enzymes in the host’s rhizosphere soil at the early stage of colonization to promote the host’s absorption of nitrogen ( Stamou et al., 2017 ). There is also a certain correlation between the change of soil enzyme vigor and the change of root exudates.…”

Illumina MiSeq Sequencing Reveals Correlations among Fruit Ingredients, Environmental Factors, and AMF Communities in Three Lycium Barbarum Producing Regions of China

“…Even under low phosphorus conditions in the Zhongning region, effective phosphorus concentration increased significantly after a few months, especially in the high-demand month of July. Perhaps, under low phosphorus availability, AMF colonization stimulated plant roots to release additional carboxylates and alkaline phosphatase ( 70 ). Overall, understanding the effects of various environmental factors on AMF communities can provide better insights into host plant growth and better crop yields.…”