The effects of soil phosphorus and zinc availability on plant responses to mycorrhizal fungi: a physiological and molecular assessment

Abstract

The positive effects of arbuscular mycorrhizal fungi (AMF) have been demonstrated for plant biomass, and zinc (Zn) and phosphorus (P) uptake, under soil nutrient deficiency. Additionally, a number of Zn and P transporter genes are affected by mycorrhizal colonisation or implicated in the mycorrhizal pathway of uptake. However, a comprehensive study of plant physiology and gene expression simultaneously, remains to be undertaken. Medicago truncatula was grown at different soil P and Zn availabilities, with or without inoculation of Rhizophagus irregularis. Measures of biomass, shoot elemental concentrations, mycorrhizal colonisation, and expression of Zn transporter (ZIP) and phosphate transporter (PT) genes in the roots, were taken. Mycorrhizal plants had a greater tolerance of both P and Zn soil deficiency; there was also evidence of AMF protecting plants against excessive Zn accumulation at high soil Zn. The expression of all PT genes was interactive with both P availability and mycorrhizal colonisation. MtZIP5 expression was induced both by AMF and soil Zn deficiency, while MtZIP2 was down-regulated in mycorrhizal plants, and up-regulated with increasing soil Zn concentration. These findings provide the first comprehensive physiological and molecular picture of plant-mycorrhizal fungal symbiosis with regard to soil P and Zn availability. Mycorrhizal fungi conferred tolerance to soil Zn and P deficiency and this could be linked to the induction of the ZIP transporter gene MtZIP5, and the PT gene MtPT4.

Optimization of Zinc Application Rates With and Without Arbuscular Mycorrhizal Fungi for the Improvement in Maize Growth, Gas Exchange Attributes and Yield in Zinc Deficient Soil

“…Inoculation of AMF, improved total soluble protein contents in maize [51,52]. Results of our study are in accordance with Nguyen et al [52]. In soil with low Zn, AMF increases carbonic anhydrase enzyme activity and enhances photosynthesis.…”

“…Vassilev et al (2011) studied that excess Zn in plant tissues, reduced Mg 2+ uptake and replace Mg atom, which distorts chlorophyll structure and result in decreased photosynthetic rate [49]. Inoculation of AMF, improved total soluble protein contents in maize [51,52]. Results of our study are in accordance with Nguyen et al [52].…”

“…In soil with low Zn, AMF increases carbonic anhydrase enzyme activity and enhances photosynthesis. In contrast, soil with high Zn, AMF imparted protective effect on plants by mitigating its toxicity effect [52]. In this study, results showed that AMF inoculated plants showed a better physiological response at high soil Zn as compared to mock-inoculated and results are in line with Wang et al [16].…”

Mycorrhizae can support squash plant growth in Phosphorus deficient calcareous soil

“…In contrast, at low level of P supply, there was a highly significant difference between squash plants treated with all mycorrhizal strains especially mycorrhizal strain (M301) as compared with other squash plants without mycorrhizal inoculation. This result was in the same line with Nguyen et al (2019) who demonstrated that mycorrhizal fungi gave plants tolerance to P deficiency and this may be due to the motivation of the phosphate transporter (PT) genes (MtPT4) in the roots.…”

Arbuscular Mycorrhizal Symbiosis Mitigates Iron (Fe)-Deficiency Retardation in Alfalfa (Medicago sativa L.) Through the Enhancement of Fe Accumulation and Sulfur-Assisted Antioxidant Defense

“…These elemental improvements may also assist alfalfa plants in coping with Fe deficiency. AMF is known to enhance Zn [41] and P [42] in Medicago trunculata. Taken together, AMF-mediated alleviation of Fe deficiency not only associated with the restoration of Fe status but also improve the increase of vital elements, such as Zn, Ca, and P in alfalfa.…”