Mycorrhiza-Induced Alterations in Metabolome of Medicago lupulina Leaves during Symbiosis Development

Abstract

The present study is aimed at disclosing metabolic profile alterations in the leaves of the Medicago lupulina MlS-1 line that result from high-efficiency arbuscular mycorrhiza (AM) symbiosis formed with Rhizophagus irregularis under condition of a low phosphorus level in the substrate. A highly effective AM symbiosis was established in the period from the stooling to the shoot branching initiation stage (the efficiency in stem height exceeded 200%). Mycorrhization led to a more intensive accumulation of phosphates (glycerophosphoglycerol and inorganic phosphate) in M. lupulina leaves. Metabolic spectra were detected with GS-MS analysis. The application of complex mathematical analyses made it possible to identify the clustering of various groups of 320 metabolites and thus demonstrate the central importance of the carbohydrate and carboxylate-amino acid clusters. The results obtained indicate a delay in the metabolic development of mycorrhized plants. Thus, AM not only accelerates the transition between plant developmental stages but delays biochemical “maturation” mainly in the form of a lag of sugar accumulation in comparison with non-mycorrhized plants. Several methods of statistical modeling proved that, at least with respect to determining the metabolic status of host-plant leaves, stages of phenological development have priority over calendar age.

The effect of inoculation with Rhizophagus irregularis on the expression level of phosphate transporter genes in the roots of Medicago lupulina under conditions of low phosphorus level in the substrate

“…The object of the study was a model system highly responsive to mycorrhization, including Medicago lupulina MLS-1 line and Rhizophagus irregularis highly effective strain RCAM00320. Plants were grown using a phytotron by standard microvegetative method [21,22]. Plants were grown in pairs in a vessel filled with 210 g soil-sand mixture with a low level of phosphorus (the content was calculated using the Kirsanov's reaction), which was 23 mg P205 per 1 kg of soil, pHKCl -6.4.…”

“…It should be assumed that the study of the effect of AM on the level of expression of genes-markers for the development of effective AM is the most relevant direction in both fundamental and applied research on symbiotic interactions. To solve this problem, our team previously developed a new model system "Rhizophagus irregularis + Medicago lupulina", which includes a highly effective strain of AM fungus and M. lupulina line that is characterized by high response to mycorrhization [21]. The aim of this study was to analyze the effect of inoculation with Rhizophagus irregularis effective laboratory strain RCAM00320 on the level of expression of the genes of the phosphate transporters (MlPT1, MlPT2, MlPT4) and H+-dependent ATPase, MlATP1 (where "Ml" is the abbreviation of the M. lupulina species) in the roots of a new model plant, a highly efficient M. lupulina MlS-1 line, which is characterized by high response to mycorrhization under conditions of low phosphorus levels in the substrate.…”

Plant Heterotrophic Cultures: No Food, No Growth

“…In addition, plants are able to use proteins as specialized reserves of nitrogen and carbon accumulated into protein storage vacuoles [ 165 , 166 ]. Free amino acids are widely represented in the profiles of cell culture metabolites, and some of them are in relatively high concentration [ 157 , 158 , 167 ]. These metabolites are an important component of phloem sap, and in some cases their total concentration can be comparable to that of sucrose [ 114 , 123 , 168 , 169 ].…”

The Effects of Rhizophagus irregularis Inoculation on Transcriptome of Medicago lupulina Leaves at Early Vegetative and Flowering Stages of Plant Development

“…AM fungi strongly depend on the photosynthesis products of the host plant; therefore, they have a great impact on this process [56]. We have previously shown that R. irregularis significantly increases both the content of chlorophyll a and b, and leads to a considerable increase in leaf area during the second leaf development stage, 24 DAS [49]. The importance of carbohydrate metabolism is confirmed by the results, which showed high photosynthesis activity in the presence of AM according to the assessment of the effective photochemical quantum yield of photosystem II-Y(II) at an early stage of development, with a sequential decrease at the flowering stage [49].…”

“…The transcriptomic analysis of the model PMS "Medicago lupulina + Rhizophagus irregularis", with MGR > 350% under conditions of phosphorus (P) deficiency for plant nutrition is promising [46]. The micro-vegetative experiments in M. lupulina provided in our earlier experiments during the development of AM symbiosis showed significant changes in the course of development and hormonal rearrangements in the host plant [47,48]; metabolic rearrangements [30,49]; and changes in the expression of a number of genes for carbohydrate metabolism and P transport [50].…”