“PLANT-SOIL INTERACTIONS” – Scientific Achievements – Research Group 3

Research Group

Microorganism-plant symbiotic interactions. Influence of various environmental stress factors in separate and combined inoculation with microorganisms on productivity and quality of yield in plants

The recent studies focused on the evaluation of the responses of pot marigold (Calendula officinalis L.), marjoram (Origanum majorana L.), and goldenberry (Physalis peruviana L.) grown on industrially polluted with Cd and Pb soils to four arbuscular mycorrhizal fungi strains. Two isolates from soil naturally enriched with heavy metals (Claroideoglomus claroideum EEZ 54 and Funneliformis mosseae EEZ 55) and two isolates from industrially metal-contaminated sites (Claroideoglomus claroideum – ЕЕЗ 35 and Rhizophagus clarum EEZ-37) were used. We investigated the effects of the bio-communication between arbuscular mycorrhizal fungi Claroideoglomus claroideum EEZ 54 and microalgae Scenedesmus incrassatulus R 83 and Synechocystis sp. R 10 on parameters connected with mycorrhization, plant development, bioactive component content and antioxidant defense system of basil (Ocimum basilicum L.).The results showed that the investigated plants are tolerant to heavy metal contamination, but arbuscular mycorrhizal fungi benefit plant development and soil remediation:

  • Higher stability and activity in mycorrhizal fungi isolated from soils naturally enriched with heavy metals was established as compared with the strains isolated from artificially contaminated soil which showed lower activity.
  • Arbuscular mycorrhizal fungi lead to the improved growth of the studied medicinal plants and maintain concentrations of heavy metals in medicinal plants below critical values.
  • Determination of appropriate and productive strains for marigold, marjoram and physalis inoculation lead to produce plant products – minimal treated with synthetic fertilizers and clean the content of potentially harmful ingredients.
  • The development of algae in the soil promotes more rapid germination, growth and accumulation of pigments in leaves of 1-month-old plants while at a later stage (4-month-old plants) more pronounced is the stimulus of AMF. Only with regard to AMF colonization in both young plants and in the aged plants microalgae reduce the development of mycorrhizal hyphae.

The mycorrhizal status was best manifested in the plant roots inoculated with Claroideoglomus claroideum – EEZ 54 (from naturally enriched metal-contaminated sites) which was in correspondence with the values of root acid phosphatase activity and accumulation of total phenols and flavonoids. Neither Pb nor Cd was detected in the inoculated marigold and marjoram flowers (flos drug). The tested AMF promoted the accumulation in medicinal plants of important secondary metabolites (total phenols, flavonoids, carotenoids, water and lipid soluble antioxidants) and, therefore, increased the antioxidant capacity.

The carotenoid profile of pot marigold mycorrhizal plants showed significant differences between the main defined constituents (lutein, lycopene, β-carotene). The highest values of β-carotene (respectively vitamin A) and lycopene were found in pot marigold- EEZ-55 association.

The highest value of the total identified essential oils compounds like sabinene and its isomers, linalyl acetate and limonene, isolated from marjoram shoots was observed in plants inoculated with EEZ 35, where Pb accumulated in the roots.

As a result, of inoculation with both EEZ-54 and EEZ-37 strains the considerable reduction of Cd in the golden berry fruits was observed, compared to nonmycorrhizal plants. The fruit number and root and shoot dry weights increased in plants associated with C. claroideum. Mycorrhizal establishment changed the composition and concentration of fatty acids of golden berry fruits, resulting in an increased ratio of unsaturated fatty acids.

Fatty acids profile (as a percentage of total fatty acid methyl esters (FAME)), total lipids (%) and total carotenoids (mg g DW-1) in the fruits of P. Peruviana, inoculated with two AMF strains (EEZ 37, EEZ 54).

Fatty acid (%) NM EEZ-37 EEZ-54
16:0 (Palmitic) 13.1±0.6 13.7±0.7 13.7±0.7
16:1(Palmitoleic) 1.1±0.1 0.7±0.03 1.3±0.07
18:0 (Stearic) 0.2±0.01 0.6±0.02 0.5±0.03
18:1(Oleic) 10.8±0.6 12.0±0.5 11.7±0.6
18:2 (Linoleic) 74.5±3.8 71.1±3.6 72.6±3.4
α-18:3 (Linolenic) 0.2±0.01 1.9±0.1 0.3±0.01
Lipids (%) 9.5 7.8 8.7
Total carotenoids (mg g DW-1) 0.63±0.023 0.70±0.03 0.67±0.020

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