Arbuscular mycorrhizal fungi (AMF, Glomeromycota) establish beneficial associations with the roots of most land plants, including important food crops, from cereals to legumes, vegetables and fruit trees, and contribute to key agroecosystem processes, such as nutrient uptake, soil aggregation and carbon sequestration. In addition, AMF protect plants from soilborne fungal pathogens and abiotic stresses, such as drought and salinity. AMF performance is affected by the diverse bacterial communities strictly associated with their spores, which differentially enhance the availability of nutrients, such as P, N, S, K, Ca, Cu and Zn. In our work we utilized: i) a culture-independent approach, PCR-DGGE, to identify the diverse bacterial species associated with Rhizoglomus intraradices IMA6 spores; ii) a culture-dependent approach to isolate such bacteria and detect their functionally important traits. Sequence analysis of the major DGGE bands showed the occurrence of Arthrobacter, Bacillus, Herbaspirillum, Massilia, Pseudomonas, Rhizobium, Streptomyces genera, possibly playing functional roles in the enhancement of nutrient availability to fungal mycelium and plant roots, in plant pathogens control and in plant growth promotion. Isolation in pure culture of the microbiota associated with R. intraradices spores showed the occurrence of 374 strains, which were functionally characterized for P-solubilizing, chitinase, nitrogen fixing activity and production of siderophores and indole acetic acid (IAA). Phosphatase and phytase activities were detected in 73% and 100% of Actinobacteria, in 74% and 83% of chitinolytic bacteria and in 44% and 52% of nitrogen-fixers. Variable combinations of such bacteria may be at the basis of the differential performance of AMF isolates, in terms of infectivity and efficiency. The isolation of bacteria strictly associated with AMF spores and the investigation of their functional significance represent an essential step, in order to select the best AMF/bacteria combinations to be used as biofertilisers and bioenhancers in sustainable agroecosystems.
Multitrophic interactions in the sporosphere of the plant beneficial symbiont Rhizoglomus intraradices
AGNOLUCCI, MONICA;BATTINI, FABIO;CRISTANI, CATERINA;GIOVANNETTI, MANUELA
2015-01-01
Abstract
Arbuscular mycorrhizal fungi (AMF, Glomeromycota) establish beneficial associations with the roots of most land plants, including important food crops, from cereals to legumes, vegetables and fruit trees, and contribute to key agroecosystem processes, such as nutrient uptake, soil aggregation and carbon sequestration. In addition, AMF protect plants from soilborne fungal pathogens and abiotic stresses, such as drought and salinity. AMF performance is affected by the diverse bacterial communities strictly associated with their spores, which differentially enhance the availability of nutrients, such as P, N, S, K, Ca, Cu and Zn. In our work we utilized: i) a culture-independent approach, PCR-DGGE, to identify the diverse bacterial species associated with Rhizoglomus intraradices IMA6 spores; ii) a culture-dependent approach to isolate such bacteria and detect their functionally important traits. Sequence analysis of the major DGGE bands showed the occurrence of Arthrobacter, Bacillus, Herbaspirillum, Massilia, Pseudomonas, Rhizobium, Streptomyces genera, possibly playing functional roles in the enhancement of nutrient availability to fungal mycelium and plant roots, in plant pathogens control and in plant growth promotion. Isolation in pure culture of the microbiota associated with R. intraradices spores showed the occurrence of 374 strains, which were functionally characterized for P-solubilizing, chitinase, nitrogen fixing activity and production of siderophores and indole acetic acid (IAA). Phosphatase and phytase activities were detected in 73% and 100% of Actinobacteria, in 74% and 83% of chitinolytic bacteria and in 44% and 52% of nitrogen-fixers. Variable combinations of such bacteria may be at the basis of the differential performance of AMF isolates, in terms of infectivity and efficiency. The isolation of bacteria strictly associated with AMF spores and the investigation of their functional significance represent an essential step, in order to select the best AMF/bacteria combinations to be used as biofertilisers and bioenhancers in sustainable agroecosystems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
