Abstract
This work aimed to evaluate the symbiotic compatibility and nodulation efficiency of rhizobia isolated from Desmodium incanum, Lotus corniculatus, L. subbiflorus, L. uliginosus and L. glaber plants by cross-inoculation. Twelve reference strains and 21 native isolates of rhizobia were genetically analyzed by the BOX-PCR technique, which showed a high genetic diversity among the rhizobia studied. The isolates were also characterized based on their production of indolic compounds and siderophores, as well as on their tolerance to salinity. Fifteen of the 33 rhizobia analyzed were able to produce indolic compounds, whereas 13 produced siderophores. All the tested rhizobia were sensitive to high salinity, although some were able to grow in solutions of up to 2% NaCl. Most of the native rhizobia isolated from L. uliginosus were able to induce nodulation in all plant species studied. In a greenhouse experiment using both D. incanum and L. corniculatus plants, the rhizobia isolate UFRGS Lu2 promoted the greatest plant growth. The results demonstrate that there are native rhizobia in the soils of southern Brazil that have low host specificity and are able to induce nodulation and form active nodules in several plant species.
Highlights
In southern Brazil there are large areas dominated by grasslands
Lotus species present a high nutritional value as forage plants and, like Desmodium, they use the benefit of biological nitrogen fixation (BNF) through the symbiosis with bacteria belonging to rhizobia genera (Howieson et al, 2011)
Twenty-one native rhizobia were isolated from the root nodules of D. incanum or Lotus spp
Summary
In southern Brazil there are large areas dominated by grasslands These areas are a highly diverse forage resource, and most farms use this forage as a single food source for animals (Overbeck et al, 2007). Native leguminous plants, such as those belonging to the genus Desmodium, are frequently found in these areas (Overbeck et al, 2007) and, due to the symbiosis between these plants and rhizobial species, are responsible for an increase in the nitrogen content of the soil-plant system via the mechanism of biological nitrogen fixation (BNF) (Tarré et al, 2001). Lotus species present a high nutritional value as forage plants and, like Desmodium, they use the benefit of BNF through the symbiosis with bacteria belonging to rhizobia genera (Howieson et al, 2011)
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