Diversity and symbiotic effectiveness of rhizobia isolated from field-grown soybean nodules in Paraguay

Chen, Lu; Figueredo, Antonio; Villani, Hugo; Michajluk, Javier; Hungría, Mariangela

doi:10.1007/s00374-002-0493-1

Cited by 65 publications

(44 citation statements)

References 24 publications

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“…van Rossum et al, 1995;Moreira, 1991Moreira, , 2000Moreira et al, 1993;Boddey & Hungria, 1997; Doignon-Bourcier et al, 1999;Chen et al, 2002). However, the diversity observed among bradyrhizobial strains is usually not reflected in 16S rRNA gene sequence analysis; therefore, few Bradyrhizobium species have been described so far.…”

Section: Discussionmentioning

confidence: 99%

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Germano

Menna

Mostasso

et al. 2006

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLO

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Genetic diversity in tropical rhizobial species is still poorly known. With the aim of increasing this knowledge, three ribosomal regions of 119 strains belonging to the official Brazilian culture collection of rhizobia and classified as Bradyrhizobium based on morphological and physiological characteristics in vitro were analysed by RFLP-PCR. The strains were isolated from 33 legume species, representing nine tribes and all three subfamilies; they all form very effective N 2 -fixing nodules and 43 of them are recommended for use in Brazilian commercial inoculants as the most effective for their hosts. For the 16S rRNA gene, type and reference strains of Bradyrhizobium japonicum fell into two major clusters, joined at a level of similarity of 50 %, which included 52 strains, 90 % of which were isolated from soybean. Two other clusters, joined at a similarity of 53 %, included reference strains of Bradyrhizobium elkanii, but not USDA 76 T ; furthermore, two other major clusters were identified and all strains were clustered at a final level of similarity of only 28 %. For the intergenic spacer (IGS) between genes coding for the 16S and 23S rRNA, strains were clustered at a final level of similarity of 27 %. Reference strains of B. japonicum fell into a major group with 51 strains, 84 % isolated from soybean, with a similarity of 59 %, while strains of B. elkanii fell into another major group, with a similarity of 55 %, clustering 44 strains, 59 % of which were isolated from hosts other than soybean. New clusters were also observed for the IGS region. The largest number of differences was detected in the analysis of the 23S rRNA gene, and 16 groups and isolated strains were joined at a very low level of similarity (16 %). In a combined analysis with the three ribosomal regions, the majority of strains isolated from soybean clustered with a similarity of 54 % with type and reference strains of B. japonicum, while most strains isolated from Brazilian indigenous legume species grouped with B. elkanii at a level of similarity of 46 %. All strains were clustered at a very low level of similarity (27 %), and at least two new clusters were clearly defined. These new clusters might be related to intraspecific differences or to novel subspecies, or even to novel species; indeed, strains from one of these clusters show higher 16S rRNA gene sequence similarity to members of the genus Burkholderia. The results obtained in this study emphasize the high level of diversity of symbiotic diazotrophic bacteria in the tropics that still remains to be determined. INTRODUCTIONThe Leguminosae (known as the Fabaceae in the USA) is one of the largest families of plants, with over 18 000 species classified into around 650 genera, representing approximately one-twelfth of all known flowering plants and occupying nearly all terrestrial biomes (Polhill & Raven, 1981). Many species within this family are capable of establishing symbioses with a group of bacteria collectively called rhizobia, of which the most important feature is the capacity...

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Section: Discussionmentioning

confidence: 99%

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Germano

Menna

Mostasso

et al. 2006

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLO

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“…Phytohormone production, particularly of indoleacetic acid (IAA), by rhizobia has been identified as one of the mechanisms promoting growth in non-leguminous plants (Yanni et al 2001; Chi et al 2005) in terms of root growth, root hair proliferation, and the improvement of soil water and nutrient absorption by infected plants (Fuentes-Ramírez & Caballero-Mellado 2005). IAA production by rhizobia, ranging from 1.0 to 130.3 mg IAA.mL -1 , was also observed in isolates of soybean rhizobia (Chen et al 2002). …”

Section: Discussionmentioning

confidence: 78%

Rooting and acclimatization of micropropagated marubakaido apple rootstock using Adesmia latifolia rhizobia

Muniz

Dalagnol

et al. 2013

SpringerPlus

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In vitro rooting and the acclimatization of micropropagated rootstocks of apple trees is essential for plant development in the field. The aim of this work was to assess the use of rhizobia of Adesmia latifolia to promote rooting and acclimatization in micropropagated Marubakaido apple rootstock. An experiment involving in vitro rooting and acclimatization was performed with four strains of rhizobium and two controls, one with and the other without the addition of synthetic indoleacetic acid. The inoculated treatments involved the use of sterile inoculum and inoculum containing live rhizobia. The most significant effects on the rooting rate, primary-root length, number of roots, root length, fresh-shoot biomass, and fresh-root biomass were obtained by inoculation with strain EEL16010B and with synthetic indole acetic acid. However, there was no difference in the growth of apple explants in the acclimatization experiments. Strain EEL16010B can be used to induce in vitro rooting of the Marubakaido rootstock and can replace the use of synthetic indoleacetic acid in the rooting of this cultivar.

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“…Despite the less-than-ideal situation, nodulation occurs without inoculation in most areas of Alto Paraná and Itapúa, where 80% of soybean production occurs (Figueredo, 1998). Symbiotic effectiveness varies from site to site but, in a recent survey, some isolates collected in the field were outstanding symbiotic performers, a first step for the identification of strains for use in commercial local inoculants (Chen et al, 2002). is considered, the fixed-N requirement would be slightly more than 220 kg ha -1 .…”

Section: Biological Nitrogen Fixationmentioning

confidence: 99%

The Importance of Nitrogen Fixation to Soybean Cropping in South America

Hungría

Franchini

Campo

et al.

Nitrogen Fixation: Origins, Applications, and Research Progress

102

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Diversity and symbiotic effectiveness of rhizobia isolated from field-grown soybean nodules in Paraguay

Cited by 65 publications

References 24 publications

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Rooting and acclimatization of micropropagated marubakaido apple rootstock using Adesmia latifolia rhizobia

The Importance of Nitrogen Fixation to Soybean Cropping in South America

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