Genetic diversity and symbiotic efficiency of pigeonpea rhizobia from the Brazilian drylands

Authors

  • Jonnathan Whiny Moraes dos Santos
  • Aldrin Martin Perez Marin
  • Paula Rose de Almeida Ribeiro
  • Ana Dolores Santiago de Freitas
  • Viviane Siqueira Lima Silva
  • Salete Alves de Moraes
  • Lindete Míria Vieira Martins
  • Paulo Ivan Fernandes Júnior

Abstract

The pigeonpea (Cajanus cajan) crop has a high potential for sustainable agricultural systems in semiarid regions due to its robustness, multifunctionality, and ability to perform biological nitrogen fixation in symbiosis with rhizobia. This study aimed to isolate and characterize native rhizobia at the molecular and symbiotic levels from pigeonpea root nodules cultivated in soils of the Brazilian drylands. A total of 19 bacterial isolates were obtained, 12 of which amplified the symbiotic nifH and nodC genes, which were subjected to Box-PCR fingerprinting and 16S rRNA gene sequencing. The isolates were classified into the Bradyrhizobium, Rhizobium, and Agrobacterium genera, with a notable genetic diversity observed even among samples from the same region. In a completely randomized greenhouse experiment under gnotobiotic conditions, 11 out of the 12 isolates exhibited symbiotic efficiency comparable to that of the commercial strain Bradyrhizobium pachyrhizi BR 2003 in at least one of the evaluated parameters (shoot dry biomass, number of nodules per plant, and N accumulation). The results indicate the presence of promising native rhizobia for use in inoculants adapted to the conditions of the Brazilian semiarid region, particularly the strains ESA 769, ESA 770, ESA 775, ESA 776, and ESA 777. Additionally, the presence of Agrobacterium strains capable of forming functional nodules in pigeonpea suggests the occurrence of horizontal gene transfer of symbiotic genes.

KEYWORDS: Cajanus cajan, Bradyrhizobium, Rhizobium, Agrobacterium, biological nitrogen fixation.

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Published

2025-10-13

How to Cite

SANTOS, Jonnathan Whiny Moraes dos; PEREZ MARIN, Aldrin Martin; RIBEIRO, Paula Rose de Almeida; FREITAS, Ana Dolores Santiago de; SILVA, Viviane Siqueira Lima; MORAES, Salete Alves de; MARTINS, Lindete Míria Vieira; FERNANDES JÚNIOR, Paulo Ivan. Genetic diversity and symbiotic efficiency of pigeonpea rhizobia from the Brazilian drylands. Pesquisa Agropecuária Tropical [Agricultural Research in the Tropics], Goiânia, p. e83256, 2025. Disponível em: https://revistas.ufg.br/pat/article/view/83256. Acesso em: 5 dec. 2025.

Issue

v. 55 (2025)

Section

Special Supplement: Pulses

License

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