TABLE 1.

Functional classes and likely orthologues in other rhizobia of symbiosis island genes

Functional classNo. of genes in R7A islandNo. of genesa also in:
MAFF303099 symbiotic islandS. meliloti 1021 genomebpNGR234aB. japonicum symbiotic cluster
Nodulation16168a, 1b1510
N fixation202016a2020
Regulatory function27212a, 6b, 6c82
Small molecule metabolism957813a, 14b, 14c209
Macromolecule metabolism1382a, 1b12
Cell processes51315a, 5b, 9c141
Elements of external origin18105a, 2b68
Structural elements321c11
Hypothetical
    Globalc37313a, 4b, 2c144
    Partial257
    No matches10913
    Total414237119 (54a, 33b, 32c)9957
  • a Likely orthologues were defined as sharing at least 40% amino acid identity over at least 80% of both subject and query sequences.

  • b a, b, and c represent S. meliloti pSyma, pSymb, and chromosome respectively.

  • c Defined as sharing similarity over at least 80% of both subject and query sequences and an “Expect” value of less than 1e−6.