Bacteria Nodulating Legumes - Legume Nodulation: A Global Perspective - page 71

4.2 -Proteobacteria

Table 4.6 lists the species of -Proteobacteria (collectively known as -rhizobia) cur-

rently known to nodulate and fix nitrogen in legumes. As with the -Proteobacteria

there is a strong relation between nodulating species and pathogens. Indeed, the first
species to be properly identified ( Cupriavidus taiwanensis , then called Ralstonia taiwanen-
sis ; Chen et al., 2001) was isolated not only from nodules but also from sputum of pa-
tients with cystic fibrosis. Burkholderia has species that are plant and animal pathogens
as well as legume symbionts, soil heterotrophs and strains that can fix nitrogen in asso-
ciation with grasses and other plants (Estrada de Los Santos et al., 2001). In addition to
the species in Table 4.6 there are numerous other reports of Burkholderia strains able to
nodulate legumes, and several of these are likely to be designated as new species in due
course - for example, strains isolated from a South African Rhynchosia species (Garau
et al., 2009). B. cepacia is a complex species with many pathogenic strains and which has
also been isolated from nodules (Rasolomampianina et al., 2005). This species has re-
cently been divided into five (Vanlaere et al., 2008). Burkholderias have also been found
to nodulate Lebeckia (J.G. Howieson, personal communication). Some species, like some

-rhizobia, can also fix nitrogen ex planta and growon the products (Elliott et al., 2007a).
The most detailed studies of the infection and development of nodules induced
by Burkholderia species are those on species of Mimosa and Cyclopia (Elliott et al.,
2007a, b). Both of these genera have a hair infection and form indeterminate nodules.
However, the results of Rasolomampian et al. (2005) with Dalbergia (crack infection, no
infection threads, determinate nodules) and Garau et al. (2008) with Rhynchosia (hair

Tab l e 4 . 6 -rhizobia. Several other species are likely to

be published soon (see text). B., Burkholderia ; C., Cupriavidus , M., Mimosa

Nodulation of legumes by defined species of

Species Origin of type strain Characteristics Reference

B. mimosarum M. pigra in Taiwan Highly competitive for Chen et al. (2006)

nodulation of invasive
Mimosa spp.

B. nodosa M. scabrella in Brazil Not yet found outside Chen et al. (2007)

Brazil

Machaerium lunatum 1 B. phymatum Broad host range in Moulin et al. (2001);

Mimosoideae. Fixes Vandamme et al.

N 2 ex planta (2002); Elliott et al.

(2007a)

B. sabiae M. caesalpinifolia No other hosts known Chen et al. (2008)

Aspalathus carnosa 1 B. tuberum Nodulates Cyclopia spp. Moulin et al. (2001);

but not several Vandamme et al.

Aspalathus spp. (2002); Elliott et al.

Fixes N 2 ex planta (2007b)

C. taiwanensis M. pudica in Taiwan Broad host range for Chen et al. (2001)

Mimosa spp. Elliott et al. (2007a)

1 Not authenticated on host of isolation, and in the case of Machaerium , roots possibly mistaken for those of a
Mimosa species.