Agriculture Reference
In-Depth Information
4.1.6
Methylobacterium
M. nodulans
was first described from nodules of species of
Crotalaria
(Sy et al., 2001).
One of its characteristics was the ability to metabolise methanol, but another species,
not yet fully characterised, nodulating some
Lotononis
species, does not (Yates et al.,
2007). Renier et al. (2008) examined in more detail the interactions between
M. nodulans
ORS2060 and
C. podocarpa
. They found that these two symbionts interacted in a gener-
ally similar way to other host/rhizobia pairs, with difference in detail, such as structure
of Nod factors. They further suggested, as for
Azorhizobium
(above) and
Phyllobacterium
(see Section 4.1.9), that
nod
genes have been acquired by lateral transfer from other, as
yet unidentified rhizobia.
4.1.7
Ochrobactrum
The genus
Ochrobactrum
is classified in family Brucellaceae, which also includes the
important animal and human pathogenic genus
Brucella
. There are interesting simi-
larities between these pathogens and nodulating bacteria, which have been discussed
elsewhere (Batut et al., 2004; Soto et al., 2006).
There are now three reports that species of
Ochrobactrum
nodulate legumes. The first
was fromNgom et al. (2004), who isolated an as-yet-unnamed species from nodules of
Acacia mangium
grown in the Philippines and Thailand. This strain was able to form
effective nodules on
A. mangium
,
Faidherbia albida
(cited as
A. albida
)and
Falcataria
moluccana
(cited as
Paraserianthes falcataria
), all mimosoid legumes. The second report
was of
O. lupini
,isolatedfrom
Lupinus honoratus
in Argentina and able to nodulate
L. albus
(Trujillo et al., 2005). The nodules were formed in the axils of lateral roots,
rather than along the root as is usual for lupin (Chapters 1 and 3), but, on the basis of
plant weight, were found to be effective. No structural details were given. The third
report was of
O. cytisi
, isolated from nodules of
Cytisus scoparius
in Spain and found
to form ineffective nodules on
Phaseolus vulgaris
, but not tested on its host of isolation
(Zurdo-Pi neiro et al., 2007). Thus we have an interesting but frustrating situation in
which two or three species of
Ochrobactrum
, isolated from three continents, appear
to be able to nodulate mimosoid and papilionoid legumes via root hairs, forming
indeterminate (mimosoid species) and determinate (
P. vulgaris
) nodules as well as
non-hair-infected nodules (lupins and possibly
Cytisus
).
4.1.8
Mesorhizobium
Classified in the Phyllobacteriaceae,
Mesorhizobium
is a genus nodulating awide variety
of legumes, including several mimosoid genera and a caesalpiniod one (
Chamaecrista
).
It is worth noting that the latter genus can also be nodulated by the widely used
inoculant strain CB756, a member of the cowpea miscellany in the bradyrhizobia.
Table 4.5 lists the currently described species. Note that there are three additions to
the references cited in Graham (2008) - the topic containing this chapter had rather a
long gestation time! There are likely to be further additions shortly, since, for example,
Donate-Correa et al. (2007) isolated a range of mesorhizobia from
Anagyris latifolia
in
the Canary Islands and thought some of these would be identified as new species.
