Agriculture Reference
In-Depth Information
son and Persson
1994
). This mycoparasitic behaviour of
A.
oligospora
showed the
biocontrol capability of nematode-trapping fungi as biocontrol agents to nematodes
as well as fungal parasites. Many other nematode-trapping fungi, including
A. oli-
gospora,
A. superba,
A. conoides
,
Monacrosporium globosporum
and
M. sinense
actively colonize the sclerotia of
Sclerotinia sclerotiorum
in natural soils (Li et al.
2001). This group also identified a new fungal species
Monacrosporium janus
sp.
nov. parasitizing sclerotia and hyphae of
Sclerotinia sclerotiorum
along with
R.
solani
,
Fusarium solani
f.sp.
pisi
and
Phytophthora cactorum
. More investigation
of this kind of characteristic of nematode-trapping fungi may result in discovering
more effective strains for control of both soil-borne plant pathogenic fungi and phy-
tonematodes in a single application.
3.2 Root Endophytes
The term endophyte was always closely associated with beneficial organisms colo-
nizing the phyllospore. However, the definition of an endophyte is now broadened
and now includes any organisms that live in plant tissues whether neutral, beneficial
or detrimental (Sikora et al. 2007). Nematode-trapping fungi also have the abil-
ity to infect and colonize plant roots (Jansson and Lopez Llorca
2004
). From the
biological control point of view, the presence of nematode-trapping fungi in the
rhizosphere of agricultural plants shows their potential bicontrol ability. Persmark
and Jansson (
1997
) noticed maximum number of nematode-trapping fungi from the
pea rhizosphere with maximum frequency of
A. oligospora
. Bordallo et al. (
2002
)
compared
A. oligospora
with an egg parasitic fungus
Pochania
chlamydospora
in
the rhizosphere of barley and tomato and observed that both the fungi formed ap-
pressoria during penetration of plant cell walls and colonized epidermis and cortex.
They suggested that colonization of plant roots and formation of appresoria by these
fungi as root endophytes, may render the plants more resistant to plant parasitic
nematodes and have profound implication for their suitability as biocontrol agents
of plant parasitic nematodes. Our observation also showed that the colonized root
of plants with
A. oligospora
when placed in agar plates, the juveniles released from
the egg masses present on root knot captured on its release (Fig.
12.1h
) which might
also occur in the soil during disintegration of infected roots.
4 Improvement of Nematode-Trapping Fungi
by Genetic Engineering
There is an important arena of basic and applied research opportunities in the ge-
netic tailoring of organisms for effectiveness in specific environmental and cul-
tural situations. Advances in the techniques of biotechnology introduce additional
