Agriculture Reference
In-Depth Information
to humans causing localized or disseminated infections (O'Donnell et al.
2004
).
The aims and objectives of comparative genomes project has been to make genome
sequence data for strains available along with the host specificities. The first among
strains of
F. oxysporum
spp was made available in 2007 which caused tomato wilt
and on comparison with
F. graminearum
and
F. verticillioides
genomes, and it
was discovered that the mobile supernumerary chromosomes contained genes for
host specific infection and disease (Ma et al.
2010
). Subsequently, 11 more strains
of
F. oxysporum
have been sequenced out of which two infected tomato (Gale et al.
2003
; Rosewich et al.
1999
). The other two of the sequenced strains showed speci-
ficity towards crucifers (cabbage yellow disease, radish wilt),
Arabidopsis
(Diener
and Ausubel
2005
) and the other sequenced strain caused wilt of banana, melon,
cotton and pea (Fourie et al.
2011
). Some
Fusarium oxysporum
strains causing
humans diseases such as strains from human blood (O'Donnell et al.
2004
) have
been shown to cause necrotic diseases in immune-competent individuals such as
outbreak of keratitis in contact lens users (Chang et al.
2006
) and may also be
disseminating infections in neutropenic patients (Boutati and Anaissie
1997
). Fur-
thermore, a strain of
Fusarium oxysporum
has been sequenced which is known to
colonize host roots and shown to be biotic component for wilt disease suppression
(Fravel et al.
2003
). Another important species among
Fusarium
which is distrib-
uted worldwide is
Fusarium graminearum
which causes head blight of wheat and
barley (O'Donnell et al.
2000
,
2004
) and it had an economic losses worth of ap-
proximately 3 billion dollars in 1990s to U.S. agriculture (McMullen et al.
1997
;
Windels
2000
), further it is becoming a threat due to outbreaks in Canada, Europe,
Asia and South America in recent past (Dubin et al.
1997
).
Fusarium graminearum
species also causes disease on rice and corn (White
1999
; Webster and Gunnell
1992
) and results in reduced yield and seed quality and also the infestation makes
the food and feed unsuitable due to production of mycotoxins (McMullen et al.
1997
). The strains of
Fusarium graminearum
sequenced by International Gibber-
ella zeae Genomics Consortium (IGGR) was PH-1 (NRRL 31084) (Trail and Com-
mon
2000
) was shown to produce mycotoxins; trichothecenes and zearalenone such
as deoxynivalenol and nivalenol toxin (Garvey et al.
2008
). Another important spe-
cies present worldwide is
Fusarium verticillioides
causes kernel and ear rot disease
of maize. The abiotic stress conditions such as high temperature, drought along with
other biotic factors such as the damage by insect can further amplify and enhance
the disease and thus cause reduce crop quality and yield. The negative economic
impact of this species causing several animal (Howard et al.
2001
; Seefelder et al.
2003
; Wilson et al.
1992
; Kriek et al.
1981
) and human diseases (Seefelder et al.
2003
) is due to fumonisin mycotoxins.
Plant-Defense Responses
The evolution of fungi is dependent directly on the development and the spread of
green plants and most of fungi are saprophytic and few among them are parasitic.
These fungi require nutrients to complete their life cycle, which is provided to them
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