Biology Reference
In-Depth Information
(Van Egmond 2004). As an example, the EU
regulation allows a maximum deoxynivalenol
(DON) content in unprocessed bread wheat of
1.25 ppm, in bread and bakeries of 0.5 ppm, and
in baby food of 0.2 ppm (Anonymous 2005).
In the past two decades, several review arti-
cles have been published on Fusarium diseases
of cereals covering different aspects. Parry et al.
(1995) reviewed the significance of the dis-
ease with an emphasis on phytopathological
aspects. Goswami and Kistler (2005) provided
a comprehensive survey of
Fusarium gramin-
earum
. Reviews of conventional breeding for
FHB resistance were published by Mesterhazy
(1995), Miedaner (1997), and Mesterhazy et al.
(1999). Placinta et al. (1999) documented the
worldwide occurrence and significance of Fusar-
ium mycotoxins. The first review on molecu-
lar markers for FHB resistance in wheat by
Kolb et al. (2001) summarized the early find-
ings in this field, and later Anderson (2007)
listed some of the more stable FHB QTL and
reviewed the advantages of marker-assisted FHB
resistance breeding. A comprehensive mono-
graph edited by Leonard and Bushnell (2003)
described a range of aspects of Fusarium diseases
of small-grain cereals, including the pathogen,
the associated mycotoxins, resistance breeding,
and other control options, as well as the social
and economic impact of the disease. Bai and
Shaner (2004) reviewed the management and
resistance to FHB in wheat and barley, includ-
ing the knowledge on FHB resistance QTL
mainly from a North American perspective.
Buerstmayr et al. (2012) provided an updated
survey of Fusarium resistance breeding by
conventional, genomics-assisted, and transgenic
approaches.
The disease occurs regularly in many wheat-
growing regions with moderate to low sever-
ity, depending on weather conditions and agri-
cultural practices. Heavy epidemics with severe
yield and quality losses have been reported quite
a few times from various regions of the world.
As an example, heavy epidemics of FHB have
been reported in North America in 1919, 1928,
1932, and 1935 (Stack 2003). An extraordinary
series of FHB epidemics struck different areas
of North America during the 1990s, resulting
in about $1.3 billion of total direct losses and
$4.8 billion of losses for the accumulative eco-
nomic impact of FHB (Johnson er al. 2003). In
parts of China, such as the Yangtze valley, severe
FHB epidemics have been reported 4 times and
moderate epidemics 15 times during the 1957-
1984 period (Liu 1985). Even in cases when
disease severity is moderate to low and visual
symptoms appear at modest incidence, the crop
can be contaminated with Fusarium toxins way
above the tolerable level.
The Fusarium species involved in FHB live
a saprophytic life for the most part of the year.
Fusarium is an opportunistic pathogen. Specifi-
cally, at anthesis the cereal head becomes vulner-
able to Fusarium infection. Airborne or splash-
dispersed spores germinate at the glumes and
fungal hyphae enter through the open floret and
infect living ear tissue. In order to reduce the
damage due to Fusarium head blight integrated
control measures are needed, aiming at either
reducing the disease pressure or avoiding infec-
tion even if inoculum is abundant (Parry et al.
1995). Agronomic measures that aim at reduc-
ing the amount of inoculum are well known, for
instance by removal of plant remains from the
previous crop through careful ploughing. How-
ever, because of other reasons modern farms
nowadays often apply minimum- or no-till prac-
tices, which in turn enhance the disease pressure.
Chemical control is not straightforward and only
moderately effective, because current fungicides
slow down Fusarium growth to some extent only
and the time window of the fungicide application
is very narrow (Mesterhazy 2003), and fungicide
applications add to farming costs. Therefore, the
use of resistant cereal cultivars has to play a key
role in integrated Fusarium control and preven-
tion of mycotoxin contamination of cereals and
cereal products, as stated by Placinta et al. (1999:
22): “It is clear that legislation for the control of
these mycotoxins is now overdue and that fur-
ther work is required to exploit cereal genotypes
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