Agriculture Reference
In-Depth Information
powdery mildew (
Erysiphe necator
), which are generally prevented by phytochem-
ical application. In addition, grapes may also bear saprophytic moulds
(
Cladosporium
spp.,
Aspergillus
spp.,
Penicillium
spp.) responsible for several
grape rots or mycotoxin production. However, these fungi do not have the ability
to grow in wines, and their effect on wine quality is due to grape damage (Barata
et al.
2012
).
Grain crops are also susceptible to fungal contamination, being
Aspergillus
,
Penicillium
,
Fusarium
, and
Alternaria
the most frequent genera. In these products,
moulds are responsible for off-flavor formation and contribute to heating and loss in
dry matter in grains through the utilization of carbohydrates as an energy source,
degradation of lipids and proteins, production of volatile metabolites, and produc-
tion of allergenic compounds. This causes a reduction in the quality of animal feed
and seed (Cabral et al.
2013
). In addition, toxigenic fungi are a major problem in
cereal crops as they produce a large number of toxic metabolites contaminating
plants and food products. Many phytopathogenic and spoilage fungi also cause
several potential carcinogenic and mutagenic diseases in humans and animals due
to mycotoxin production. These secondary metabolites are produced by filamentous
fungi as a natural protection. Mycotoxins are usually thermostable (above 100
C)
and thus can be transferred to food, even after microbial stabilization steps, such as
heating and extrusion. Consequently, humans and animals are exposed to their toxic
effects (Beretta et al.
2002
; Oliveira et al.
2014
). Inhibition of fungal growth in
crops, fresh fruits, and vegetables is therefore necessary to reduce the risk to human
and animal health. However, it is important to note that partial inhibition of fungal
growth, such as reduction of fungal growth rate, could enhance mycotoxin produc-
tion as a response of the mould to stress (Cabral et al.
2013
).
Spoilage bacteria cause food crop deterioration and result in unpleasant odors,
tastes, and textures. For example, these microorganisms can cause fruits and
vegetables to become mushy or slimy or to develop a bad odor (Gram
et al.
2002
). Several types of bacteria are associated with the spoilage of fresh
products, and most of them are pathogenic to the plant. For example, the gram-
negative bacterium
Erwinia carotovora
is a common phytopathogen attacking
virtually every vegetable type (Tournas
2005
).
E. carotovora
is frequently associ-
ated with rot disorders in potatoes, carrots, tomatoes, and other vegetables, and
infections often result in a complete loss of these crops. Infection by
Clavibacter
michiganensis
, a gram-positive bacterium, causes bacterial wilt in diverse agricul-
turally important plants, including a variety of fruits and vegetables (Fatmi and
Schaad
2002
). Bacteria belonging to the genera
Pectobacterium
and
Dickeya
are
causal agents of blackleg and tuber soft of potato. In seed potato production, these
diseases are next in economic importance to bacterial wilt caused by
Ralstonia
solanacearum
and before ring rot and common scab caused by
Clavibacter
michiganensis
or
Streptomyces scabies
, respectively (Czajkowski et al.
2011
).
Dickeya zeae
is the causal agent of devastating rice foot rot disease, which is a
major concern of
the agricultural
industry in rice-growing regions (Zhou
et al.
2011
).
