Agriculture Reference
In-Depth Information
Control
Control
a
b
Control
Control
d
c
Fig. 10.1
Antifungal activity expression of certain unidentified PS organisms: (
a
) The volatile
compounds inhibiting the growth of phytopathogenic fungi in a dual plate assay, (
b
) the metabolite
produced by bacteria inhibiting the growth of phytopathogenic fungi, (
c
) the antifungal metabolite
that inhibit the growth of fungi in a well-diffusion method, and (
d
) cyanogenic compound (HCN)
production by PS bacterial strain
10.3
Importance of PSM in the Management of Plant
Diseases: An Overview
The production and release of certain secondary metabolites by PSM in the
rhizosphere (Khan et al.
2013
) deleteriously affects the soilborne phytopathogens
(Vassilev et al.
2006
; Postma et al.
2010
) (Fig.
10.1
), and some of the pathogen-
suppressing metabolites, for example, siderophores (Ahmad et al.
2013
), antibiotics
(de Werra et al.
2009
), and lytic enzymes (Kumar et al.
2013
), produced by PSM
in vitro are listed in Table
10.2
.
In a most recent study, Son et al. (
2014
) evaluated the effects of PS bacteria,
identified by 16S rDNA sequence analysis as
Kluyvera cryocrescens
KUDC1771
and
Brevibacterium iodinum
KUDC1716, on growth promotion of pepper and
antagonistic activity against a gray leaf spot disease pathogen,
Stemphylium
lycopersici
. The selected PS bacteria enhanced the growth of
K. cryocrescens
KUDC1771 inoculated plants. Of these,
B. iodinum
KUDC1716 significantly
decreased the severity of gray leaf spot disease and concurrently enhanced the
plant health. Also, KUDC1716 strain of
B. iodinum
considerably increased the
expression of pathogenesis-related (PR) protein genes including CaPR4 and
CaChi2 in the absence of pathogen suggesting that
B. iodinum
could induce defense
response against
S. lycopersici
and, hence, it may be used as a potential biological
control agent. Similarly, PS bacteria,
Janibacter
,
Pseudomonas
, and
Bacillus
iso-
lated from Uruguay, Chile, and Argentina produced siderophores and exopolysac-
charides (EPS), hydrolyzed starch, and demonstrated biological control activity
