Agriculture Reference
In-Depth Information
Ingle and Deshmukh
2010
; Yaqub and Shahazad
2011
; Parikh and Jha
2012
;
Geethapriya and Krishnaveni
2012
) by virtue of synthesizing siderophores
(Ahmad et al.
2013
; Walia et al.
2013
), antibiotics (Compant et al.
2005
), lytic
enzymes (Postma et al.
2010
; Kumar et al.
2012
) or cyanogenic compounds
(Hallman et al.
1997
; Sturz et al.
2000
; Welbaum et al.
2004
; Ahmad et al.
2013
),
etc. In general, the symbiotic PGPR, for example, rhizobia (Khan et al.
2002
), free-
living PGPR (Khan et al.
2006
), and endophytic PGPR, have been reported to
continuously promote plant growth by restricting/inhibiting the populations of
disease-causing phytopathogens (Sturz et al.
2000
; Lodewyckx et al.
2002
;
Dobbelaere et al.
2003
). Experimental evidence that is consistent with the involve-
ment of PS biocontrol bacteria in the suppression of fungal pathogen causing plant
disease comes from several different studies. For example, P-solubilizing fluores-
cent pseudomonads demonstrated a profound antifungal activity against
R. solani
and effectively protected the pepper plants against damping off under in vivo
conditions through the release of disease inhibiting lytic enzymes (chitinase and
β
-1,3-glucanase), siderophores, and HCN (Rajkumar et al.
2008
). On the other
hand, one study observed that ACC deaminase-producing P-solubilizing strain
BPR7 of
Bacillus
sp. recovered from Indian Himalayan region was most efficient
at protecting plants against fungal pathogens like
M. phaseolina
,
Fusarium
oxysporum
,
F. solani
,
Sclerotinia sclerotiorum
,
R. solani
, and
Colletotrichum
sp. (Kumar et al.
2013
).
10.2 Examples of Plant Pathogenic Bacteria, Fungi,
and Nematode Causing Plant Diseases
Plant diseases are reported to cause economical loss of billions of dollars by
reducing crop yields and result in poorer quality produce. When pesticides are
used to control phytopathogens, it contaminates food grains which later on become
nonconsumable for humans (Guo et al.
2013
). Taking into account the magnitude of
yield losses by the phytopathogens, a survey was conducted to identify the most
prominent fungi, bacteria, and nematodes able to cause diseases onto plants, and the
results of this finding were published in
Molecular Plant Pathology
Journal. The
top 10 fungi (Ralph et al.
2012
), bacteria (Mansfiels et al.
2012
), and nematodes
(Jones et al. (
2013
) inflicting heavy losses to crops are listed in Table
10.1
. Bacteria
which were very close to top ten listed bacteria but did not find place in top ten club
included
Clavibacter michiganensis
(
michiganensis
and
sepedonicus
),
Pseudomo-
nas savastanoi
, and
Candidatus liberibacter asiaticus
.
