48
A. Dahiya et al.
Kshetri et al. (2018) isolated Arthrobacter luteolus S4C7, Enterobacter asburiae
S5C7, Klebsiella pneumoniae S4C9, S4C10, and S6C1, and K. quasipneumoniae
S6C2 from the rhizosphere of Allium hookeri. All the isolates released a substantial
amount of soluble phosphate.
3.5.2 Phosphate Solubilization by Endophytic Fungi
Several rhizospheric fungi such as arbuscular mycorrhizal (AM) fungi support plant
mineral nutrition in exchange for photosynthetic carbon and colonize the root zone
(Smith and Read 2008). The root endophytic fungus Piriformospora indica, which
is an anamorphic strain of the Sebacinales (Basidiomycota) was isolated from the
Thar Desert of India (Verma et al. 1998). P. indica can colonize roots and promote
plant growth independent of phosphate concentrations in the soil (Yadav et al. 2010).
Nath et al. (2012) isolated P-solubilizing endophytic Penicillium species from tea
leaves which showed significant phosphate solubilizing activity with an increase of
acidity of the medium. The decrease in the pH of the medium was associated with
an increased amount of available P in the medium.
Dark septate endophytes (DSE) are root colonizing soil fungi, which establish a
wide range of symbiotic interactions with the host plants. Occurrence of these fungi
has been associated with more than 600 plant species, including non-mycorrhizal
plants (Mandyam and Jumpponen 2005; Sieber and Grünig 2006). They can grow
in both biotrophic and saprophytic ways, hence have different effects on their hosts
(Mandyam et al. 2012). Barrow and Osuna (2002) showed that Aspergillus ustus
(DSE strain) can solubilize soil phosphate and increase P availability to Atriplex
canescens (Hernandez et al. 2011; Rinu and Pandey 2010). Bashan et al. (2013)
isolated DSE fungi from wheat (T. aestivum) and two forages (Panicum coloratum
and Chloris gayana) which solubilized calcium, aluminum, and iron phosphates,
in vitro methodologies. Rinu et al. (2013) reported that the carbon and nitrogen
sources can influence the phosphate solubilizing efficiency of the fungi. Comparatively, the efficiency of the strain of Ophiosphaerella sp. was found similar to that of
the filamentous fungus Paecilomyces lilacinus.
Spagnoletti et al. (2017) isolated dark septate endophytes from the roots of wheat
(Triticum aestivum) and forage crops Panicum coloratum and Chloris gayana, grown
in slightly acidic and alkaline soils of Argentina. The isolates showed the ability
to solubilize calcium phosphate, three strains solubilized aluminum phosphate,
and none of them solubilized iron phosphate on solid media. Maximum calcium
phosphate solubilization was carried out by Ophiosphaerella sp., Cochliobolus sp.,
and Setosphaeria rostrata. Endophytic strains Drechslera sp. and Ophiosphaerella
herpotricha showed maximum aluminum phosphate solubilization. Priyadharsini
and Muthukumar (2017) isolated Curvularia geniculata, a dark septate endophytic fungus from Parthenium hysterophorus L. to solubilize different sources of
phosphorus.
A. Dahiya et al.
Kshetri et al. (2018) isolated Arthrobacter luteolus S4C7, Enterobacter asburiae
S5C7, Klebsiella pneumoniae S4C9, S4C10, and S6C1, and K. quasipneumoniae
S6C2 from the rhizosphere of Allium hookeri. All the isolates released a substantial
amount of soluble phosphate.
3.5.2 Phosphate Solubilization by Endophytic Fungi
Several rhizospheric fungi such as arbuscular mycorrhizal (AM) fungi support plant
mineral nutrition in exchange for photosynthetic carbon and colonize the root zone
(Smith and Read 2008). The root endophytic fungus Piriformospora indica, which
is an anamorphic strain of the Sebacinales (Basidiomycota) was isolated from the
Thar Desert of India (Verma et al. 1998). P. indica can colonize roots and promote
plant growth independent of phosphate concentrations in the soil (Yadav et al. 2010).
Nath et al. (2012) isolated P-solubilizing endophytic Penicillium species from tea
leaves which showed significant phosphate solubilizing activity with an increase of
acidity of the medium. The decrease in the pH of the medium was associated with
an increased amount of available P in the medium.
Dark septate endophytes (DSE) are root colonizing soil fungi, which establish a
wide range of symbiotic interactions with the host plants. Occurrence of these fungi
has been associated with more than 600 plant species, including non-mycorrhizal
plants (Mandyam and Jumpponen 2005; Sieber and Grünig 2006). They can grow
in both biotrophic and saprophytic ways, hence have different effects on their hosts
(Mandyam et al. 2012). Barrow and Osuna (2002) showed that Aspergillus ustus
(DSE strain) can solubilize soil phosphate and increase P availability to Atriplex
canescens (Hernandez et al. 2011; Rinu and Pandey 2010). Bashan et al. (2013)
isolated DSE fungi from wheat (T. aestivum) and two forages (Panicum coloratum
and Chloris gayana) which solubilized calcium, aluminum, and iron phosphates,
in vitro methodologies. Rinu et al. (2013) reported that the carbon and nitrogen
sources can influence the phosphate solubilizing efficiency of the fungi. Comparatively, the efficiency of the strain of Ophiosphaerella sp. was found similar to that of
the filamentous fungus Paecilomyces lilacinus.
Spagnoletti et al. (2017) isolated dark septate endophytes from the roots of wheat
(Triticum aestivum) and forage crops Panicum coloratum and Chloris gayana, grown
in slightly acidic and alkaline soils of Argentina. The isolates showed the ability
to solubilize calcium phosphate, three strains solubilized aluminum phosphate,
and none of them solubilized iron phosphate on solid media. Maximum calcium
phosphate solubilization was carried out by Ophiosphaerella sp., Cochliobolus sp.,
and Setosphaeria rostrata. Endophytic strains Drechslera sp. and Ophiosphaerella
herpotricha showed maximum aluminum phosphate solubilization. Priyadharsini
and Muthukumar (2017) isolated Curvularia geniculata, a dark septate endophytic fungus from Parthenium hysterophorus L. to solubilize different sources of
phosphorus.