324
G. Garg et al.
in rhizosphere region, increases Fe transportation efficiency within the plant for the
root and shoot growth (Verma et al. 2011; Crowley 2006). Gangwar and Kaur (2009)
and Rungin et al. (2012) isolated some bacteria [Escherichia coli from ryegrass
(Loliumperenne sp.)] and an endophytic fungus Streptomyces sp. from the roots of
Thai jasmine rice that enhances plant growth and significantly improved the root
and shoot biomass and lengths. It has been correlated that excessive accumulation of
heavy metals is toxic for most of the plants and responsible for the contamination of
soil which decreases soil fertility and soil microbial activity (McGrath et al. 1995). In
this context, hydroxamate type of siderophore present in soil will play an important
role to immobilize the metals and act as plant growth promoter.
7.2 Siderophore as inhibitor for phytopathogenic attack: Siderophore acts as
an inhibitor for phytopathogenic attacks and restrains the growth of phytopathogens.
Molecules of siderophores bind with iron and make it unavailable for the plant
pathogens (Beneduzi et al. 2012; Ahmed and Holmstrom 2014). Siderophores synthesized by Pseudomonas and Bacillus sp. (a type of rhizobacteria) inhibited the attack
of Phytophthora parasitica (Seuk et al.1988), Fusarium oxysporum veridianthi
(Buysens et al. 1996), Pythium ultimum (Hamdan et al. 1991), and Sclerotinia sclerotiorum (Mc Loughlin et al. 1992). For example: different strains of Pseudomonas
fluorescens (like A1, BK1, TL3B1) act as a biological controlling agent against
Erwinia carotovora and Fusarium oxysporum. F. oxysporum causes wilt diseases in
potatoes (Kloepper et al. 1980; Schippers et al. 1987).
7.3 Siderophore as Bioremediation: There is release of heavy metals and metalloids from petroleum industry, chemical industry, etc., which contaminates the soil
and water and for this siderophores is of prime prominence for metal bioremediation
apart from binding with ferric iron, siderophores also regulate the gelatinization the
other toxic metals, e.g., Cr
3+ , Al
3+ , Cu
2+ , Eu
3+ , and Pb
2+ via the production of pyoverdine siderophore (P. aeruginosa), azotochelin (Azotobacter vinelandii), schizokinen,
and N-di-oxyschizokinen production (Bacillus megaterium) stimulates molybdenum
and aluminium biosynthesis, respectively (Braud et al. 2009a, b; Duhme et al. 1998;
Hu and Boyer 1996). Specific siderophores showed very strong ligands affinity with
specific metallic ions and form siderophore–metal complex molecule, which depends
upon the ligand functionalities and siderophore–metal complex formation (Hernlem
et al. 1999).
7.4 Endophytes and their role in Fe (iron) management in soil: It has been
iterated that iron (Fe) is an essential element for plant growth and development.
PGPR can increase Fe absorption by plants through reduction of Fe (III) to Fe (II) at
the root surface. The bacterial strains with high Fe (III) reduction ability were able to
stimulate plant growth in vitro and on a broad level. Plants grown in inoculated soil
were generally bigger and with higher Fe content than those grown in sterilized soil.
This contributes significantly due to Fe absorption by plants likely through increased
Fe (III) reduction in the rhizosphere Valencia-Cantero et al. 2007. The role of bacterial
endophytes in the acquisition of iron (Fe) solubilization and acquisition systems by
plant-associated microbes with respect to improving plant growth and health used
to enhance the supply of iron often limiting nutrients to the host plant (Chhabra
and Dowling 2017). Siderophore-producing endophytes Arthrobacter sulfonivorans
G. Garg et al.
in rhizosphere region, increases Fe transportation efficiency within the plant for the
root and shoot growth (Verma et al. 2011; Crowley 2006). Gangwar and Kaur (2009)
and Rungin et al. (2012) isolated some bacteria [Escherichia coli from ryegrass
(Loliumperenne sp.)] and an endophytic fungus Streptomyces sp. from the roots of
Thai jasmine rice that enhances plant growth and significantly improved the root
and shoot biomass and lengths. It has been correlated that excessive accumulation of
heavy metals is toxic for most of the plants and responsible for the contamination of
soil which decreases soil fertility and soil microbial activity (McGrath et al. 1995). In
this context, hydroxamate type of siderophore present in soil will play an important
role to immobilize the metals and act as plant growth promoter.
7.2 Siderophore as inhibitor for phytopathogenic attack: Siderophore acts as
an inhibitor for phytopathogenic attacks and restrains the growth of phytopathogens.
Molecules of siderophores bind with iron and make it unavailable for the plant
pathogens (Beneduzi et al. 2012; Ahmed and Holmstrom 2014). Siderophores synthesized by Pseudomonas and Bacillus sp. (a type of rhizobacteria) inhibited the attack
of Phytophthora parasitica (Seuk et al.1988), Fusarium oxysporum veridianthi
(Buysens et al. 1996), Pythium ultimum (Hamdan et al. 1991), and Sclerotinia sclerotiorum (Mc Loughlin et al. 1992). For example: different strains of Pseudomonas
fluorescens (like A1, BK1, TL3B1) act as a biological controlling agent against
Erwinia carotovora and Fusarium oxysporum. F. oxysporum causes wilt diseases in
potatoes (Kloepper et al. 1980; Schippers et al. 1987).
7.3 Siderophore as Bioremediation: There is release of heavy metals and metalloids from petroleum industry, chemical industry, etc., which contaminates the soil
and water and for this siderophores is of prime prominence for metal bioremediation
apart from binding with ferric iron, siderophores also regulate the gelatinization the
other toxic metals, e.g., Cr
3+ , Al
3+ , Cu
2+ , Eu
3+ , and Pb
2+ via the production of pyoverdine siderophore (P. aeruginosa), azotochelin (Azotobacter vinelandii), schizokinen,
and N-di-oxyschizokinen production (Bacillus megaterium) stimulates molybdenum
and aluminium biosynthesis, respectively (Braud et al. 2009a, b; Duhme et al. 1998;
Hu and Boyer 1996). Specific siderophores showed very strong ligands affinity with
specific metallic ions and form siderophore–metal complex molecule, which depends
upon the ligand functionalities and siderophore–metal complex formation (Hernlem
et al. 1999).
7.4 Endophytes and their role in Fe (iron) management in soil: It has been
iterated that iron (Fe) is an essential element for plant growth and development.
PGPR can increase Fe absorption by plants through reduction of Fe (III) to Fe (II) at
the root surface. The bacterial strains with high Fe (III) reduction ability were able to
stimulate plant growth in vitro and on a broad level. Plants grown in inoculated soil
were generally bigger and with higher Fe content than those grown in sterilized soil.
This contributes significantly due to Fe absorption by plants likely through increased
Fe (III) reduction in the rhizosphere Valencia-Cantero et al. 2007. The role of bacterial
endophytes in the acquisition of iron (Fe) solubilization and acquisition systems by
plant-associated microbes with respect to improving plant growth and health used
to enhance the supply of iron often limiting nutrients to the host plant (Chhabra
and Dowling 2017). Siderophore-producing endophytes Arthrobacter sulfonivorans