278
B. N. Aloo et al.
et al. 2014). Serratia sp. and Pseudomonas sp. from rice have been recently reported
to produce siderophores by Yasmin et al. (2016). Siderophore-producing endophytic P. agglomerans from peanuts (Taurian et al. 2013), and in turmeric (Kumar
et al. 2016) have also been reported. The endophytic Bacillus sp. and P. putida
were also associated with siderophore production. Similar studies on pepper endophytic Paenibacillis polymyxa by Phi et al. (2010) also exhibited such abilities by
Vendan et al. (2010). The endophytic bacteria such as B. cereus, B. flexus, B. megaterium, Lysinibacillus fusiformis, L. sphaericus, Microbacterium phyllosphaerae,
Micrococcus luteus isolated from maize also showed excellent siderophore production. Investigations by Youseif (2018) also demonstrated siderophore production
capabilities by wheat-root endophytic Stenotrophomonas maltophilia, Chryseobacterium sp, Falvobacterium sp., and Pseudoxanthomonas mexicana. In another study,
Maheshwari et al. (2019b), characterized siderophore-producing endophytic bacteria
from chickpea (Cicer arietinum) and pea (Pisum sativum). Earlier, Wani and Khan
(2010) stated that chickpea endophytic Pseudomonas sp. was one of the dominant
siderophore-producing genera of the plant. Patel et al. (2017b), observed endophytic
rhizobacterial isolates identified as Bacillus, Klebsiella, Microbacterium, and Enterobacter species which showed excellent siderophore production abilities. Similarly,
siderophore-producing endophytes have also been isolated from maize and canola
(Ghavami et al. 2017), corn (Szilagyi-Zecchin et al. 2014), banana, etc. (Ouma et al.
2014).
Siderophore-producing endophytes are important to crops not only directly by
improving Fe availability for plant uptake but also indirectly by depriving Fe required
to plant pathogens (Chhabra and Dowling 2017; Aloo et al. 2019b). The completed
genome analyses of endophytic microbes like Enterobacter species have shown that
they contain a large number of genes that code for siderophore transporter proteins
(Taghavi et al. 2010). The production of siderophores is a classic example of how
rhizobacteria can improve Fe availability in the plant rhizosphere and due to its
indisputable role in plant nutrition, further investigations on siderophore-producing
rhizobacteria are necessary (Aloo et al. 2019a).
12.3 Ecological Significance of Endophytes in Mineral
Nutrients Acquisition by Plants
Endophytic rhizobacteria are considered as sub-sets of rhizosphere microbiome that
have acquired the ability to colonize plant root tissues and exhibit specialized and
unique lifestyles (Compant et al. 2010; Dheeman et al. 2017). Despite their special
interaction with plants, endophytes share all the important PGP traits with other
rhizobacteria (Compant et al. 2005). However, they possess characteristics that are
distinct from rhizospheric bacteria, suggesting that not all rhizospheric bacteria
can enter plants, and/or that once inside their hosts, they change their lifestyles
to adapt to internal habitats within plants (Monteiro et al. 2012; Sessitsch et al.
B. N. Aloo et al.
et al. 2014). Serratia sp. and Pseudomonas sp. from rice have been recently reported
to produce siderophores by Yasmin et al. (2016). Siderophore-producing endophytic P. agglomerans from peanuts (Taurian et al. 2013), and in turmeric (Kumar
et al. 2016) have also been reported. The endophytic Bacillus sp. and P. putida
were also associated with siderophore production. Similar studies on pepper endophytic Paenibacillis polymyxa by Phi et al. (2010) also exhibited such abilities by
Vendan et al. (2010). The endophytic bacteria such as B. cereus, B. flexus, B. megaterium, Lysinibacillus fusiformis, L. sphaericus, Microbacterium phyllosphaerae,
Micrococcus luteus isolated from maize also showed excellent siderophore production. Investigations by Youseif (2018) also demonstrated siderophore production
capabilities by wheat-root endophytic Stenotrophomonas maltophilia, Chryseobacterium sp, Falvobacterium sp., and Pseudoxanthomonas mexicana. In another study,
Maheshwari et al. (2019b), characterized siderophore-producing endophytic bacteria
from chickpea (Cicer arietinum) and pea (Pisum sativum). Earlier, Wani and Khan
(2010) stated that chickpea endophytic Pseudomonas sp. was one of the dominant
siderophore-producing genera of the plant. Patel et al. (2017b), observed endophytic
rhizobacterial isolates identified as Bacillus, Klebsiella, Microbacterium, and Enterobacter species which showed excellent siderophore production abilities. Similarly,
siderophore-producing endophytes have also been isolated from maize and canola
(Ghavami et al. 2017), corn (Szilagyi-Zecchin et al. 2014), banana, etc. (Ouma et al.
2014).
Siderophore-producing endophytes are important to crops not only directly by
improving Fe availability for plant uptake but also indirectly by depriving Fe required
to plant pathogens (Chhabra and Dowling 2017; Aloo et al. 2019b). The completed
genome analyses of endophytic microbes like Enterobacter species have shown that
they contain a large number of genes that code for siderophore transporter proteins
(Taghavi et al. 2010). The production of siderophores is a classic example of how
rhizobacteria can improve Fe availability in the plant rhizosphere and due to its
indisputable role in plant nutrition, further investigations on siderophore-producing
rhizobacteria are necessary (Aloo et al. 2019a).
12.3 Ecological Significance of Endophytes in Mineral
Nutrients Acquisition by Plants
Endophytic rhizobacteria are considered as sub-sets of rhizosphere microbiome that
have acquired the ability to colonize plant root tissues and exhibit specialized and
unique lifestyles (Compant et al. 2010; Dheeman et al. 2017). Despite their special
interaction with plants, endophytes share all the important PGP traits with other
rhizobacteria (Compant et al. 2005). However, they possess characteristics that are
distinct from rhizospheric bacteria, suggesting that not all rhizospheric bacteria
can enter plants, and/or that once inside their hosts, they change their lifestyles
to adapt to internal habitats within plants (Monteiro et al. 2012; Sessitsch et al.