10 Endophytic Actinobacteria Associated …
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maximum IAA of 11.12 µg/ml (Lasudee et al. 2018). In addition, Leifsonia poae
associated with Glomus mosseae produced IAA at 8.3 µg/ml (Mohandas et al. 2013).
Similarly, Gibberellin (GA) is another plant hormone stimulating stem elongation,
bolting, and flowering (Hamadi and Mohammadipanah 2015). Various species such
as S. fradiae, S. cinnamonenesis, S. canus, and L. poae isolated from Glomus mosseae
were reported to produce gibberellin in culture broth with the maximum GA of
12 µg/ml. reported by S. canus (Mohandas et al. 2013).
10.4 Beneficial Effects of Endophytic Actinobacteria
on Plant
Actinobacteria can promote plant growth by their ability to produce plant growth
regulators. Several endophytic actinobacteria were reported to produce plant growth
regulators such as IAA or siderophores in vitro as a result of these can promote
plant growth under controlled environmental conditions (El-Tarabily et al. 2009;
Mohandas et al. 2013). Mohandas et al. 2013 tested five actinobacteria associated
with G. mosseae namely S. fradiae, S. avermitilis, S. cinnamonensis, S. canus, and
L. poae for growth promotion of guava (Psidium guajava L.). Except for S. fradiae
all of them increased height, leaf area, fresh weight, and dry weight of 10 months
guava seedlings. Also, these actinobacteria promoted the growth of pomegranate,
increased shoot and root length, leaf area, and total biomass in 6-month-old seedlings
(Poovarasan et al. 2013). S. canus, increased dry weight over control possibly by its
ability to produce growth hormones IAA and GA3 in vitro. Endophytic actinobacteria
from Gigaspora margarita spores have recently been reported to promote the growth
of alfalfa (Medicago sativa) seedlings. Similarly, Curtobacterium luteum M0608247 and Mycobacterium mucogenicum M060824-8 enhanced fresh and dry weight of
leaf/stem and root fresh weight of alfalfa seedlings. Besides, these two actinobacteria
also increased AMF colonization in alfalfa root (Long et al. 2017).
Funneliformis belongs to a member of AMF in the family Glomeraceae, which
form symbiotic relationships with many angiosperm plant roots. It was formerly
known as Glomus mosseae until the genus Funneliformis was established in the year
2010 with F. mosseae as a type species (Schubler and Walker 2010). Being its wide
occurrence and richness of literature, F. mosseae widely used as bioinoculant (Kruger
et al. 2012). Its symbiosis with host plants improves the nutrient uptake and provides
AM fungi with carbon sources (Rouphael et al. 2015; Wang et al. 2017; Begum et al.
2019).
In the authors’ laboratory, S. thermocarboxydus spp have been isolated from F.
mosseae spores (Fig. 10.1). The isolate S3 exhibited as plant growth-promoting
bacteria due to its ability to produce IAA, ACC deaminase, and siderophore and
solubilize insoluble phosphate. Interestingly, this species grew at a low water activity
(a w 0.919) and was able to produce IAA under such conditions in vitro (Lasudee et al.
2018). Mung bean (Vigna radiata) inoculated with S. thermocarboxydus isolate S3
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maximum IAA of 11.12 µg/ml (Lasudee et al. 2018). In addition, Leifsonia poae
associated with Glomus mosseae produced IAA at 8.3 µg/ml (Mohandas et al. 2013).
Similarly, Gibberellin (GA) is another plant hormone stimulating stem elongation,
bolting, and flowering (Hamadi and Mohammadipanah 2015). Various species such
as S. fradiae, S. cinnamonenesis, S. canus, and L. poae isolated from Glomus mosseae
were reported to produce gibberellin in culture broth with the maximum GA of
12 µg/ml. reported by S. canus (Mohandas et al. 2013).
10.4 Beneficial Effects of Endophytic Actinobacteria
on Plant
Actinobacteria can promote plant growth by their ability to produce plant growth
regulators. Several endophytic actinobacteria were reported to produce plant growth
regulators such as IAA or siderophores in vitro as a result of these can promote
plant growth under controlled environmental conditions (El-Tarabily et al. 2009;
Mohandas et al. 2013). Mohandas et al. 2013 tested five actinobacteria associated
with G. mosseae namely S. fradiae, S. avermitilis, S. cinnamonensis, S. canus, and
L. poae for growth promotion of guava (Psidium guajava L.). Except for S. fradiae
all of them increased height, leaf area, fresh weight, and dry weight of 10 months
guava seedlings. Also, these actinobacteria promoted the growth of pomegranate,
increased shoot and root length, leaf area, and total biomass in 6-month-old seedlings
(Poovarasan et al. 2013). S. canus, increased dry weight over control possibly by its
ability to produce growth hormones IAA and GA3 in vitro. Endophytic actinobacteria
from Gigaspora margarita spores have recently been reported to promote the growth
of alfalfa (Medicago sativa) seedlings. Similarly, Curtobacterium luteum M0608247 and Mycobacterium mucogenicum M060824-8 enhanced fresh and dry weight of
leaf/stem and root fresh weight of alfalfa seedlings. Besides, these two actinobacteria
also increased AMF colonization in alfalfa root (Long et al. 2017).
Funneliformis belongs to a member of AMF in the family Glomeraceae, which
form symbiotic relationships with many angiosperm plant roots. It was formerly
known as Glomus mosseae until the genus Funneliformis was established in the year
2010 with F. mosseae as a type species (Schubler and Walker 2010). Being its wide
occurrence and richness of literature, F. mosseae widely used as bioinoculant (Kruger
et al. 2012). Its symbiosis with host plants improves the nutrient uptake and provides
AM fungi with carbon sources (Rouphael et al. 2015; Wang et al. 2017; Begum et al.
2019).
In the authors’ laboratory, S. thermocarboxydus spp have been isolated from F.
mosseae spores (Fig. 10.1). The isolate S3 exhibited as plant growth-promoting
bacteria due to its ability to produce IAA, ACC deaminase, and siderophore and
solubilize insoluble phosphate. Interestingly, this species grew at a low water activity
(a w 0.919) and was able to produce IAA under such conditions in vitro (Lasudee et al.
2018). Mung bean (Vigna radiata) inoculated with S. thermocarboxydus isolate S3