Endophytes Crop Productivity and Protection Volume 2 (Sustainable Development and Biodiversity)

agricultural crops (Table8.2). Efforts have been made in searching for biostimu-

lator/biofertilizer for crop production, and natural biocontrol agents for crop pro-

tection. Endophytic actinobacteria, especially those belonging to the genus

Streptomyceshave become an important microbial source for application in various

crops, such as Lycopersicon esculentum, Triticum aestivum, Medicago sativa,

Brassica rapa,Citrus reticulate,Oryza sativa,andZea mays(Table8.2). Several

studies indicate that endophytic actinobacterial species are able to enhance the

performance of agricultural crops by employing a range of mechanisms, such as

nitrogenfixation (Le et al. 2016 ), solubilization of phosphate (Jog et al. 2014 ),

production of phytohormones (El-Tarabily et al. 2009 ; Goudjal et al. 2013 ; Meguro

et al. 2006 ), siderophores (Hastuti et al. 2012 ; Rungin et al. 2012 ), hydrogen

cyanide (Passari et al. 2015 ), chitinase (Singh and Gaur 2016 ), ammonia (Passari

et al. 2015 ), antibiotics (Mingma et al. 2014 ), and other antibacterial and antifungal

metabolites (Cao et al. 2004 ; Costa et al. 2013 ; Goudjal et al. 2014 ). However, the

beneficial effects contributing to plant growth promotion and the level of biocontrol

achieved by various endophytic actinobacteria are mainly performed in laboratory

or identically controlled environmental conditions. In this regard, endophytic

actinobacteria possessing biofertilizer and biocontrol properties for commercial use

must be further tested for practical agricultural applications. Studies are, therefore,

needed to evaluate the functions of these endophytic actinobacteria in terms of
enhancing host plant growth, as well as inducing systemic resistance and antibiosis

activity against phytopathogens infield trials.

Table 8.2 Enhanced performance of agricultural crops by endophytic actinobacteria

Endophytic

actinobacteria

Isolated from Plant beneficial trait Effect References

Streptomycesspp. Lycopersicon

esculentum

Production of

antibacterial and

antifungal

metabolites

Growth promotion

and enhanced

disease resistance of

tomato seedlings,

but not in cucumber

seedlings

Cao et al.

( 2004 )

Streptomycesspp. Zea mays Growth inhibition of

phytopathogenic

fungi

Isolate 16R3B was

able to reduce up to

71% damping-off

incidence whereas

isolate 14F1D/2

reduced disease

incidence by 36%

Costa et al.

( 2013 )

Actinoplanes

campanulatus,

Micromonospora

chalcea,

Streptomyces

spiralis

N.i. Production of IAA

and indole-3-pyruvic

acid

Promoted plant

growth and

suppressed

pathogenic activities

ofPythium

aphanidermatumon

seedling and mature

cucumber

El-Tarabily

et al. ( 2009 )

(continued)

8 Endophytic Actinobacteria for Sustainable Agricultural Applications 179

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