cf. psalliotae colonized palm plants and induced stress and defense-related proteins,
improved photosynthesis and energy metabolism (Gómez-Vidal et al. 2009).
L. psalliotae enhanced the growth of cardamom (Elettaria cardamomum) through
production of siderophores, indole acetic acid (IAA), and increased chlorophyll
content (Kumar et al. 2018). Isaria javanica pf185 promoted the growth of tobacco
(Nicotiana tabacum) by enhanced root branching and root hair formation and the
authors attributed these effects to fungal volatiles (Lee and Kim 2019).
Multiple mechanisms have been described that contribute to plant growth promotion effects, including protection from pest insects and phytopathogens; nutrient
translocation and assimilation, plant defense modulation; production of
phytohormones and biologically-active metabolites, and improved photosynthesis
and energy metabolism (Ahmad et al. 2020b; Behie et al. 2012, 2017; Cherry et al.
2004; Gómez-Vidal et al. 2009; Khan et al. 2012; Kumar et al. 2018; Liao et al.
2017). Several studies reported that EIPF colonization promoted plant growth
through the suppression of herbivory and plant diseases. For example, under laboratory conditions, M. brunneum colonization of tomato effectively controlled the larval
growth of the elaterid click beetle, Agriotes obscurus (Mayerhofer et al. 2017).
Inoculation of maize with B. bassiana resulted in suppression of the noctuid stemborer (Sesamia calamistis) and looper, Rachiplusia nu (Cherry et al. 2004; Russo
et al. 2019). M. brunneum acted antagonistically against the olive phytopathogens,
Verticillium dahliae and Phytophthora megasperma (Lozano-Tovar et al. 2017).
B. bassiana produced IAA that promoted plant growth by inducing changes in root
architecture that may facilitate a symbiotic relationship with the host plant (Liao
et al. 2017).
Another mechanism by which EIPF may benefit plants is nutrient transfers from
infected insects in the soil, linking the pathogenic and endophytic functions of EIPF.
Using radioisotopic labeling, Behie et al. (2012) discovered that M. robertsii transferred nitrogen from a fungus-colonized cadaver to a plant through a mycelial
association with roots. In return, M. robertsii received sugar as a source of carbon
from the plant (Behie et al. 2017). If this is a common phenomenon in nature,
improved plant nutrient status associated with EIPF may positively impact plant
energy metabolism and photosynthetic efficiency under nutrient deficient conditions
(Gómez-Vidal et al. 2009; Krell et al. 2018) (Fig. 13.1).
13.4 The Role of EIPF in Plant Defense
Plant responses to stress have been well-studied and include morphological, physiological, cellular, and molecular changes (Dastogeer 2018; Gray and Brady 2016).
Abiotic and biotic stresses can impact microbes directly, altering microbial population, community composition, and the processes they mediate (Frey et al. 2013;
Hagerty et al. 2014; Karhu et al. 2014). The outcome of plant–endophyte
interactions depends on the identity of the plant and fungal symbionts (Dastogeer
2018). Mutualistic plant–microbe interactions can confer plants with molecular
384
I. Ahmad et al.
improved photosynthesis and energy metabolism (Gómez-Vidal et al. 2009).
L. psalliotae enhanced the growth of cardamom (Elettaria cardamomum) through
production of siderophores, indole acetic acid (IAA), and increased chlorophyll
content (Kumar et al. 2018). Isaria javanica pf185 promoted the growth of tobacco
(Nicotiana tabacum) by enhanced root branching and root hair formation and the
authors attributed these effects to fungal volatiles (Lee and Kim 2019).
Multiple mechanisms have been described that contribute to plant growth promotion effects, including protection from pest insects and phytopathogens; nutrient
translocation and assimilation, plant defense modulation; production of
phytohormones and biologically-active metabolites, and improved photosynthesis
and energy metabolism (Ahmad et al. 2020b; Behie et al. 2012, 2017; Cherry et al.
2004; Gómez-Vidal et al. 2009; Khan et al. 2012; Kumar et al. 2018; Liao et al.
2017). Several studies reported that EIPF colonization promoted plant growth
through the suppression of herbivory and plant diseases. For example, under laboratory conditions, M. brunneum colonization of tomato effectively controlled the larval
growth of the elaterid click beetle, Agriotes obscurus (Mayerhofer et al. 2017).
Inoculation of maize with B. bassiana resulted in suppression of the noctuid stemborer (Sesamia calamistis) and looper, Rachiplusia nu (Cherry et al. 2004; Russo
et al. 2019). M. brunneum acted antagonistically against the olive phytopathogens,
Verticillium dahliae and Phytophthora megasperma (Lozano-Tovar et al. 2017).
B. bassiana produced IAA that promoted plant growth by inducing changes in root
architecture that may facilitate a symbiotic relationship with the host plant (Liao
et al. 2017).
Another mechanism by which EIPF may benefit plants is nutrient transfers from
infected insects in the soil, linking the pathogenic and endophytic functions of EIPF.
Using radioisotopic labeling, Behie et al. (2012) discovered that M. robertsii transferred nitrogen from a fungus-colonized cadaver to a plant through a mycelial
association with roots. In return, M. robertsii received sugar as a source of carbon
from the plant (Behie et al. 2017). If this is a common phenomenon in nature,
improved plant nutrient status associated with EIPF may positively impact plant
energy metabolism and photosynthetic efficiency under nutrient deficient conditions
(Gómez-Vidal et al. 2009; Krell et al. 2018) (Fig. 13.1).
13.4 The Role of EIPF in Plant Defense
Plant responses to stress have been well-studied and include morphological, physiological, cellular, and molecular changes (Dastogeer 2018; Gray and Brady 2016).
Abiotic and biotic stresses can impact microbes directly, altering microbial population, community composition, and the processes they mediate (Frey et al. 2013;
Hagerty et al. 2014; Karhu et al. 2014). The outcome of plant–endophyte
interactions depends on the identity of the plant and fungal symbionts (Dastogeer
2018). Mutualistic plant–microbe interactions can confer plants with molecular
384
I. Ahmad et al.