M. robertsii can translocate nitrogen from a colonized insect cadaver to a host plant
and in return receive sugar compounds from the plant. EIPF may enhance growth
promotion of plants by affecting photosynthetic efficiency. Endophytic colonization
of potato by M. brunneum promoted host plant growth by alleviating nutrient
deficiency effects (Krell et al. 2018). Additionally, Krasnoff et al. (2014) showed
that M. robertsii can produce siderophores (iron-chelating molecules) under irondeficient conditions which improved photosynthetic efficiency. M. brunneum
increased the availability of iron in calcareous and non-calcareous growth media
that resulted in an increase in root length and number of roots of sorghum plants
(Raya-Díaz et al. 2017a, 2017b). Endophytic colonization of sorghum plants by seed
and soil inoculation with M. brunneum increased chlorophyll content, even under
iron stress conditions, compared to the control (Raya-Díaz et al. 2017a, 2017b).
Endophytic colonization of M. anisopliae resulted in increased chlorophyll content
compared to control soybean plants (Khan et al. 2012).
The potential of Beauveria spp. to promote plant growth through nutrient supplementation and translocation has been reported in multiple studies. For example,
endophytic colonization of date palm by B. bassiana resulted in improved photosynthesis and energy metabolism (Gómez-Vidal et al. 2009). Endophytic B.
bassiana enhanced iron availability in calcareous and non-calcareous soil and
resulted in improved growth of sorghum (Raya-Díaz et al. 2017a, 2017b). Soil
fertility status, sources of nutrient, and crops management can also affect the
association of EIPF with plants. For example, B. bassiana detection was greater in
organically-managed fields where fertilization sources were compost, green and
animal manures compared to conventional fields where fertilization sources were
synthetic chemicals (Ramos et al. 2017). EIPF can help convert heavy metals to
easily-assimilated nutrients in the soil. For example, B. caledonica showed tolerance
to heavy metals and converted them to oxalates (Fomina et al. 2004) but it was not
evident whether those effects were due to direct or indirect effects of EIPF colonization. The effects of EIPF on plant nutrition and growth promotion vary among EIPF
species and strain or isolate, plants species and variety, and the composition of the
rhizosphere microbiome. In an experiment by Raad et al. (2019), one strain of
B. bassiana had a positive effect on the growth of A. thaliana, while the other strain
did not affect plant growth.
13.6 EIPF in Plant Protection Against Pests and Diseases
In addition to plant growth promotion and induction of plant defenses, EIPF have
been associated with indirect suppressive effects on pest insects and diseases. Soil
drenching with M. brunneum resulted in the improvement of plant growth
parameters at 7- and 35-days post-inoculation, and delayed the onset of reproduction, reduced the birth rate, and prolonged development time of the green peach
aphid (Myzus persicae) (Jaber and Araj 2018). Maize seed inoculated with
M. anisopliae showed increased stand density, stalk and foliage fresh weight, and
yield (Kabaluk and Ericsson 2007). The authors attributed these effects to the control
388
I. Ahmad et al.
and in return receive sugar compounds from the plant. EIPF may enhance growth
promotion of plants by affecting photosynthetic efficiency. Endophytic colonization
of potato by M. brunneum promoted host plant growth by alleviating nutrient
deficiency effects (Krell et al. 2018). Additionally, Krasnoff et al. (2014) showed
that M. robertsii can produce siderophores (iron-chelating molecules) under irondeficient conditions which improved photosynthetic efficiency. M. brunneum
increased the availability of iron in calcareous and non-calcareous growth media
that resulted in an increase in root length and number of roots of sorghum plants
(Raya-Díaz et al. 2017a, 2017b). Endophytic colonization of sorghum plants by seed
and soil inoculation with M. brunneum increased chlorophyll content, even under
iron stress conditions, compared to the control (Raya-Díaz et al. 2017a, 2017b).
Endophytic colonization of M. anisopliae resulted in increased chlorophyll content
compared to control soybean plants (Khan et al. 2012).
The potential of Beauveria spp. to promote plant growth through nutrient supplementation and translocation has been reported in multiple studies. For example,
endophytic colonization of date palm by B. bassiana resulted in improved photosynthesis and energy metabolism (Gómez-Vidal et al. 2009). Endophytic B.
bassiana enhanced iron availability in calcareous and non-calcareous soil and
resulted in improved growth of sorghum (Raya-Díaz et al. 2017a, 2017b). Soil
fertility status, sources of nutrient, and crops management can also affect the
association of EIPF with plants. For example, B. bassiana detection was greater in
organically-managed fields where fertilization sources were compost, green and
animal manures compared to conventional fields where fertilization sources were
synthetic chemicals (Ramos et al. 2017). EIPF can help convert heavy metals to
easily-assimilated nutrients in the soil. For example, B. caledonica showed tolerance
to heavy metals and converted them to oxalates (Fomina et al. 2004) but it was not
evident whether those effects were due to direct or indirect effects of EIPF colonization. The effects of EIPF on plant nutrition and growth promotion vary among EIPF
species and strain or isolate, plants species and variety, and the composition of the
rhizosphere microbiome. In an experiment by Raad et al. (2019), one strain of
B. bassiana had a positive effect on the growth of A. thaliana, while the other strain
did not affect plant growth.
13.6 EIPF in Plant Protection Against Pests and Diseases
In addition to plant growth promotion and induction of plant defenses, EIPF have
been associated with indirect suppressive effects on pest insects and diseases. Soil
drenching with M. brunneum resulted in the improvement of plant growth
parameters at 7- and 35-days post-inoculation, and delayed the onset of reproduction, reduced the birth rate, and prolonged development time of the green peach
aphid (Myzus persicae) (Jaber and Araj 2018). Maize seed inoculated with
M. anisopliae showed increased stand density, stalk and foliage fresh weight, and
yield (Kabaluk and Ericsson 2007). The authors attributed these effects to the control
388
I. Ahmad et al.