2 Bioefficacy of Endophytes in the Control of Plant Diseases
23
F. oxysporum CanR-46 control the impact of S. sclerotiorum in Brassica napus,
demonstrating a 94.5% mycelial growth inhibition (Zhang et al. 2014).
Moreover, fungal endophytes have been proposed as sources of useful secondary
metabolites (Petrini et al. 1993; Schulz et al. 2002; Shukla et al. 2014). In this trend,
there is an interesting research field focused on the bioactive compounds produced
by endophytic fungi and their applications in agriculture, medicine, and industry
(Zhao et al. 2011). The use of endophytes to promote plant fitness could improve
the production of medicinal plants as well as their bioactive-derivate compounds in
medicinal plants (Jia et al. 2016).
Besides parasitism and antibiosis, Trichoderma spp. can manage to induce lipid
transferase proteins to confer defense against Phytophthora capsici (Bae et al. 2011).
Induction of systemic resistance was also evidenced by the activation of defenserelated enzymes on cucumber plants inoculated with a non-pathogenic strain of
Colletotrichum magna (Redman et al. 1999).
Timing is an important factor to ensure a successful biocontrol strategy. In this
trend, the order of arrival of endophytes and pathogens in Phaseolus lunatus was
analyzed (Adame-Álvarez et al. 2014). Interestingly, the antagonist effect of the
endophytes on the pathogen was only successful when the endophyte colonization occurs first; otherwise, endophyte inoculation after pathogen infection rather
facilitates disease development (Adame-Álvarez et al. 2014).
As mentioned earlier, fungal endophytes can trigger ISR in the host. The mechanisms involved in this response are analogous to those imposed by mycorrhizal fungi,
involving the SA and JA signaling pathways (Jung et al. 2012; Pozo and AzcónAguilar 2007). In a previous study, it has been demonstrated that JA is necessary
for the biocontrol response in tomato triggered by the infection of a non-pathogenic
F. solani strain (Kavroulakis et al. 2007). In this system, F. solani can elicit ISR
against Septoria lycopersici by expression of pathogenesis-related (PR) genes in
roots. In agreement with the effects reported for bacterial endophytes, it has been
demonstrated that ethylene, as well as JA, is required for ISR triggered by fungal
endophytes (Kavroulakis et al. 2007). Nevertheless, a recent study has demonstrated
that inoculation with an endophytic Fusarium strain can trigger the systemic response
independently of JA, SA, and ethylene (Constantin et al. 2019).
As exposed above, the interactions between grasses and fungi belonging to
the Clavicipitaceous group constitute protective mutualisms. The effect of the
endophyte-infected grasses (E+) on the dynamic population of the insect pest has been
extensively compared with the non-endophyte infected grasses (E−). For example,
Lolium multiflorum-E. occultans interaction reduces the aphid population by 64%
and the nymph by 81%, consequently, the fecundity of the aphid populations is
strongly affected (Bastias et al. 2017b).
Complementary to the protection conferred by the alkaloids production, recent
studies on the endophyte-grass interactions has demonstrated the ability of the endophyte to enhance the plant immunity through mechanisms involving the JA-mediated
response, by the promotion of JA-signaling and repression of SA-signaling defenses
(Bastias et al. 2017a). Besides, the interaction between Lolium pernenne-Epichlöe
23
F. oxysporum CanR-46 control the impact of S. sclerotiorum in Brassica napus,
demonstrating a 94.5% mycelial growth inhibition (Zhang et al. 2014).
Moreover, fungal endophytes have been proposed as sources of useful secondary
metabolites (Petrini et al. 1993; Schulz et al. 2002; Shukla et al. 2014). In this trend,
there is an interesting research field focused on the bioactive compounds produced
by endophytic fungi and their applications in agriculture, medicine, and industry
(Zhao et al. 2011). The use of endophytes to promote plant fitness could improve
the production of medicinal plants as well as their bioactive-derivate compounds in
medicinal plants (Jia et al. 2016).
Besides parasitism and antibiosis, Trichoderma spp. can manage to induce lipid
transferase proteins to confer defense against Phytophthora capsici (Bae et al. 2011).
Induction of systemic resistance was also evidenced by the activation of defenserelated enzymes on cucumber plants inoculated with a non-pathogenic strain of
Colletotrichum magna (Redman et al. 1999).
Timing is an important factor to ensure a successful biocontrol strategy. In this
trend, the order of arrival of endophytes and pathogens in Phaseolus lunatus was
analyzed (Adame-Álvarez et al. 2014). Interestingly, the antagonist effect of the
endophytes on the pathogen was only successful when the endophyte colonization occurs first; otherwise, endophyte inoculation after pathogen infection rather
facilitates disease development (Adame-Álvarez et al. 2014).
As mentioned earlier, fungal endophytes can trigger ISR in the host. The mechanisms involved in this response are analogous to those imposed by mycorrhizal fungi,
involving the SA and JA signaling pathways (Jung et al. 2012; Pozo and AzcónAguilar 2007). In a previous study, it has been demonstrated that JA is necessary
for the biocontrol response in tomato triggered by the infection of a non-pathogenic
F. solani strain (Kavroulakis et al. 2007). In this system, F. solani can elicit ISR
against Septoria lycopersici by expression of pathogenesis-related (PR) genes in
roots. In agreement with the effects reported for bacterial endophytes, it has been
demonstrated that ethylene, as well as JA, is required for ISR triggered by fungal
endophytes (Kavroulakis et al. 2007). Nevertheless, a recent study has demonstrated
that inoculation with an endophytic Fusarium strain can trigger the systemic response
independently of JA, SA, and ethylene (Constantin et al. 2019).
As exposed above, the interactions between grasses and fungi belonging to
the Clavicipitaceous group constitute protective mutualisms. The effect of the
endophyte-infected grasses (E+) on the dynamic population of the insect pest has been
extensively compared with the non-endophyte infected grasses (E−). For example,
Lolium multiflorum-E. occultans interaction reduces the aphid population by 64%
and the nymph by 81%, consequently, the fecundity of the aphid populations is
strongly affected (Bastias et al. 2017b).
Complementary to the protection conferred by the alkaloids production, recent
studies on the endophyte-grass interactions has demonstrated the ability of the endophyte to enhance the plant immunity through mechanisms involving the JA-mediated
response, by the promotion of JA-signaling and repression of SA-signaling defenses
(Bastias et al. 2017a). Besides, the interaction between Lolium pernenne-Epichlöe