the ribosome, and in some cases followed by secondary modifications, peptabiotics,
and epidithiodioxopiperazines are some kind of NRPs from Trichoderma [1].
Species of the genus Trichoderma are prolific producers of peptaibols which
may contain 7–20 amino acids and characteristically have an acylated N-terminal
group, C-terminal amino alcohol, and a high content of 2-amino-isobutyric acid
(Aib) [16, 63]. The first identified peptaibol of this class is known as alamethicin
from T. viride [64]. This peptaibol has antimicrobial activity against gram-positive
bacteria and also is a potent elicitor of volatile compounds in lima bean
(Phaseolus lunatus). Other peptaibols are suzukacillin A, trichorovins,
trichodecenins I and II and trichocellins from T. viride, trichokonins V–VIII from
T. koningii, trichobrachin A I–IV and B I–IV from T. longibrachiatum, atroviridins
from T. atroviride, etc. [16, 65–68]. Other characterized peptaibiotics are 14
12-residue trichocryptins B, 12 11-residue trichocryptins A, 19 11-residue
trichobrevins A and B, 6 10-residue trichoferins, and 17 8-residue trichocompactins
[69]. The trichogins A from T. longibrachiatum and the trichodecenins from T. viride
are an example of lipopeptaibols [65, 70].
Viterbo and coworkers [71] described that T. virens Gv29-8 produces at least three
lengths of peptaibols (11, 14, and 18 residues long). It was found that synthetic 18mer
peptaibols, TvBI (Ac-UGAVUQUAUSLUPLUUQV-OH) and TvBII (AcUGALUQUAUSLUPLUUQV-OH) as T. virens, elicited cucumber (Cucumis sativus)
defense responses that were effective against the leaf pathogen Pseudomonas syringae
pv. lachrymans. Similarly, the peptaibols 11mer and 14 mer also from T. virens seem to
be involved in the activation of defense responses in A. thaliana via SA [12]. Clearly,
this information is evidence that NRPs play key roles in the Trichoderma-plant
chemical communication to stimulate plant immunity.
On the other hand, the low molecular weight compound 1-octen-3-ol, a typical
oxylipin from fungi, activated jasmonic acid/ethylene-dependent and wound-dependent defense genes such as AOS, HPL, and PDF 1.2 (PLANT DEFENSIN1.2) and
enhanced resistance against B. cinerea in A. thaliana [53]. Plant defense activation
by Trichoderma also includes the induction and accumulation of phytoalexins.
Camalexin is the main phytoalexin of A. thaliana that can be stimulated after
infection with bacterial and fungal plant pathogens [23]. A number of aldehydes
possess the ability to react with cysteine to form the corresponding thiazolidine
carboxylic acid [72]. It has been reported that the synthesis of camalexin may
proceed through the condensation of ICAld with L-cysteine followed by a twostep oxidation and decarboxylation [73]. Interestingly, a study showed that T. virens
and T. atroviride or the application of ICAld increased camalexin accumulation in A.
thaliana seedlings [23].
Nitric oxide (NO) is a key molecule for regulation of plant defense responses, and
it is rapidly generated after plant-microorganism interaction [74]. There is evidence
that T. asperelloides suppresses the NO generation stimulated by the plant pathogen
fungus Fusarium oxysporum in Arabidopsis thaliana roots, most likely to prevent
toxic effects caused for this reactive species [75]. Supporting this reasoning is the
finding that T. harzianum T-22 enhanced the antioxidative mechanisms involving
higher activity of ascorbate, glutathione, superoxide dismutase catalase, and
12 Interactions of Trichoderma with Plants, Insects, and Plant Pathogen. . .
273
and epidithiodioxopiperazines are some kind of NRPs from Trichoderma [1].
Species of the genus Trichoderma are prolific producers of peptaibols which
may contain 7–20 amino acids and characteristically have an acylated N-terminal
group, C-terminal amino alcohol, and a high content of 2-amino-isobutyric acid
(Aib) [16, 63]. The first identified peptaibol of this class is known as alamethicin
from T. viride [64]. This peptaibol has antimicrobial activity against gram-positive
bacteria and also is a potent elicitor of volatile compounds in lima bean
(Phaseolus lunatus). Other peptaibols are suzukacillin A, trichorovins,
trichodecenins I and II and trichocellins from T. viride, trichokonins V–VIII from
T. koningii, trichobrachin A I–IV and B I–IV from T. longibrachiatum, atroviridins
from T. atroviride, etc. [16, 65–68]. Other characterized peptaibiotics are 14
12-residue trichocryptins B, 12 11-residue trichocryptins A, 19 11-residue
trichobrevins A and B, 6 10-residue trichoferins, and 17 8-residue trichocompactins
[69]. The trichogins A from T. longibrachiatum and the trichodecenins from T. viride
are an example of lipopeptaibols [65, 70].
Viterbo and coworkers [71] described that T. virens Gv29-8 produces at least three
lengths of peptaibols (11, 14, and 18 residues long). It was found that synthetic 18mer
peptaibols, TvBI (Ac-UGAVUQUAUSLUPLUUQV-OH) and TvBII (AcUGALUQUAUSLUPLUUQV-OH) as T. virens, elicited cucumber (Cucumis sativus)
defense responses that were effective against the leaf pathogen Pseudomonas syringae
pv. lachrymans. Similarly, the peptaibols 11mer and 14 mer also from T. virens seem to
be involved in the activation of defense responses in A. thaliana via SA [12]. Clearly,
this information is evidence that NRPs play key roles in the Trichoderma-plant
chemical communication to stimulate plant immunity.
On the other hand, the low molecular weight compound 1-octen-3-ol, a typical
oxylipin from fungi, activated jasmonic acid/ethylene-dependent and wound-dependent defense genes such as AOS, HPL, and PDF 1.2 (PLANT DEFENSIN1.2) and
enhanced resistance against B. cinerea in A. thaliana [53]. Plant defense activation
by Trichoderma also includes the induction and accumulation of phytoalexins.
Camalexin is the main phytoalexin of A. thaliana that can be stimulated after
infection with bacterial and fungal plant pathogens [23]. A number of aldehydes
possess the ability to react with cysteine to form the corresponding thiazolidine
carboxylic acid [72]. It has been reported that the synthesis of camalexin may
proceed through the condensation of ICAld with L-cysteine followed by a twostep oxidation and decarboxylation [73]. Interestingly, a study showed that T. virens
and T. atroviride or the application of ICAld increased camalexin accumulation in A.
thaliana seedlings [23].
Nitric oxide (NO) is a key molecule for regulation of plant defense responses, and
it is rapidly generated after plant-microorganism interaction [74]. There is evidence
that T. asperelloides suppresses the NO generation stimulated by the plant pathogen
fungus Fusarium oxysporum in Arabidopsis thaliana roots, most likely to prevent
toxic effects caused for this reactive species [75]. Supporting this reasoning is the
finding that T. harzianum T-22 enhanced the antioxidative mechanisms involving
higher activity of ascorbate, glutathione, superoxide dismutase catalase, and
12 Interactions of Trichoderma with Plants, Insects, and Plant Pathogen. . .
273