Biocontrol by Trichoderma has been studied mainly with selected isolates of T. harzianum, T. atroviride and T. asperellum, which are members of sections Pachybasium and Trichoderma. In contrast, species from section L...Biocontrol by Trichoderma has been studied mainly with selected isolates of T. harzianum, T. atroviride and T. asperellum, which are members of sections Pachybasium and Trichoderma. In contrast, species from section Longibrachiatum have only rarely been studied. On the other hand, one taxon from this section-Hypocrea jecorina (anamorph: Trichoderma reesei)-has been widely used for the production of cellulolytic and hemicellulolytic enzymes and recombinant proteins. As far as Trichoderma is concerned, molecular genetic methods and tools are most advanced in H. jecorina, and its genome has recently been fully sequenced, thus making this taxon a model organism for the genus. Here we will demonstrate that H. jecorina is able to antagonize plant pathogenic fungi in plate confrontation tests, and can protect tomato and cucumber plants against Pythium ultimum blight. Using this as a model case, we made use of available H. jecorina mutants to investigate (a) whether carbon catabolite repression via the Cre1-regulator protein has an impact on biocontrol, and (b) whether cellulase gene expression is necessary for biocontrol of P. ultimum. In the first case, plate confrontation tests and in planta experiments yielded opposite results, i.e. while a Cre1 mutant was more active in antagonization of fungi on plates, the survival rates of P. ultimum-inoculated cucumber plants was lower than with the H. jecorina wild-type strain. Mutants of H. jecorina, unable to form cellulases, were still able to antagonize fungi on plates and provided similar protection of tomatos against P. ultimum as the wild type, indicating that the pronounced biocontrol ability of H. jecorina against fungi with cellulose-containing cell-walls is not due to its high cellulolytic activity. A strain disrupted in the light-modulator gene envoy (Schmoll et al., ms submitted) exhibited in planta biocontrol activity strongly exceeding that of the wild-type strain, thereby providing a first link between Trichoderma biocontrol and light. In view of the numerous other metabolic and regulatory mutants of H. jecorina available, we suggest that this fungus should increasingly be used in basic studies on the biochemistry and genetics of biocontrol.展开更多
Safe strain identification and species recognition is an important issue for Trichoderma and Hypocrea, because members of the genus are economically important producers of industrial enzymes and antibiotics, have appl...Safe strain identification and species recognition is an important issue for Trichoderma and Hypocrea, because members of the genus are economically important producers of industrial enzymes and antibiotics, have application as biocontrol agents against plant pathogens, whereas some have become known as opportunistic pathogens of immunocompromised mammals and humans. However, classical approaches based on the use of morphological and phenetic characters have been difficult to apply, due to the plasticity of characters and the discordance of morphological and molecular evolution. The application of the genealogical concordance and phylogenetic species concept (GCPSC) has made is an attractive alternative to morphological species recognition, but has not been stringently applied to Hypocrea/Trichoderma. In this review, I shall explain the tools needed and strategy of this concept, and I will present examples where it has been recently used by us and others to confirm existing taxa and to detect new species in various clades and sections of Trichoderma. In addition, the present state of a global survey of biodiversity of Trichoderma and Hypocrea will be presented, and reviewed in relation to biogeography and the mode of speciation of this genus.展开更多
With increased imports of foreign microbes either as commercial biocontrol produ cts or for the purposes of research, there is potentially an increased threat to indigenous beneficial microflora. In the present study,...With increased imports of foreign microbes either as commercial biocontrol produ cts or for the purposes of research, there is potentially an increased threat to indigenous beneficial microflora. In the present study, indigenous species of t he fungal genus Hypocrea/Trichoderma are being used as a model system to d etermine the impact of foreign microbes on the native microflora of New Zealand. In order to protect such microflora, one has to first be aware of what is curre ntly present and what sites, if any, are most vulnerable. A preliminary survey f or the presence and diversity of species of Hypocrea/Trichoderma is curren tly underway in New Zealand and samples are being assessed from forest soils, ag ricultural soils, orchards, garden soils, sclerotia of various plant pathogens a nd pasture land. To date 238 isolates have been identified using both morphologi cal characters and DNA sequence data from the ITS regions of the ribosomal gene cluster (ITS1 & ITS2) and, in some instances, sequence of the elongation facto r gene (EF1-α) . Isolates were found to represent 16 known species plus three s pec ies as yet undescribed. In forest soils T. harzianum /T. inhamatum (31%) and T. viride (29%) followed by T. fertile (13%), were clearly th e most abundant species and the remaining five species found in forests (T. a troviride, T. koningii, T. aureoviride, H. cf. flavovirens anamorph and one u nknown) each accounting for <8% of the total. Dominance by the species T. h arzianum/inhamatum is consistent with studies done in South-East Asia, a mid -E uropean primeval floodplain-forest and Moscow. In contrast, when isolations wer e conducted with a bias for biocontrol capabilities it was found that the species T. atroviride (29%), T. koningii (17 %), T. harzianum (1 5%) and T. viride (12%) dominated respectively. This survey is currently on go ing in New Zealand. Future studies will monitor indigenous species and strains f ollowing inoculation of specific microbes to assess the impact of the introduced microbe on the natural ecosystem.展开更多
本研究从曼地亚红豆杉(Taxus x media)树皮内表皮分离得到一株产紫杉醇的内生真菌Z58,通过高效液相色谱法、质谱法和核磁共振波谱法对其紫杉醇提取物进行了分析.结果表明,内生真菌Z58的紫杉醇提取物具有和紫杉醇标准品相近的色谱特征峰...本研究从曼地亚红豆杉(Taxus x media)树皮内表皮分离得到一株产紫杉醇的内生真菌Z58,通过高效液相色谱法、质谱法和核磁共振波谱法对其紫杉醇提取物进行了分析.结果表明,内生真菌Z58的紫杉醇提取物具有和紫杉醇标准品相近的色谱特征峰,其保留时间为10.2 min;也与紫杉醇标准品具有相同的质谱特征峰((M+Na)+=876)和1H-NMR谱带.并通过形态学特征分析和18S rDNA序列分析,将内生真菌Z58初步鉴定为肉座菌属(Hypocrea sp.)真菌.肉座菌Z58的紫杉醇产量约为2.5～3.0μg/g(紫杉醇/菌丝干重),是一株具有潜在应用价值的产紫杉醇内生真菌.展开更多
文摘Biocontrol by Trichoderma has been studied mainly with selected isolates of T. harzianum, T. atroviride and T. asperellum, which are members of sections Pachybasium and Trichoderma. In contrast, species from section Longibrachiatum have only rarely been studied. On the other hand, one taxon from this section-Hypocrea jecorina (anamorph: Trichoderma reesei)-has been widely used for the production of cellulolytic and hemicellulolytic enzymes and recombinant proteins. As far as Trichoderma is concerned, molecular genetic methods and tools are most advanced in H. jecorina, and its genome has recently been fully sequenced, thus making this taxon a model organism for the genus. Here we will demonstrate that H. jecorina is able to antagonize plant pathogenic fungi in plate confrontation tests, and can protect tomato and cucumber plants against Pythium ultimum blight. Using this as a model case, we made use of available H. jecorina mutants to investigate (a) whether carbon catabolite repression via the Cre1-regulator protein has an impact on biocontrol, and (b) whether cellulase gene expression is necessary for biocontrol of P. ultimum. In the first case, plate confrontation tests and in planta experiments yielded opposite results, i.e. while a Cre1 mutant was more active in antagonization of fungi on plates, the survival rates of P. ultimum-inoculated cucumber plants was lower than with the H. jecorina wild-type strain. Mutants of H. jecorina, unable to form cellulases, were still able to antagonize fungi on plates and provided similar protection of tomatos against P. ultimum as the wild type, indicating that the pronounced biocontrol ability of H. jecorina against fungi with cellulose-containing cell-walls is not due to its high cellulolytic activity. A strain disrupted in the light-modulator gene envoy (Schmoll et al., ms submitted) exhibited in planta biocontrol activity strongly exceeding that of the wild-type strain, thereby providing a first link between Trichoderma biocontrol and light. In view of the numerous other metabolic and regulatory mutants of H. jecorina available, we suggest that this fungus should increasingly be used in basic studies on the biochemistry and genetics of biocontrol.
文摘Safe strain identification and species recognition is an important issue for Trichoderma and Hypocrea, because members of the genus are economically important producers of industrial enzymes and antibiotics, have application as biocontrol agents against plant pathogens, whereas some have become known as opportunistic pathogens of immunocompromised mammals and humans. However, classical approaches based on the use of morphological and phenetic characters have been difficult to apply, due to the plasticity of characters and the discordance of morphological and molecular evolution. The application of the genealogical concordance and phylogenetic species concept (GCPSC) has made is an attractive alternative to morphological species recognition, but has not been stringently applied to Hypocrea/Trichoderma. In this review, I shall explain the tools needed and strategy of this concept, and I will present examples where it has been recently used by us and others to confirm existing taxa and to detect new species in various clades and sections of Trichoderma. In addition, the present state of a global survey of biodiversity of Trichoderma and Hypocrea will be presented, and reviewed in relation to biogeography and the mode of speciation of this genus.
文摘With increased imports of foreign microbes either as commercial biocontrol produ cts or for the purposes of research, there is potentially an increased threat to indigenous beneficial microflora. In the present study, indigenous species of t he fungal genus Hypocrea/Trichoderma are being used as a model system to d etermine the impact of foreign microbes on the native microflora of New Zealand. In order to protect such microflora, one has to first be aware of what is curre ntly present and what sites, if any, are most vulnerable. A preliminary survey f or the presence and diversity of species of Hypocrea/Trichoderma is curren tly underway in New Zealand and samples are being assessed from forest soils, ag ricultural soils, orchards, garden soils, sclerotia of various plant pathogens a nd pasture land. To date 238 isolates have been identified using both morphologi cal characters and DNA sequence data from the ITS regions of the ribosomal gene cluster (ITS1 & ITS2) and, in some instances, sequence of the elongation facto r gene (EF1-α) . Isolates were found to represent 16 known species plus three s pec ies as yet undescribed. In forest soils T. harzianum /T. inhamatum (31%) and T. viride (29%) followed by T. fertile (13%), were clearly th e most abundant species and the remaining five species found in forests (T. a troviride, T. koningii, T. aureoviride, H. cf. flavovirens anamorph and one u nknown) each accounting for <8% of the total. Dominance by the species T. h arzianum/inhamatum is consistent with studies done in South-East Asia, a mid -E uropean primeval floodplain-forest and Moscow. In contrast, when isolations wer e conducted with a bias for biocontrol capabilities it was found that the species T. atroviride (29%), T. koningii (17 %), T. harzianum (1 5%) and T. viride (12%) dominated respectively. This survey is currently on go ing in New Zealand. Future studies will monitor indigenous species and strains f ollowing inoculation of specific microbes to assess the impact of the introduced microbe on the natural ecosystem.
