Clonostachys rosea is a mycoparasitic fungal species being an efficient biocontrol agent against ... more Clonostachys rosea is a mycoparasitic fungal species being an efficient biocontrol agent against many plant diseases. During mycoparasitic interactions one of the most crucial steps is the hydrolysis of the prey's fungal cell wall, which mainly consists of glucans, glycoproteins and chitin. Chitinases are hydrolytic enzymes responsible for chitin degradation and it is suggested that they play an important role in fungal-fungal interactions. Fungal chitinases belong exclusively to glycoside hydrolases (GH) family 18. These GH18 proteins are categorized into 3 distinct phylogenetic groups (A, B and C), subdivided into several subgroups. In this study we identified 14 GH18 genes in the C. rosea genome, which is remarkably lower compared with the high numbers found in mycoparasitic Trichoderma species. Phylogenetic analysis revealed that C. rosea contains 8 genes in group A, 2 genes in group B, 2 genes in group C, 1 gene encoding a putative ENGase and the ech37 gene which is of bact...
Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pat... more Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pathogens. However, possible adverse effects of this fungus on arbuscular mycorrhizal fungi might be a drawback in its use in plant protection. The objective of the present work was to examine the interaction between Glomus intraradices and T. harzianum in soil. The use of a compartmented growth system with root-free soil compartments enabled us to study fungal interactions without the interfering effects of roots. Growth of the fungi was monitored by measuring hyphal length and population densities, while specific fatty acid signatures were used as indicators of living fungal biomass. Hyphal 33P transport and beta-glucuronidase (GUS) activity were used to monitor activity of G. intraradices and a GUS-transformed strain of T. harzianum, respectively. As growth and metabolism of T. harzianum are requirements for antagonism, the impact of wheat bran, added as an organic nutrient source for T....
In six field experiments, seed treatment with Clonostachys rosea (IK726) significantly reduced di... more In six field experiments, seed treatment with Clonostachys rosea (IK726) significantly reduced disease caused by Fusarium culmorum. IK726 was active against the pathogen at average soil temperatures at sowing ranging from 6.2 to 12 °C. Both in the field experiments and in growth chamber experiments conducted in sand, dried and stored conidia of IK726 controlled F. culmorum as effectively as
Page 1. Biocontrol Science and Technology (2002) 12, 427ą441 Survival of Conidia of Clonostachys ... more Page 1. Biocontrol Science and Technology (2002) 12, 427ą441 Survival of Conidia of Clonostachys rosea on Stored Barley Seeds and Their Biocontrol EYcacy Against Seed-borne Bipolaris sorokiniana BIRGIT JENSEN, INGE MB KNUDSEN and DAN FUNCK JENSEN ...
Universally primed PCR (UP-PCR) fingerprinting combined with UP-PCR product cross hybridization, ... more Universally primed PCR (UP-PCR) fingerprinting combined with UP-PCR product cross hybridization, and ITS1 ribotyping were used to study the genetic relatedness of strains of Trichoderma and Gliocladium for two purposes: (1) to evaluate the ability of the methods to discriminate closely related strains and as tools to group strains which is necessary to facilitate; (2) identification of markers for development of specific detection assays for selected strains. Included among the strains were one T. harzianum, two T. virens, and one G. roseum that had been selected previously for their antagonistic ability against soil-borne phytopathogens. Similarity among strains, found by cross dot blot hybridization using UP-PCR amplification products, was used to group them into 15 genetic entities. ITS1 ribotyping of the strains was performed by digestion of the PCR amplified rDNA spacer region and electrophoresis of the products. The differences obtained from ribotyping as well as the differences in mobility of the intact spacer region were used for grouping of the strains. The UP-PCR hybridization groups and the ITS1 based groups proved to be consistent, but the resolution of the UP-PCR based approach was superior. The results demonstrate that the combination of UP-PCR and ribotyping can aid in clarifying species distinction in Trichoderma and Gliocladium and has the potential to become a valuable tool for studies of diversity and genetic structure of populations of these fungi. Furthermore, identification of single strains by the specific UP-PCR fingerprint seems feasible.
ABSTRACT Fifty-one isolates representing the four Botrytis spp. associated with onion neck rot we... more ABSTRACT Fifty-one isolates representing the four Botrytis spp. associated with onion neck rot were clustered by unweighted pair group method with arithmetic mean based on universal-primed polymerase chain reaction (UP-PCR) fingerprints. Bootstrap analysis of the consensus phenogram clearly demonstrated five strong clusters among the four Botrytis spp.: B. cinerea (C), B. squamosa (S), B. byssoidea (B), and B. aclada (AI and AII). Subdivision of the 30 B. aclada isolates, AI (14) and AII (16), from Europe, Egypt, North America, and Japan was further supported by restriction analysis of the internal transcribed spacer of the ribosomal genes and spore size measurements. Gene diversities (H) among AI and AII isolates were very low (0.007 and 0.043, respectively). A likelihood ratio chi-square test (G(2)) of Nei's coefficient of genetic differentiation (G(ST)) showed that both B. aclada subgroups, AI and AII, were significantly different from B. byssoidea (P < 0.001), and that B. aclada subgroups AI and AII were significantly different from each other (P < 0.001). No UP-PCR alleles were shared by AI and B. byssoidea isolates, whereas 10 and 12 alleles were shared by AI:AII and AII:B. byssoidea, respectively. The hypothesis that AII may be a hybrid between AI and B. byssoidea is discussed.
Many carrots are discarded during post harvest cold storage due to development of fungal infectio... more Many carrots are discarded during post harvest cold storage due to development of fungal infections, caused by, e.g., Mycocentrospora acerina (liquorice rot). We compared the susceptibility of carrots grown under conventional and organic agricultural practices. In one year, organically cultivated carrots showed 3× to 7× more symptoms than conventionally cultivated, when studying naturally occurring disease at 4 and 6 months, respectively. On the other hand, we have developed a bioassay for infection studies of M. acerina on carrots and observed that organic roots were more susceptible after one month of storage than conventional ones, but no differences were apparent after four or six months storage. Levels of polyacetylenes (falcarinol, falcarindiol and falcarindiol-3-acetate) did not change, whereas the isocoumarin phytoalexin (6-methoxymellein) accumulated in infected tissue as well as in healthy tissue opposite the infection. The proteomes of carrot and M. acerina were characterized, the intensity of 33 plant protein spots was significantly changed in infected roots including up regulation of defence and stress response proteins but also a decrease of proteins involved in energy metabolism. This combined metabolic and proteomic study indicates that roots respond to fungal infection through altered metabolism: simultaneous induction of 6-methoxymellein and synthesis of defence related proteins.
Clonostachys rosea is a mycoparasitic fungal species being an efficient biocontrol agent against ... more Clonostachys rosea is a mycoparasitic fungal species being an efficient biocontrol agent against many plant diseases. During mycoparasitic interactions one of the most crucial steps is the hydrolysis of the prey's fungal cell wall, which mainly consists of glucans, glycoproteins and chitin. Chitinases are hydrolytic enzymes responsible for chitin degradation and it is suggested that they play an important role in fungal-fungal interactions. Fungal chitinases belong exclusively to glycoside hydrolases (GH) family 18. These GH18 proteins are categorized into 3 distinct phylogenetic groups (A, B and C), subdivided into several subgroups. In this study we identified 14 GH18 genes in the C. rosea genome, which is remarkably lower compared with the high numbers found in mycoparasitic Trichoderma species. Phylogenetic analysis revealed that C. rosea contains 8 genes in group A, 2 genes in group B, 2 genes in group C, 1 gene encoding a putative ENGase and the ech37 gene which is of bact...
Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pat... more Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pathogens. However, possible adverse effects of this fungus on arbuscular mycorrhizal fungi might be a drawback in its use in plant protection. The objective of the present work was to examine the interaction between Glomus intraradices and T. harzianum in soil. The use of a compartmented growth system with root-free soil compartments enabled us to study fungal interactions without the interfering effects of roots. Growth of the fungi was monitored by measuring hyphal length and population densities, while specific fatty acid signatures were used as indicators of living fungal biomass. Hyphal 33P transport and beta-glucuronidase (GUS) activity were used to monitor activity of G. intraradices and a GUS-transformed strain of T. harzianum, respectively. As growth and metabolism of T. harzianum are requirements for antagonism, the impact of wheat bran, added as an organic nutrient source for T....
In six field experiments, seed treatment with Clonostachys rosea (IK726) significantly reduced di... more In six field experiments, seed treatment with Clonostachys rosea (IK726) significantly reduced disease caused by Fusarium culmorum. IK726 was active against the pathogen at average soil temperatures at sowing ranging from 6.2 to 12 °C. Both in the field experiments and in growth chamber experiments conducted in sand, dried and stored conidia of IK726 controlled F. culmorum as effectively as
Page 1. Biocontrol Science and Technology (2002) 12, 427ą441 Survival of Conidia of Clonostachys ... more Page 1. Biocontrol Science and Technology (2002) 12, 427ą441 Survival of Conidia of Clonostachys rosea on Stored Barley Seeds and Their Biocontrol EYcacy Against Seed-borne Bipolaris sorokiniana BIRGIT JENSEN, INGE MB KNUDSEN and DAN FUNCK JENSEN ...
Universally primed PCR (UP-PCR) fingerprinting combined with UP-PCR product cross hybridization, ... more Universally primed PCR (UP-PCR) fingerprinting combined with UP-PCR product cross hybridization, and ITS1 ribotyping were used to study the genetic relatedness of strains of Trichoderma and Gliocladium for two purposes: (1) to evaluate the ability of the methods to discriminate closely related strains and as tools to group strains which is necessary to facilitate; (2) identification of markers for development of specific detection assays for selected strains. Included among the strains were one T. harzianum, two T. virens, and one G. roseum that had been selected previously for their antagonistic ability against soil-borne phytopathogens. Similarity among strains, found by cross dot blot hybridization using UP-PCR amplification products, was used to group them into 15 genetic entities. ITS1 ribotyping of the strains was performed by digestion of the PCR amplified rDNA spacer region and electrophoresis of the products. The differences obtained from ribotyping as well as the differences in mobility of the intact spacer region were used for grouping of the strains. The UP-PCR hybridization groups and the ITS1 based groups proved to be consistent, but the resolution of the UP-PCR based approach was superior. The results demonstrate that the combination of UP-PCR and ribotyping can aid in clarifying species distinction in Trichoderma and Gliocladium and has the potential to become a valuable tool for studies of diversity and genetic structure of populations of these fungi. Furthermore, identification of single strains by the specific UP-PCR fingerprint seems feasible.
ABSTRACT Fifty-one isolates representing the four Botrytis spp. associated with onion neck rot we... more ABSTRACT Fifty-one isolates representing the four Botrytis spp. associated with onion neck rot were clustered by unweighted pair group method with arithmetic mean based on universal-primed polymerase chain reaction (UP-PCR) fingerprints. Bootstrap analysis of the consensus phenogram clearly demonstrated five strong clusters among the four Botrytis spp.: B. cinerea (C), B. squamosa (S), B. byssoidea (B), and B. aclada (AI and AII). Subdivision of the 30 B. aclada isolates, AI (14) and AII (16), from Europe, Egypt, North America, and Japan was further supported by restriction analysis of the internal transcribed spacer of the ribosomal genes and spore size measurements. Gene diversities (H) among AI and AII isolates were very low (0.007 and 0.043, respectively). A likelihood ratio chi-square test (G(2)) of Nei's coefficient of genetic differentiation (G(ST)) showed that both B. aclada subgroups, AI and AII, were significantly different from B. byssoidea (P < 0.001), and that B. aclada subgroups AI and AII were significantly different from each other (P < 0.001). No UP-PCR alleles were shared by AI and B. byssoidea isolates, whereas 10 and 12 alleles were shared by AI:AII and AII:B. byssoidea, respectively. The hypothesis that AII may be a hybrid between AI and B. byssoidea is discussed.
Many carrots are discarded during post harvest cold storage due to development of fungal infectio... more Many carrots are discarded during post harvest cold storage due to development of fungal infections, caused by, e.g., Mycocentrospora acerina (liquorice rot). We compared the susceptibility of carrots grown under conventional and organic agricultural practices. In one year, organically cultivated carrots showed 3× to 7× more symptoms than conventionally cultivated, when studying naturally occurring disease at 4 and 6 months, respectively. On the other hand, we have developed a bioassay for infection studies of M. acerina on carrots and observed that organic roots were more susceptible after one month of storage than conventional ones, but no differences were apparent after four or six months storage. Levels of polyacetylenes (falcarinol, falcarindiol and falcarindiol-3-acetate) did not change, whereas the isocoumarin phytoalexin (6-methoxymellein) accumulated in infected tissue as well as in healthy tissue opposite the infection. The proteomes of carrot and M. acerina were characterized, the intensity of 33 plant protein spots was significantly changed in infected roots including up regulation of defence and stress response proteins but also a decrease of proteins involved in energy metabolism. This combined metabolic and proteomic study indicates that roots respond to fungal infection through altered metabolism: simultaneous induction of 6-methoxymellein and synthesis of defence related proteins.
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