The spread of aggressive fungal pathogens into previously non-endemic regions is a major threat t... more The spread of aggressive fungal pathogens into previously non-endemic regions is a major threat to plant health and food security. Analyses of the spatial and genetic structure of plant pathogens offer valuable insights into their origin, dispersal mechanisms and evolution, and have been useful to develop successful disease management strategies. Here, we elucidated the genetic diversity, population structure, and demographic history of worldwide invasion of the ascomycete Verticillium dahliae, a soil-borne pathogen, using a global collection of 1100 isolates from multiple plant hosts and countries. Seven well-differentiated genetic clusters were revealed through discriminant analysis of principal components (DAPC), but no strong associations between these clusters and host/geographic origin of isolates were found. Analyses of clonal evolutionary relationships among multilocus genotypes with the eBURST algorithm and analyses of genetic distances revealed that genetic clusters repres...
SUMMARY The yeast Metschnikowia pulcherrima (Pitt) M.W. Miller, isolate 320, showing antagonistic... more SUMMARY The yeast Metschnikowia pulcherrima (Pitt) M.W. Miller, isolate 320, showing antagonistic activity against Botrytis cinerea, causal agent of storage rot of table grapes, strawberry and kiwifruit, was transformed with the yeast-enhanced green fluorescent protein (yEGFP) gene, using plasmid pACT2.yEGFP and the lithium ac- etate protocol. Colonies expressing yEGFP were select- ed using an epifluorescence microscope. The antagonis- tic activity
In previous trials the flavonoid quercetin proved to be effective in reducing Penicillium expansu... more In previous trials the flavonoid quercetin proved to be effective in reducing Penicillium expansum infections and patulin accumulation in apples. Since quercetin resulted more effective in in vivo than in in vitro trials, a possible role of this substance in enhancing host resistance was hypothesized. To verify this hypothesis, a cDNA library of genes differentially expressed in response to quercetin application was constructed by using the suppression subtractive hybridization (SSH) approach. A total of 89 unique sequences were obtained. By homology search and functional analysis the identified sequences were putatively categorized as belonging to "metabolism", "subcellular localization" and "protein with binding functions or cofactor requirement" classes. Similarity was also found with genes coding proteins whose role in defence mechanisms is still unknown.
RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of org... more RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including phytopathogenic fungi. In such fungi, RNAi has been induced by expressing hairpin RNAs delivered through plasmids, sequences integrated in fungal or plant genomes, or by RNAi generated in planta by a plant virus infection. All these approaches have some drawbacks ranging from instability of hairpin constructs in fungal cells to difficulties in preparing and handling transgenic plants to silence homologous sequences in fungi grown on these plants. Here we show that RNAi can be expressed in the phytopathogenic fungus Colletotrichum acutatum (strain C71) by virus-induced gene silencing (VIGS) without a plant intermediate, but by using the direct infection of a recombinant virus vector based on the plant virus, tobacco mosaic virus (TMV). We provide evidence that a wild-type isolate of TMV is able to enter C71 cells grown in liquid medium, replicate, and persist therein. Wi...
Background The fungus Pochonia chlamydosporia plays multiple, useful roles in the rhizosphere of ... more Background The fungus Pochonia chlamydosporia plays multiple, useful roles in the rhizosphere of plants, acting as saprophyte, hyperparasite of nematode eggs or endophyte and growth promoter. Objectives Given the potentials of P. chlamydosporia in plant growth promotion, the changes induced in tomato roots have been investigated by transcriptome analysis, in order to i) identify patterns of differentially expressed genes in the roots and ii) to investigate the most important changes induced during the endophytic phase. Methods RNA was extracted from roots of tomato plants, cv Regina, growing in soil either inoculated or not with the fungus. Root transcriptome was investigated and compared in a dual approach through a next generation sequencing (NGS) method. Sequencing and mapping 46 million single-end 51 bp reads of high quality score (Q40 =1 error/104 bases) against the tomato transcriptome (ftp://ftp.solgenomics.net) allowed the identification of 9112 tomato genes differentially e...
To collect information on the incidence of Verticilli-um wilt of olive in Apulia (southern Italy)... more To collect information on the incidence of Verticilli-um wilt of olive in Apulia (southern Italy), about 6,000 woody samples from 1,390 young and old olive or-chards were analysed. Moreover, 565 soil samples from commercial orchards and nurseries located all over Apulia region were tested for the presence of V. dahliae microsclerotia. Verticillium wilt was found in the 18% of the surveyed orchards, mainly in seaside-located in-tensive plantations, which are usually intercropped with vegetables susceptible to V. dahliae. However, the dis-ease was also found in young plantations established on soil which resulted free of the pathogen, thus indicating a role of the propagating material in the spread of the disease. On the whole, 16% of surveyed fields and 50% of nurseries were contaminated by the pathogen. Over-all, the results suggest that preventive diagnostic tests of leafy cuttings, soil and soil mix are mandatory to obtain V. dahliae-free propagative material to limit the spread o...
The spread of aggressive fungal pathogens into previously non-endemic regions is a major threat t... more The spread of aggressive fungal pathogens into previously non-endemic regions is a major threat to plant health and food security. Analyses of the spatial and genetic structure of plant pathogens offer valuable insights into their origin, dispersal mechanisms and evolution, and have been useful to develop successful disease management strategies. Here, we elucidated the genetic diversity, population structure, and demographic history of worldwide invasion of the ascomycete Verticillium dahliae, a soil-borne pathogen, using a global collection of 1100 isolates from multiple plant hosts and countries. Seven well-differentiated genetic clusters were revealed through discriminant analysis of principal components (DAPC), but no strong associations between these clusters and host/geographic origin of isolates were found. Analyses of clonal evolutionary relationships among multilocus genotypes with the eBURST algorithm and analyses of genetic distances revealed that genetic clusters repres...
SUMMARY The yeast Metschnikowia pulcherrima (Pitt) M.W. Miller, isolate 320, showing antagonistic... more SUMMARY The yeast Metschnikowia pulcherrima (Pitt) M.W. Miller, isolate 320, showing antagonistic activity against Botrytis cinerea, causal agent of storage rot of table grapes, strawberry and kiwifruit, was transformed with the yeast-enhanced green fluorescent protein (yEGFP) gene, using plasmid pACT2.yEGFP and the lithium ac- etate protocol. Colonies expressing yEGFP were select- ed using an epifluorescence microscope. The antagonis- tic activity
In previous trials the flavonoid quercetin proved to be effective in reducing Penicillium expansu... more In previous trials the flavonoid quercetin proved to be effective in reducing Penicillium expansum infections and patulin accumulation in apples. Since quercetin resulted more effective in in vivo than in in vitro trials, a possible role of this substance in enhancing host resistance was hypothesized. To verify this hypothesis, a cDNA library of genes differentially expressed in response to quercetin application was constructed by using the suppression subtractive hybridization (SSH) approach. A total of 89 unique sequences were obtained. By homology search and functional analysis the identified sequences were putatively categorized as belonging to "metabolism", "subcellular localization" and "protein with binding functions or cofactor requirement" classes. Similarity was also found with genes coding proteins whose role in defence mechanisms is still unknown.
RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of org... more RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including phytopathogenic fungi. In such fungi, RNAi has been induced by expressing hairpin RNAs delivered through plasmids, sequences integrated in fungal or plant genomes, or by RNAi generated in planta by a plant virus infection. All these approaches have some drawbacks ranging from instability of hairpin constructs in fungal cells to difficulties in preparing and handling transgenic plants to silence homologous sequences in fungi grown on these plants. Here we show that RNAi can be expressed in the phytopathogenic fungus Colletotrichum acutatum (strain C71) by virus-induced gene silencing (VIGS) without a plant intermediate, but by using the direct infection of a recombinant virus vector based on the plant virus, tobacco mosaic virus (TMV). We provide evidence that a wild-type isolate of TMV is able to enter C71 cells grown in liquid medium, replicate, and persist therein. Wi...
Background The fungus Pochonia chlamydosporia plays multiple, useful roles in the rhizosphere of ... more Background The fungus Pochonia chlamydosporia plays multiple, useful roles in the rhizosphere of plants, acting as saprophyte, hyperparasite of nematode eggs or endophyte and growth promoter. Objectives Given the potentials of P. chlamydosporia in plant growth promotion, the changes induced in tomato roots have been investigated by transcriptome analysis, in order to i) identify patterns of differentially expressed genes in the roots and ii) to investigate the most important changes induced during the endophytic phase. Methods RNA was extracted from roots of tomato plants, cv Regina, growing in soil either inoculated or not with the fungus. Root transcriptome was investigated and compared in a dual approach through a next generation sequencing (NGS) method. Sequencing and mapping 46 million single-end 51 bp reads of high quality score (Q40 =1 error/104 bases) against the tomato transcriptome (ftp://ftp.solgenomics.net) allowed the identification of 9112 tomato genes differentially e...
To collect information on the incidence of Verticilli-um wilt of olive in Apulia (southern Italy)... more To collect information on the incidence of Verticilli-um wilt of olive in Apulia (southern Italy), about 6,000 woody samples from 1,390 young and old olive or-chards were analysed. Moreover, 565 soil samples from commercial orchards and nurseries located all over Apulia region were tested for the presence of V. dahliae microsclerotia. Verticillium wilt was found in the 18% of the surveyed orchards, mainly in seaside-located in-tensive plantations, which are usually intercropped with vegetables susceptible to V. dahliae. However, the dis-ease was also found in young plantations established on soil which resulted free of the pathogen, thus indicating a role of the propagating material in the spread of the disease. On the whole, 16% of surveyed fields and 50% of nurseries were contaminated by the pathogen. Over-all, the results suggest that preventive diagnostic tests of leafy cuttings, soil and soil mix are mandatory to obtain V. dahliae-free propagative material to limit the spread o...
La recrudescenza della lebbra dell’olivo osservata in Puglia negli ultimi anni, ascrivibile al fa... more La recrudescenza della lebbra dell’olivo osservata in Puglia negli ultimi anni, ascrivibile al favorevole andamento meteorologico stagionale, alla riduzione delle cure colturali e al mutato quadro eziologico e biologico della malattia, è stata oggetto di specifiche indagini sull’epidemiologia della malattia e sulla protezione. In particolare, sono stati raccolti dati sulla densità di inoculo di Colletotrichum spp. presente sulle drupe e sulla diffusione delle infezioni latenti nei frutti. Inoltre, sono state svolte prove sull’attività di prodotti a base di QoI applicati in diverse fasi fenologiche (ripresa vegetativa, pre-fioritura, post-allegagione, invaiatura). I risultati ottenuti indicano una buona efficacia di pyraclostrobin da solo o in miscela con rame, e della miscela trifloxystrobin+tebuconazolo sia nel contenimento della popolazione del patogeno, sia nella riduzione delle infezioni latenti delle drupe, rispetto a prodotti tradizionali a base di rame. Parole chiave: antracnosi, Colletotrichum spp., pyraclostrobin, trifloxystrobin, tebuconazolo
Uploads
Papers by Franco Nigro
densità di inoculo di Colletotrichum spp. presente sulle drupe e sulla diffusione delle infezioni latenti nei frutti. Inoltre, sono state svolte prove sull’attività di prodotti a base di QoI applicati
in diverse fasi fenologiche (ripresa vegetativa, pre-fioritura, post-allegagione, invaiatura). I risultati ottenuti indicano una buona efficacia di pyraclostrobin da solo o in miscela con rame,
e della miscela trifloxystrobin+tebuconazolo sia nel contenimento della popolazione del patogeno, sia nella riduzione delle infezioni latenti delle drupe, rispetto a prodotti tradizionali a base di rame.
Parole chiave: antracnosi, Colletotrichum spp., pyraclostrobin, trifloxystrobin, tebuconazolo