The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Maria Aragona - One of the best experts on this subject based on the ideXlab platform.
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The genome assembly of the fungal pathogen Pyrenochaeta lycopersici from Single-Molecule Real-Time sequencing sheds new light on its biological complexity.
PloS one, 2018Co-Authors: Alessandra Dal Molin, Alessandro Infantino, Andrea Minio, Francesca Griggio, Massimo Delledonne, Maria AragonaAbstract:The first draft genome sequencing of the non-model fungal pathogen Pyrenochaeta lycopersici showed an expansion of gene families associated with heterokaryon incompatibility and lacking of mating-type genes, providing insights into the genetic basis of this "imperfect" fungus which lost the ability to produce the sexual stage. However, due to the Illumina short-read technology, the draft genome was too fragmented to allow a comprehensive characterization of the genome, especially of the repetitive sequence fraction. In this work, the sequencing of another P. lycopersici isolate using long-read Single Molecule Real-Time sequencing technology was performed with the aim of obtaining a gapless genome. Indeed, a gapless genome assembly of 62.7 Mb was obtained, with a fraction of repetitive sequences representing 30% of the total bases. The gene content of the two P. lycopersici isolates was very similar, and the large difference in genome size (about 8 Mb) might be attributable to the high fraction of repetitive sequences detected for the new sequenced isolate. The role of repetitive elements, including transposable elements, in modulating virulence effectors is well established in fungal plant pathogens. Moreover, transposable elements are of fundamental importance in creating and re-modelling genes, especially in imperfect fungi. Their abundance in P. lycopersici, together with the large expansion of heterokaryon incompatibility genes in both sequenced isolates, suggest the presence of possible mechanisms alternative to gene re-assorting mediated by sexual recombination. A quite large fraction (~9%) of repetitive elements in P. lycopersici, has no homology with known classes, strengthening this hypothesis. The availability of a gapless genome of P. lycopersici allowed the in-depth analysis of its genome content, by annotating functional genes and TEs. This goal will be an important resource for shedding light on the evolution of the reproductive and pathogenic behaviour of this soilborne pathogen and the onset of a possible speciation within this species.
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Genetic transformation of the tomato pathogen Pyrenochaeta lycopersici allowed gene knockout using a split-marker approach
Current Genetics, 2015Co-Authors: Maria Aragona, Maria Teresa ValenteAbstract:Pyrenochaeta lycopersici , as other soil-transmitted fungal pathogens, generally received little attention compared to the pathogens affecting the aerial parts of the plants, although causing stunt and important fruit yield reduction of agronomic relevant crops. The scope of this study was to develop a system allowing to investigate the functional role of P. lycopersici genes putatively involved in the corky root rot of tomato. A genetic transformation system based on a split-marker approach was developed and tested to knock out a P. lycopersici gene encoding for a lytic polysaccharide monooxygenase ( Plegl1 ) induced during the disease development. The regions flanking Plegl1 gene were fused with the overlapping parts of hygromycin marker gene, to favour homologous recombination. We were able to obtain four mutants not expressing the Plegl1 gene though, when tested on a susceptible tomato cultivar, Plegl1 mutants showed unaltered virulence, compared with the wild-type strain. The strategy illustrated in the present work demonstrated for the first time that homologous recombination occurs in P. lycopersici . Moreover, a transformation system mediated by Agrobacterium tumefaciens was established and stable genetic transformants have been obtained. The transformation systems developed represent important tools for investigating both the role of genes putatively involved in P. lycopersici interaction with host plant and the function of other physiological traits which emerged to be genetically expanded from the recent genome sequencing of this fungus.
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Genetic structure of Italian populations of Pyrenochaeta lycopersici, the causal agent of corky root rot of tomato
Plant Pathology, 2014Co-Authors: Alessandro Infantino, Maria Aragona, Nicoletta Pucci, S. De Felice, Domenico RauAbstract:Pyrenochaeta lycopersici is the causal agent of corky root rot, which is a serious disease worldwide that attacks the roots of tomato. A total of 139 isolates were sampled from eight locations in Italy and Israel and assigned to two molecular types (type 1 and type 2) based on internal transcribed spacer (ITS) sequences. These isolates were genotyped using amplified fragment length polymorphisms (AFLPs) to decipher the population structure. Based on this population structure analysis, three groups of P. lycopersici were identified. One group correlated to ITS type 1, while the other two correlated to ITS type 2. AMOVA indicated high genetic divergence (FST = 0� 40) between the Italian types 1 and 2. These data support the view that the two ITS types represent significant evolutionary entities, although there might be incomplete lineage sorting present. Some isolates of different ITS type were observed to have very similar multilocus AFLP profiles, and some genotypes were intermediate between the two ITS types. This suggests that parasexual hybridization between the two types has had a significant role in shaping the population structure of P. lycopersici. Finally, the average divergence among the populations within the ITS types was very high (FSC = 0� 710, P < 10 � 5 ), probably
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De novo genome assembly of the soil-borne fungus and tomato pathogen Pyrenochaeta lycopersici
BMC Genomics, 2014Co-Authors: Maria Aragona, Alessandro Infantino, Maria Teresa Valente, Andrea Minio, Alberto Ferrarini, Paolo Bagnaresi, Luigi Orrù, Paola Tononi, Gianpiero Zamperin, Giampiero ValèAbstract:Background Pyrenochaeta lycopersici is a soil-dwelling ascomycete pathogen that causes corky root rot disease in tomato ( Solanum lycopersicum ) and other Solanaceous crops, reducing fruit yields by up to 75%. Fungal pathogens that infect roots receive less attention than those infecting the aerial parts of crops despite their significant impact on plant growth and fruit production. Results We assembled a 54.9Mb P. lycopersici draft genome sequence based on Illumina short reads, and annotated approximately 17,000 genes. The P. lycopersici genome is closely related to hemibiotrophs and necrotrophs, in agreement with the phenotypic characteristics of the fungus and its lifestyle. Several gene families related to host–pathogen interactions are strongly represented, including those responsible for nutrient absorption, the detoxification of fungicides and plant cell wall degradation, the latter confirming that much of the genome is devoted to the pathogenic activity of the fungus. We did not find a MAT gene, which is consistent with the classification of P. lycopersici as an imperfect fungus, but we observed a significant expansion of the gene families associated with heterokaryon incompatibility (HI). Conclusions The P. lycopersici draft genome sequence provided insight into the molecular and genetic basis of the fungal lifestyle, characterizing previously unknown pathogenic behaviors and defining strategies that allow this asexual fungus to increase genetic diversity and to acquire new pathogenic traits.
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Molecular and functional characterization of an endoglucanase in the phytopathogenic fungus Pyrenochaeta lycopersici
Current Genetics, 2011Co-Authors: Maria Teresa Valente, Alessandro Infantino, Maria AragonaAbstract:Many fungal plant pathogens secrete an array of cell wall degrading enzymes mainly involved in the pathogenesis. In this work, a cDNA clone encoding an extracellular endo-1,4-β-glucanase (named PlEGL1) from the causal agent of the Corky Root Rot of tomato, Pyrenochaeta lycopersici , was isolated and characterized, in order to understand its putative role in the pathogenesis and its mechanism of action. Multiple alignment of the deduced amino acidic sequence shows a high homology with other endoglucanases from different phytopathogenic fungi and detects a well-defined conserved domain of the Glycosyl Hydrolase family 61 (GH61). In vitro, Plegl1 gene transcription is correlated to a cellulolytic activity of the fungus, regulated, in its turn, by the presence of sugar and/or cellulose in the culture medium. In the infected plants, expression level of Plegl1 is positively correlated to the development of the disease. PlEGL1 was heterologously expressed in Escherichia coli and the recombinant protein was purified and tested for its cellulolytic ability, showing a very weak activity, in agreement with all the endoglucanases belonging to GH61 family. The finding in this paper will provide the basis for further determination of biochemical properties of the PlEGL1 protein and its possible involvement in the host–pathogen interaction.
Sophia K. Ekengren - One of the best experts on this subject based on the ideXlab platform.
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The corky root rot pathogen, Pyrenochaeta lycopersici manipulates tomato roots with molecules secreted early during their interaction
Acta Agriculturae Scandinavica Section B - Soil & Plant Science, 2012Co-Authors: Pierre-henri Clergeot, Claudia Rivetti, Mollah Md. Hamiduzzaman, Sophia K. EkengrenAbstract:Corky root rot is a ubiquitous soil-borne disease of tomato caused by the pathogen Pyrenochaeta lycopersici. This filamentous fungus is found on the roots of many crops and can persist in the soil ...
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The Corky Root Rot Pathogen Pyrenochaeta lycopersici Secretes a Proteinaceous Inducer of Cell Death Affecting Host Plants Differentially
Phytopathology, 2012Co-Authors: Pierre-henri Clergeot, Herwig Schüler, Ejvind Mørtz, Maja Brus, Simina Vintila, Sophia K. EkengrenAbstract:Clergeot, P.-H., Schuler, H., Mortz, E., Brus, M., Vintila, S., and Ekengren, S. 2012. The corky root rot pathogen Pyrenochaeta lycopersici secretes a proteinaceous inducer of cell death affecting host plants differentially. Phytopathology 102:878-891. Pathogenic isolates of Pyrenochaeta lycopersici, the causal agent of corky root rot of tomato, secrete cell death in tomato 1 (CDiT1), a homodimeric protein of 35 kDa inducing cell death after infiltration into the leaf apoplast of tomato. CDiT1 was purified by fast protein liquid chromatography, characterized by mass spectrometry and cDNA cloning. Its activity was confirmed after infiltration of an affinity-purified recombinant fusion of the protein with a C-terminal polyhistidine tag. CDiT1 is highly expressed during tomato root infection compared with axenic culture, and has a putative ortholog in other pathogenic Pleosporales species producing proteinaceous toxins that contribute to virulence. Infiltration of CDiT1 into leaves of other plants susceptible to P. lycopersici revealed that the protein affects them differentially. All varieties of cultivated tomato (Solanum lycopersicum) tested were more sensitive to CDiT1 than those of currant tomato (S. pimpinellifolium). Root infection assays showed that varieties of currant tomato are also significantly less prone to intracellular colonization of their root cells by hyphae of P. lycopersici than varieties of cultivated tomato. Therefore, secretion of this novel type of inducer of cell death during penetration of the fungus inside root cells might favor infection of host species that are highly sensitive to this molecule.
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Cutting the Gordian knot: taking a stab at corky root rot of tomato
Plant Biotechnology, 2008Co-Authors: Sophia K. EkengrenAbstract:Corky root rot (CRR) is an escalating plant disease of tomato (Solanum esculentum), caused by a soil-borne fungus, Pyrenochaeta lycopersici. During the last two decades there have almost been no progress in the understanding of the molecular mechanisms promoting infection and plant susceptibility. As there are no CRR-resistant lines of cultivated tomato on the market and no other known means for plant protection, a deeper molecular knowledge about the infection process is urgently needed. We have therefore outlined an efficient strategy to search for corky root rot-resistance genes in wild tomato. In addition, we are investigating the genetic determinants for infection and virulence of the fungal pathogen, P. lycopersici. In this review we summarize the quite limited molecular knowledge about the pathogen and the disease, and discuss the possibilities to overcome previous technical obstacles in this new era of molecular biology.
Birgitta Ramert - One of the best experts on this subject based on the ideXlab platform.
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Potential use of biocontrol agents for control of Pyrenochaeta lycopersici in tomato crops
Acta Agriculturae Scandinavica Section B - Plant Soil Science, 2009Co-Authors: Ana Varela, Birgitta Ramert, Anna MårtenssonAbstract:Corky root is a severe disease caused by the fungus Pyrenochaeta lycopersici Schneider et Gerlach that affects tomato crops worldwide in both field and greenhouse (Punithalingam & Holliday, 1973; E...
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Management of corky root disease of tomato in participation with organic tomato growers.
Crop Protection, 2009Co-Authors: M.k. Hasna, Anna Mårtensson, P. Persson, E. Ögren, Birgitta RamertAbstract:Abstract Corky root disease of tomato, caused by the soil-borne fungus Pyrenochaeta lycopersici , is a common and serious problem for organic tomato production. This paper addresses the possibility of developing a management strategy for corky root disease in participation with organic tomato growers in Sweden. The participatory research group consisted of nine organic tomato growers from central Sweden, two extension workers and two researchers. Regular meetings were held so that growers, extension workers and researchers could exchange knowledge on corky root disease management. A number of research issues were identified during group discussions: use of mulch, break crop, grafted tomato plants, composts, composted Pyrenochaeta -infested soil, fungivorous nematodes and commercially available bio-control agents based on Trichoderma , Streptomyces and Gliocladium in corky root disease control. The issues were investigated in on-farm experiments and experiments at a research station. The outcomes of the research work were presented in the group in subsequent meetings and assessed in joint discussions. The results from the study showed that a compost with low NH 4 -N concentration and high Ca concentration reduced corky root disease severity in greenhouse experiments at the research station. However, although the potential of other measures such as use of fungivorous nematodes and commercially available bio-control agents was demonstrated, these measures need further improvement to be adopted in commercial growing conditions.
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Effects of fungivorous nematodes on corky root disease of tomato grown in compost-amended soil
Acta Agriculturae Scandinavica Section B - Plant Soil Science, 2008Co-Authors: M.k. Hasna, Jan Lagerlöf, Birgitta RamertAbstract:Abstract The effect of fungivorous nematodes, Aphelenchus avenae and Aphelenchoides spp., against corky root disease of tomato caused by Pyrenochaeta lycopersici was investigated. Three different greenhouse trials were conducted using soil naturally infested with P. lycopersici, alone or mixed with four different types of compost consisting of green manure, garden waste and horse manure (20% compost by volume). The fungivorous nematodes were propagated in cultures of the fungus Pochonia bulbillosa and inoculated (3 or 23 nematodes ml−1 substrate) into the soil and soil-compost mixtures one day after transplanting of tomato seedlings. Greenhouse experiments were terminated after ten weeks and disease was measured from infected roots after harvesting. Aphelenchus avenae significantly reduced the disease severity when added to infested soil without compost in all experiments. Aphelenchoides spp. did not suppress the disease either in the presence or absence of compost. Among the composts tested, only a garde...
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Use of composts to manage corky root disease in organic tomato production
Annals of Applied Biology, 2007Co-Authors: M.k. Hasna, Anna Mårtensson, P. Persson, Birgitta RamertAbstract:Corky root disease of tomato caused by Pyrenochaeta lycopersici is an economically important disease in organic tomato production. This study aimed to evaluate the effects of various composts consisting of green manure, garden waste and horse manure against corky root disease through bioassay under greenhouse conditions, where soil naturally infested with P. lycopersici was used as a root substrate. The various composts were mixed at a rate of 20% (v/v) with the infested soil. Disease severity (measured as infected roots) in the unamended soil was compared with that in the soil–compost mixtures. One of the composts made from garden waste significantly reduced the disease, whereas horse manure compost significantly stimulated it. Lower concentrations of NH4-N and total carbon and a higher concentration of Ca in the substrate were correlated with lower level of corky root disease. Addition of green manure or garden waste compost to the infested soil increased total microbial activity or population density of copiotrophic bacteria and actinomycetes, respectively. However, increased microbial activity or microbial population in soil–compost mixtures was not associated with a reduction in corky root disease severity in the present study.
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Food attraction and population growth of fungivorous nematodes with different fungi
Annals of Applied Biology, 2007Co-Authors: M.k. Hasna, Jan Lagerlöf, V. Insunza, Birgitta RamertAbstract:Food attraction of the fungivorous nematodes Aphelenchus avenae and Aphelenchoides spp. to seven fungal species (Pyrenochaeta lycopersici, Botrytis cinerea, Rhizoctonia solani strains AG 3 and AG 2-1, Verticillium dahliae, Pochonia bulbillosa, Mortierella hyalina and Trichoderma harzianum) was determined on agar plates by counting the number of test nematodes present on the mycelium of each fungus 24 h after inoculation. Population growth of A. avenae and Aphelenchoides spp. on five of the seven fungi included in the attraction test (P. lycopersici, R. solani strain AG 3, V. dahliae, P. bulbillosa and T. harzianum) was also determined on agar plates by counting nematode numbers every week during a 6-week period. A. avenae and Aphelenchoides spp. were attracted to all the fungi tested. A. avenae was preferentially attracted to V. dahliae (P < 0.0001), and Aphelenchoides spp. did not show any preference except for low attraction to R. solani. A. avenae and Aphelenchoides spp. reproduced on all fungal species tested. After 6 weeks of incubation, the highest number of nematodes was found on P. lycopersici and P. bulbillosa, while the lowest number occurred on R. solani for A. avenae and on T. harzianum for Aphelenchoides spp. The suitability of a fungus as a host was not clearly related to the attraction to that fungus.
Maria Teresa Valente - One of the best experts on this subject based on the ideXlab platform.
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Genetic transformation of the tomato pathogen Pyrenochaeta lycopersici allowed gene knockout using a split-marker approach
Current Genetics, 2015Co-Authors: Maria Aragona, Maria Teresa ValenteAbstract:Pyrenochaeta lycopersici , as other soil-transmitted fungal pathogens, generally received little attention compared to the pathogens affecting the aerial parts of the plants, although causing stunt and important fruit yield reduction of agronomic relevant crops. The scope of this study was to develop a system allowing to investigate the functional role of P. lycopersici genes putatively involved in the corky root rot of tomato. A genetic transformation system based on a split-marker approach was developed and tested to knock out a P. lycopersici gene encoding for a lytic polysaccharide monooxygenase ( Plegl1 ) induced during the disease development. The regions flanking Plegl1 gene were fused with the overlapping parts of hygromycin marker gene, to favour homologous recombination. We were able to obtain four mutants not expressing the Plegl1 gene though, when tested on a susceptible tomato cultivar, Plegl1 mutants showed unaltered virulence, compared with the wild-type strain. The strategy illustrated in the present work demonstrated for the first time that homologous recombination occurs in P. lycopersici . Moreover, a transformation system mediated by Agrobacterium tumefaciens was established and stable genetic transformants have been obtained. The transformation systems developed represent important tools for investigating both the role of genes putatively involved in P. lycopersici interaction with host plant and the function of other physiological traits which emerged to be genetically expanded from the recent genome sequencing of this fungus.
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De novo genome assembly of the soil-borne fungus and tomato pathogen Pyrenochaeta lycopersici
BMC Genomics, 2014Co-Authors: Maria Aragona, Alessandro Infantino, Maria Teresa Valente, Andrea Minio, Alberto Ferrarini, Paolo Bagnaresi, Luigi Orrù, Paola Tononi, Gianpiero Zamperin, Giampiero ValèAbstract:Background Pyrenochaeta lycopersici is a soil-dwelling ascomycete pathogen that causes corky root rot disease in tomato ( Solanum lycopersicum ) and other Solanaceous crops, reducing fruit yields by up to 75%. Fungal pathogens that infect roots receive less attention than those infecting the aerial parts of crops despite their significant impact on plant growth and fruit production. Results We assembled a 54.9Mb P. lycopersici draft genome sequence based on Illumina short reads, and annotated approximately 17,000 genes. The P. lycopersici genome is closely related to hemibiotrophs and necrotrophs, in agreement with the phenotypic characteristics of the fungus and its lifestyle. Several gene families related to host–pathogen interactions are strongly represented, including those responsible for nutrient absorption, the detoxification of fungicides and plant cell wall degradation, the latter confirming that much of the genome is devoted to the pathogenic activity of the fungus. We did not find a MAT gene, which is consistent with the classification of P. lycopersici as an imperfect fungus, but we observed a significant expansion of the gene families associated with heterokaryon incompatibility (HI). Conclusions The P. lycopersici draft genome sequence provided insight into the molecular and genetic basis of the fungal lifestyle, characterizing previously unknown pathogenic behaviors and defining strategies that allow this asexual fungus to increase genetic diversity and to acquire new pathogenic traits.
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Molecular and functional characterization of an endoglucanase in the phytopathogenic fungus Pyrenochaeta lycopersici
Current Genetics, 2011Co-Authors: Maria Teresa Valente, Alessandro Infantino, Maria AragonaAbstract:Many fungal plant pathogens secrete an array of cell wall degrading enzymes mainly involved in the pathogenesis. In this work, a cDNA clone encoding an extracellular endo-1,4-β-glucanase (named PlEGL1) from the causal agent of the Corky Root Rot of tomato, Pyrenochaeta lycopersici , was isolated and characterized, in order to understand its putative role in the pathogenesis and its mechanism of action. Multiple alignment of the deduced amino acidic sequence shows a high homology with other endoglucanases from different phytopathogenic fungi and detects a well-defined conserved domain of the Glycosyl Hydrolase family 61 (GH61). In vitro, Plegl1 gene transcription is correlated to a cellulolytic activity of the fungus, regulated, in its turn, by the presence of sugar and/or cellulose in the culture medium. In the infected plants, expression level of Plegl1 is positively correlated to the development of the disease. PlEGL1 was heterologously expressed in Escherichia coli and the recombinant protein was purified and tested for its cellulolytic ability, showing a very weak activity, in agreement with all the endoglucanases belonging to GH61 family. The finding in this paper will provide the basis for further determination of biochemical properties of the PlEGL1 protein and its possible involvement in the host–pathogen interaction.
A. Infantino - One of the best experts on this subject based on the ideXlab platform.
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Comparative transcriptome profiling of the response to Pyrenochaeta lycopersici in resistant tomato cultivar Mogeor and its background genotype—susceptible Moneymaker
Functional & Integrative Genomics, 2019Co-Authors: Justyna Milc, A. Infantino, M. Aragona, Mt Valente, P. Bagnaresi, C. Biselli, E. Francia, N. PecchioniAbstract:Breeding for resistance is the most effective tool for controlling the corky root disease of tomato caused by Pyrenochaeta lycopersici . A comparative RNA-Seq-based transcriptomic analysis was conducted at 96 hpi (hours post infection) on two tomato cultivars: resistant Mogeor and its genetic background, and susceptible Moneymaker to investigate the differences in their transcriptomic response and identify the molecular bases of this plant-pathogen interaction. The number of differentially expressed genes (DEGs) identified was much higher in the susceptible than in the resistant genotype; however, the proportion of upregulated genes was higher in Mogeor (70.81%) than in Moneymaker (52.95%). Gene Ontology (GO) analysis enabled identification of 24 terms shared by the two cultivars that were consistent with responses to external stimulus, such as fungal infection. On the other hand, as many as 54 GO were enriched solely in Moneymaker, including terms related to defense response and cell wall metabolism. Our results could support the previous observations in other pathosystems, that susceptibility and resistance have overlapping signaling pathways and responses, suggesting that the P. lycopersici resistance gene pyl might be a recessive allele at a susceptibility locus, for which different candidate genes were identified based on the differences in induction or expression levels, observed between the resistant and susceptible genotype. MapMan analysis highlighted a complex hormone and transcription factors interplay where SA- and JA-induced pathways are modulated in a similar way in both genotypes and thus take part in a common response while the ethylene signaling pathways, induced mainly in susceptible Moneymaker, seem putatively contribute to its susceptibility.
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IDENTIFICATION OF TOMATO GENES DIFFERENTIALLY EXPRESSED DURING COMPATIBLE INTERACTION WITH Pyrenochaeta lycopersici
Journal of Plant Pathology, 2012Co-Authors: Justyna Anna Milc, A. Infantino, Nicola Pecchioni, M. AragonaAbstract:Breeding for resistance is the most effective tool for controlling the corky root disease of tomato caused by the fungus Pyrenochaeta lycopersici. However, little is known about the molecular bases of tomato-P. lycopersici interaction. In order to identify genes involved in the basal defence response activated in a susceptible cultivar and in disease symptom development, a set of cDNA-AFLP fragments derived from a profiling experiment was analysed. A total of 247 differentially expressed TDFs (transcript-derived fragments), identified as putative tomato genes, were characterized by similarity searches, and classified into 11 broad functional classes. Timings ranging between the early [48, 72 and 96 h post-infection (hpi)] and the late infection stages (20 and 27 dpi) were used. The changes of tomato root transcriptional profiles showed large differences in quantity and quality between the early and late stages of infection. Mechanisms of basal defence were most likely activated at early stages, when a gene coding for a receptor- like serine-threonine protein kinase and other genes of the signalling class were upregulated. At 20 dpi some of the mechanisms involved in defence were still activated, while at 27 dpi a general repression of gene expression was observed.
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study on the effect of starvation on genes expression in Pyrenochaeta lycopersici
International Symposium on Tomato Diseases, 2011Co-Authors: R Caiazzo, A. Infantino, E Lahoz, Aniello CrescenziAbstract:The pathogenicity of fungal pathogens is presumably dependent on genes that are expressed during infection; in order to test the hypothesis that starvation may mimic the condition of the initial stage of pathogenesis of Pyrenochaeta lycopersici on tomato and to better understand the mechanisms underlying the plant-pathogen interaction, an analysis with specific primer on cell wall degrading enzymes (CWDE) was made on the cDNA from starved and repleted fungal mycelia. Moreover, a cDNA library of differential expressed genes was created by means of a Rapid Suppression Subtractive Hybridization (RASH). Different expressions of genes were compared in the fungus growth on three different media: complete of nutrient, with low presence of nitrogen and with low presence of carbon. First results show a different pattern of expression of the polygalatturonase gene in the three different conditions of growth. Each amplified fragment could represent different molecular forms of the enzyme. Moreover, a differential expressed fragment was found in conditions of carbon starvation. The identity of the fragment was indicated by partial DNA sequencing as diacylglycerol O-acyltransferase. These results suggest that the low presence of carbon and nitrogen mimics the growth conditions of P. lycopersici in tomato plants but further analysis is necessary to have information about the protein involved in the signal of pathogenesis.
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Molecular strategies for the study of tomato-Pyrenochaeta lycopersici interaction
Acta Horticulturae, 2011Co-Authors: Mt Valente, Justyna Anna Milc, A. Infantino, M. Aragona, Nicola PecchioniAbstract:Tomato Corky Root (CRR) is a soil-borne disease, caused by the hemibiotrophic fungus Pyrenochaeta lycopersici that has recently become a disease of concern for many tomato-growing areas including major producers such as China, USA, Italy and Japan, both in greenhouses and in field. The molecular bases of interaction between tomato and P. lycopersici are still poorly understood and breeding for resistance remains the most effective tool for controlling the disease. We are currently investigating the mechanisms behind disease susceptibility and resistance against CRR using different molecular methods. A cDNA-AFLP based approach was employed for transcriptomic analysis of the fungus-plant interaction and led to the identification of fungal genes putatively involved in plant pathogenesis and in the disease symptoms development (Aragona and Infantino, 2008). Among several differentially transcribed fragments we focused on a P. lycopersici sequence having a high similarity with a beta-glucanase gene. We cloned the full genomic sequence of the endo-1,4 beta-glucanase gene isolated and analyzed its expression in susceptible and resistant tomato cultivars, with the final goal of identifying its role in the interaction with tomato. For expression analysis, a real-time PCR-based approach was conducted on tomato roots artificially infected with P. lycopersici at six different post-infection time points, compared to vegetative mycelium. The quantification of P. lycopersici biomass in relation with plant biomass was assessed and a correlation between expression of the glucanase gene and the progress of P. lycopersici during the time course of root infection was elucidated.
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First Report of Rhizopycnis vagum Associated with Tomato Roots in Italy
Plant disease, 2001Co-Authors: Angelo Porta-puglia, N. Pucci, G. Di Giambattista, A. InfantinoAbstract:Field surveys were made in several central and southern Italian tomato-growing areas for Pyrenochaeta lycopersici, the cause of corky root of tomato. In addition to P. lycopersici, a different fungus was frequently isolated from roots showing typical corky root symptoms, even after disinfestation of diseased roots with 0.1% (vol/wt) mercury chloride water solution for 1 min. The fungus was isolated from primary and secondary tomato roots in 8 of 21 fields visited. The isolates were grown on potato dextrose agar (PDA), with morphological features such as color and shape of mature conidia and pycnidia, type of conidiogenesis, presence of microsclerotia, and color of colony underside noted. Preliminary identification of the fungus was Rhizopycnis vagum Farr. To confirm the identification, the internal transcribed spacer (ITS) region of rDNA of one isolate (maintained at the ISPaVe collection at the authors' address and available on request as isolate ER 940) was amplified with two universal primers, ITS5 and...
