[show abstract][hide abstract] ABSTRACT: Tomato (Solanum lycopersicum) is susceptible to gray mold (Botrytis cinerea). Quantitative resistance to B. cinerea was previously identified in a wild relative, S. neorickii G1.1601. The 122 F3 families derived from a cross between the susceptible S. lycopersicum cv. Moneymaker and the partially resistant S. neorickii G1.1601 were tested for susceptibility to B. cinerea using a stem bioassay. Three putative quantitative trait loci (pQTL) were detected: pQTL3 and pQTL9 reducing lesion growth (LG) and pQTL4 reducing disease incidence (DI). For each pQTL, a putative homologous locus was identified recently in another wild tomato relative, S. habrochaites LYC4. pQTL3 was confirmed by assessing disease resistance in BC3S1 and BC3S2 progenies of S. neorickii G1.1601. pQTL4 was not statistically confirmed but the presence of the S. neorickii resistance allele reduced DI in all three tested populations. The reduction in LG of pQTL9 was not confirmed but rather, this locus conferred a reduced DI, similar to observations in the QTL study using S. habrochaites. The results are discussed in relation to other disease resistance loci identified in studies with other wild tomato relatives.
[show abstract][hide abstract] ABSTRACT: We functionally analysed two Nep1-like protein (NLP) genes from Botrytis elliptica (a specialized pathogen of lily), encoding proteins homologous to the necrosis and ethylene-inducing protein (NEP1) from Fusarium oxysporum. Single gene replacement mutants were made for BeNEP1 and BeNEP2, providing the first example of transformation and successful targeted mutagenesis in this fungus. The virulence of both mutants on lily leaves was not affected. BeNEP1 and BeNEP2 were individually expressed in the yeast Pichia pastoris, and the necrosis-inducing activity was tested by infiltration of both proteins into leaves of several monocots and eudicots. Necrotic symptoms developed on the eudicots tobacco, Nicotiana benthamiana and Arabidopsis thaliana, and cell death was induced in tomato cell suspensions. No necrotic symptoms developed on leaves of the monocots rice, maize and lily. These results support the hypothesis that the necrosis-inducing activity of NLPs is limited to eudicots. We conclude that NLPs are not essential virulence factors and they do not function as host-selective toxins for B. elliptica.
[show abstract][hide abstract] ABSTRACT: Evolutionary patterns of sequence divergence were analyzed in genes from the fungal genus Botrytis (Ascomycota), encoding phytotoxic proteins homologous to a necrosis and ethylene-inducing protein from Fusarium oxysporum. Fragments of two paralogous genes (designated NEP1 and NEP2) were amplified from all known Botrytis species and sequenced. NEP1 sequences of two Botrytis species contain premature stop codons, indicating that they may be non-functional. Both paralogs of all species encode proteins with a remarkably similar predicted secondary structure, however, they contain different types of post-translational modification motifs, which are conserved across the genus. While both NEP genes are, overall, under purifying selection, we identified a number of amino acids under positive selection based on inference using maximum likelihood models. Positively selected amino acids in NEP1 were not under selection in corresponding positions in NEP2. The biological significance of positively selected residues and the role of NEP proteins in pathogenesis remain to be resolved.
[show abstract][hide abstract] ABSTRACT: The objective of this study was to assess the genetic diversity and to infer the mode of reproduction of Botrytis elliptica and B. tulipae in the Netherlands. First, three molecular typing methods were compared for their ability to differentiate isolates of B. tulipae, B. elliptica, and B. cinerea. The methods compared were multilocus sequencing, restriction analysis of the ribosomal intergenic spacer (IGS) region, and amplified fragment length polymorphism (AFLP) analysis. AFLP fingerprinting provided the most efficient method to differentiate isolates within each Botrytis species and therefore this method was used for population analyses of B. elliptica and B. tulipae. Isolates of both species were sampled during successive growing seasons in experimental field plots in Lisse and other locations in the Netherlands. Among 174 B. elliptica isolates, 105 genotypes could be discriminated and 87 genotypes were found only once, reflecting high genotypic variation. Clonal genotypes were found only within growing seasons and in one location. Linkage disequilibrium analyses indicated that between 9.4% and 19.3% of the loci in clone-corrected samples were linked. The multilocus association index provided no evidence for random mating. We conclude that sexual recombination occurs in the B. elliptica population. Among the 170 B. tulipae isolates, 25 genotypes could be discriminated and four genotypes were found only once, reflecting a low genotypic variation. Clonal genotypes were frequently found in different growing seasons and different locations. Linkage disequilibrium analyses indicated that between 25.2% and 48.6% of the loci in clone-corrected samples were linked. We conclude that the B. tulipae population is mainly clonal with some recombination.
European Journal of Plant Pathology 01/2007; · 1.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: BOTRYTIS cinerea Pers:Fr (teleomorph: Botryotina fuckeliana (de Bary) Whetzel) is a necrotrophic pathogenic fungus with an exceptionally wide host range of at least 235 species. Modern hybrid tomato (Solanum lycopersicum) cultivars are susceptible to B. cinerea although there are cultivars with some quantitative resistance. In a screening Solanum habrochaites LYC4 showed a good level of resistance. To study the genetics behind this resistance, an F2 population (n=174) of the cross between a susceptible genotype S. lycopersicum cv. Moneymaker and S. habrochaites LYC4 was developed. Initially, two QTLs for resistance to B. cinerea were identified (QTL1 and QTL2). During the confirmation of these two QTLs in segregating BC2S1 families, a third QTL (QTL3) was identified from which the effect could only be observed in absence of QTL2. A set of QTL specific CAPS makers was developed as a tool for marker assisted selection (MAS). Using this set of markers, one BC2S1 line was selected which was homozygous for both QTL 1 and QTL3. BC2S2 offspring of this line was tested for resistance to B. cinerea in a greenhouse trail. In the selected BC2S2 offspring only 15% of the infections were successfully established (disease incidence). This is significantly less than the susceptible control S. lycopersicum (disease incidence 70%); a commercial cultivar known as fairly resistant still had a disease incidence of 50%. This result shows that the QTLs from S. habrochaites LYC4 offer good perspectives for breeding B. cinerea resistant tomato cultivars.
[show abstract][hide abstract] ABSTRACT: Botrytis cinerea is a ubiquitous filamentous fungal pathogen of a wide range of plant species. The fungus is able to infect all aerial parts of its host plants to a certain extent. Infection may cause enormous damage both during plant growth and in the post-harvest phase (during cold storage or transport). B. cinerea is a major cause of economic loss in the production chain of cut flowers, bulb flowers and pot plants. Molecular-genetic studies performed over the past decade have provided a wealth of novel insights into the infection mechanisms utilised by the pathogen. Fungal genes were identified that are important for successful infection by B. cinerea. Such knowledge provides perspectives for designing novel, rational plant protection strategies that effectively counteract important fungal virulence factors. In this review I will divide the infection process into different stages and discuss the role of various fungal enzymes and metabolites in the individual stages. Finally some perspectives are addressed for novel control strategies that may reduce and/or delay the damage inflicted by B. cinerea infection
[show abstract][hide abstract] ABSTRACT: The genus Botrytis contains necrotrophic plant pathogens that have a wide host range (B. cinerea) or are specialized on a single host species, e.g. B. elliptica on lily. In this study, it was found that B. elliptica-induced cell death of lily displays hallmark features of animal programmed cell death or apoptosis including cytoplasmic shrinkage, nuclear DNA fragmentation and the accumulation of NO as well as H2O2. A pharmacological approach showed that B. elliptica-induced cell death could be modulated by serine and cysteine protease inhibitors including one caspase inhibitor. Blocking phosphatase activity stimulated cell death and concomitant lesion formation, suggesting that B. elliptica-induced cell death is mediated by kinase/phosphatase pathways. Blocking Ca2+ influx restricted cell death. Blocking steps of sphingolipid biosynthesis delayed lily cell death for several days. B. elliptica culture filtrate (CF) was able to induce lily cell death by means of secreted proteins. Induction of cell death is necessary and sufficient for pathogenicity and host specialization because prior infiltration of B. elliptica CF enabled subsequent infection of lily by the otherwise incompatible pathogens B. cinerea and B. tulipae. The secreted B. elliptica proteins also induced cell death in some but not all Arabidopsis accessions and mutants. Arabidopsis accessions that respond to infiltration of B. elliptica CF also display cell death symptoms upon inoculation with B. elliptica conidia.
[show abstract][hide abstract] ABSTRACT: Catalase mediates the enzymatic breakdown of hydrogen peroxide to water and molecular oxygen. During the infection of broad bean (Vicia faba) byBotrytis cinereathe release of hydrogen peroxide by fungal oxidase activity was proposed to facilitate penetration by the pathogen. Catalase activity might play a role in protecting the fungus against the damaging effects of hydrogen peroxide.A cDNA clone encoding catalase was isolated from a library ofBotrytis cinerea. Southern blot analysis of genomic DNA indicated the presence of a single copy gene, denoted ascatA. The cDNA clone encoded a protein, CAT-A, of 480 amino acids showing 56–65% similarity to fungal catalases. Detailed analysis of sequence homologies between other fungal catalases enabled grouping of catalases according to their cellular location. CAT-A ofB. cinerearesembled most closely the peroxisomal catalases. Northern blot analysis showed induction of the gene by H2O2in vitro. In planta, nocatAexpression could be detected by northern blot analysis, whereas a constitutively expressed β-tubulin mRNA ofB. cinereawas detectable and symptom development on the inoculated leaves was very clear. However, a catalase genecat1of tomato appeared to be induced from the time of fungal penetration onwards, suggesting that H2O2is produced during the interaction.
Physiological and Molecular Plant Pathology 50 (1997) 1-15. 01/1997;
[show abstract][hide abstract] ABSTRACT: Kerssies, A., Bosker-van Zessen, A. I., Wagemakers, C. A. M., and van Kan, J. A. L. 1997. Variation in pathogenicity and DNA polymorphism among Botrytis cinerea isolates sampled inside and outside a glasshouse. Plant Dis. 81:781-786. Colonies of Botrytis cinerea were obtained from spore samplers placed inside and outside a glasshouse with a rose crop. Pure cultures were made from five colonies collected on one sam- pling date every month throughout the year. These isolates were tested for germination on water agar and for pathogenicity on gerbera and rose petals. The germination rate of the conidia on water agar varied between 60 and 99%. Pathogenicity of the isolates on gerbera and rose flow- ers ranged from 14 to 166% relative to reference isolate Bc16 and varied among isolates col- lected on the same day as much as among isolates collected in different months. The patho- genicity of the isolates on rose flowers was overall higher than on gerbera flowers. Random amplified polymorphic DNA (RAPD) analysis was performed on 30 selected isolates with dif- ferent relative pathogenicity, collected both inside and outside the glasshouse. Almost all of the isolates were genetically different. No correlation was found among pathogenicity, sampling time, sampling place, and RAPD patterns. Results are further evidence for the statement that B. cinerea inoculum in glasshouses continuously originates from many different sources in their vicinity.