Ceratocystis cacaofunesta genome analysis reveals a large expansion of extracellular phosphatidylinositol-specific phospholipase-C genes (PI-PLC)

Volatile Organic Compounds from Ceratocystis cacaofunesta, a Causal Agent of Ceratocystis Wilt of Cacao

Fungi of the genus Ceratocystis are aggressive tree pathogens that cause serious diseases in several crops around the world. Ceratocystis wilt disease caused by C. cacaofunesta has been shown to be responsible for severe reductions in cacao production. In this study, headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used in combination with chemometric analysis for monitoring volatile organic compounds (VOCs) released from C. cacaofunesta. Low-molecular-weight esters, alcohols, ketones, and sulphur compounds were identified in the liquid broth. Monitoring the volatile profile over five days of fungal growth revealed that the concentrations of alcohol and esters were inversely proportional. Acetate esters were responsible for the intense fruity aroma of the C. cacaofunesta culture produced within the first hours after fungal inoculation, which decreased over time, and are likely associated with the attraction of insect vectors to maintain the life cycle of the pathogen. PCA revealed that 3-methylbutyl acetate was the metabolite with the highest factor loading for the separation of the VOC samples after 4 h of fungal growth, whereas ethanol and 3-methylbutan-1-ol had the highest factor loadings after 96 and 120 h. 3-Methylbutan-1-ol is a phytotoxic compound that is likely associated with host cell death since C. cacaofunesta is a necrotrophic fungus. Fungal VOCs play important roles in natural habitats, regulating developmental processes and intra- and interkingdom interactions. This is the first report on the volatiles released by C. cacaofunesta.

IMA Genome - F19 : A genome assembly and annotation guide to empower mycologists, including annotated draft genome sequences of Ceratocystis pirilliformis, Diaporthe australafricana, Fusarium ophioides, Paecilomyces lecythidis, and Sporothrix stenoceras

The pace at which Next Generation Sequence data is being produced continues to accelerate as technology improves. As a result, such data are increasingly becoming accessible to biologists outside of the field of bioinformatics. In contrast, access to training in the methods of genome assembly and annotation are not growing at a similar rate. In this issue, we report on a Genome Assembly Workshop for Mycologists that was held at the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria, South Africa and make available the 12 draft genome sequences emanating from the event. With the aim of making the process of genome assembly and annotation more accessible to biologists, we provide a step-by-step guide to both genome assembly and annotation, intended to encourage and empower mycologists to use genome data in their research.

Biocatalyst for the synthesis of natural flavouring compounds as food additives: Bridging the gap for a more sustainable industrial future

Biocatalysis entails the use of purified enzymes in the manufacturing of flavouring chemicals food industry as well as at the laboratory level. These biocatalysts can significantly accelerate organic chemical processes and improve product stereospecificity. The unique characteristics of biocatalyst helpful in synthesizing the environmentally friendly flavour and aroma compounds used as a food additive in foodstuffs. With methods like enzyme engineering on biotechnological interventions the efficient tuning of produce will fulfil the needs of food industry. This review summarizes the biosynthesis of different flavour and aroma component through microbial catalysts and using advanced techniques which are available for enzyme improvement. Also pointing out their benefits and drawbacks for specific technological processes necessary for successful industrial application of biocatalysts. The article covers the market scenario, cost economics, environmental safety and regulatory framework for the production of food flavoured chemicals by the bioprocess engineering.

Unidirectional mating-type switching is underpinned by a conserved MAT1 locus architecture

Unidirectional mating-type switching is a form of homothallic reproduction known only in a small number of filamentous ascomycetes. Their ascospores can give rise to either self-sterile isolates that require compatible partners for subsequent sexual reproduction, or self-fertile individuals capable of completing this process in isolation. The limited studies previously conducted in these fungi suggest that the differences in mating specificity are determined by the architecture of the MAT1 locus. In self-fertile isolates that have not undergone unidirectional mating-type switching, the locus contains both MAT1-1 and MAT1-2 mating-type genes, typical of primary homothallism. In the self-sterile isolates produced after a switching event, the MAT1-2 genes are lacking from the locus, likely due to a recombination-mediated deletion of the MAT1-2 gene information. To determine whether these arrangements of the MAT1 locus support unidirectional mating-type switching in the Ceratocystidaceae, the largest known fungal assemblage capable of this reproduction strategy, a combination of genetic and genomic approaches were used. The MAT1 locus was annotated in representative species of Ceratocystis, Endoconidiophora, and Davidsoniella. In all cases, MAT1-2 genes interrupted the MAT1-1-1 gene in self-fertile isolates. The MAT1-2 genes were flanked by two copies of a direct repeat that accurately predicted the boundaries of the deletion event that would yield the MAT1 locus of self-sterile isolates. Although the relative position of the MAT1-2 gene region differed among species, it always disrupted the MAT1-1-1 gene and/or its expression in the self-fertile MAT1 locus. Following switching, this gene and/or its expression was restored in the self-sterile arrangement of the locus. This mirrors what has been reported in other species capable of unidirectional mating-type switching, providing the strongest support for a conserved MAT1 locus structure that is associated with this process. This study contributes to our understanding of the evolution of unidirectional mating-type switching.

A repertoire of candidate effector proteins of the fungus Ceratocystis cacaofunesta

The genus Ceratocystis includes many phytopathogenic fungi that affect different plant species. One of these is Ceratocystis cacaofunesta, which is pathogenic to the cocoa tree and causes Ceratocystis wilt, a lethal disease for the crop. However, little is known about how this pathogen interacts with its host. The knowledge and identification of possible genes encoding effector proteins are essential to understanding this pathosystem. The present work aimed to predict genes that code effector proteins of C. cacaofunesta from a comparative analysis of the genomes of five Ceratocystis species available in databases. We performed a new genome annotation through an in-silico analysis. We analyzed the secretome and effectorome of C. cacaofunesta using the characteristics of the peptides, such as the presence of signal peptide for secretion, absence of transmembrane domain, and richness of cysteine residues. We identified 160 candidate effector proteins in the C. cacaofunesta proteome that could be classified as cytoplasmic (102) or apoplastic (58). Of the total number of candidate effector proteins, 146 were expressed, presenting an average of 206.56 transcripts per million. Our database was created using a robust bioinformatics strategy, followed by manual curation, generating information on pathogenicity-related genes involved in plant interactions, including CAZymes, hydrolases, lyases, and oxidoreductases. Comparing proteins already characterized as effectors in Sordariomycetes species revealed five groups of protein sequences homologous to C. cacaofunesta. These data provide a valuable resource for studying the infection mechanisms of these pathogens in their hosts.

Whole genome sequencing and analysis of multiple isolates of Ceratocystis destructans, the causal agent of Ceratocystis canker of almond in California

Ceratocystis canker caused by Ceratocystis destructans is a severe disease of almond, reducing the longevity and productivity of infected trees. Once the disease has established in an individual tree, there is no cure, and management efforts are often limited to removing the infected area of cankers. In this study, we present the genome assemblies of five C. destructans isolates isolated from symptomatic almond trees. The genomes were assembled into a genome size of 27.2 ± 0.9 Mbp with an average of 6924 ± 135 protein-coding genes and an average GC content of 48.8 ± 0.02%. We concentrated our efforts on identifying putative virulence factors of canker pathogens. Analysis of the secreted carbohydrate-active enzymes showed that the genomes harbored 83.4 ± 1.8 secreted CAZymes. The secreted CAZymes covered all the known categories of CAZymes. AntiSMASH revealed that the genomes had at least 7 biosynthetic gene clusters, with one of the non-ribosomal peptide synthases encoding dimethylcoprogen, a conserved virulence determinant of plant pathogenic ascomycetes. From the predicted proteome, we also annotated cytochrome P450 monooxygenases, and transporters, these are well-established virulence determinants of canker pathogens. Moreover, we managed to identify 57.4 ± 2.1 putative effector proteins. Gene Ontology (GO) annotation was applied to compare gene content with two closely related species C. fimbriata, and C. albifundus. This study provides the first genome assemblies for C. destructans, expanding genomic resources for an important almond canker pathogen. The acquired knowledge provides a foundation for further advanced studies, such as molecular interactions with the host, which is critical for breeding for resistance.

Phospholipase C: Diverse functions in plant biotic stress resistance and fungal pathogenicity

Phospholipase C (PLC) generates various second messenger molecules and mediates phospholipid hydrolysis. In recent years, the important roles of plant and fungal PLC in disease resistance and pathogenicity, respectively, have been determined. However, the roles of PLC in plants and fungi are unintegrated and relevant literature is disorganized. This makes it difficult for researchers to implement PLC-based strategies to improve disease resistance in plants. In this comprehensive review, we summarize the structure, classification, and phylogeny of the PLCs involved in plant biotic stress resistance and fungal pathogenicity. PLCs can be divided into two groups, nonspecific PLC (NPC) and phosphatidylinositol-specific PLC (PI-PLC), which present marked differences in phylogenetic evolution. The products of PLC genes in fungi play significant roles in physiological activity and pathogenesis, whereas those encoded by plant PLC genes mediate the immune response to fungi. This review provides a perspective for the future control of plant fungal diseases.

Genomic and Pathogenicity Mechanisms of the Main Theobroma cacao L. Eukaryotic Pathogens: A Systematic Review

A set of diseases caused by fungi and oomycetes are responsible for large losses in annual world cocoa production. Managing the impact caused by these diseases is very complex because a common solution has yet to be found for different pathogens. In this context, the systematic knowledge of Theobroma cacao L. pathogens' molecular characteristics may help researchers understand the possibilities and limitations of cocoa disease management strategies. This work systematically organized and summarized the main findings of omics studies of T. cacao eukaryotic pathogens, focusing on the plant-pathogen interaction and production dynamics. Using the PRISMA protocol and a semiautomated process, we selected papers from the Scopus and Web of Science databases and collected data from the selected papers. From the initial 3169 studies, 149 were selected. The first author's affiliations were mostly from two countries, Brazil (55%) and the USA (22%). The most frequent genera were Moniliophthora (105 studies), Phytophthora (59 studies) and Ceratocystis (13 studies). The systematic review database includes papers reporting the whole-genome sequence from six cocoa pathogens and evidence of some necrosis-inducing-like proteins, which are common in T. cacao pathogen genomes. This review contributes to the knowledge about T. cacao diseases, providing an integrated discussion of T. cacao pathogens' molecular characteristics, common mechanisms of pathogenicity and how this knowledge is produced worldwide.

Uncovering a Complex Virome Associated with the Cacao Pathogens Ceratocystis cacaofunesta and Ceratocystis fimbriata

Theobroma cacao is one of the main crops of economic importance in the world as the source of raw material for producing chocolate and derivatives. The crop is the main source of income for thousands of small farmers, who produce more than 80% of the world's cocoa supply. However, the emergence, re-emergence and proliferation of pathogens, such as Ceratocystis spp., the causative agent of Ceratocystis wilt disease and canker disease, have been affecting the sustainability of many crops. Fungal control is laborious, often depending on fungicides that are expensive and/or toxic to humans, prompting researchers to look for new solutions to counteract the proliferation of these pathogens, including the use of biological agents such as mycoviruses. In this study, we investigated the diversity of microorganisms associated with the T. cacao pathogens Ceratocystis cacaofunesta and Ceratocystis fimbriata with a focus on the virome using RNA sequencing data available in public databases. We used a comprehensive bioinformatics pipeline containing several steps for viral sequence enrichment and took advantage of an integrated assembly step composed of different assemblers followed by sequence similarity searches using NCBI nonredundant databases. Our strategy was able to identify four putative C. cacaofunesta viruses (hypovirus, sclerotimonavirus, alphapartitivirus and narnavirus) and six C. fimbriata viruses (three alphaendornaviruses, one victorivirus and two mitoviruses). All the viral sequences identified showed similarity to viral genomes in public databases only at the amino acid level, likely representing new viral species. Of note, we present the first report of viruses associated with the cacao pathogens C. cacaofunesta and C. fimbriata and the second report of viral species infecting members of the Ceratocystidaceae family. Our findings highlight the need for further prospective studies to uncover the real diversity of fungus-infecting viruses that can contribute to the development of new management strategies.

Chromosomal polymorphism of the Ceratocystis fimbriata species complex in Brazil

Ceratocystis fimbriata is an important pathogen that causes wilt in several plant species. Despite the importance of this pathogen, knowledge about its karyotypic polymorphism and genomic architecture is limited. The main objective of this study was to investigate the karyotype of isolates of the C. fimbriata species complex from different host plants and geographical origins in Brazil. First, the identity of the isolates was confirmed conducting multilocus sequence analysis (MLSA) phylogeny using β-tubulin (TUBB), translation elongation factor 1α (TEF-1α) and mating-type (MAT1 and MAT2) gene sequences. To investigate the chromosomal polymorphism, two conditions of pulsed-field gel electrophoresis (PFGE) were used and the karyotypes of the isolates obtained. The retrotransposon-microsatellite amplified polymorphism (REMAP) molecular marker was utilized to assess the genetic variability among isolates. In the MLSA utilizing the concatenated gene sequences, Ceratocystis cacaofunesta and C. fimbriata formed separate clades, but considerable variation among C. fimbriata isolates was observed. Polymorphism in chromosome number and size was found, indicating the existence of genomic differences among isolates and occurrence of chromosomal rearrangements in the species complex. The number of chromosomes varied from seven to nine and the estimated minimum chromosome sizes were estimated to be between 2.7 to 6.0 Mbp. Small polymorphic chromosomes ranging from 1.2 to 1.8 Mbp were observed in all isolates, raising the hypothesis that they could be supernumerary chromosomes. REMAP analysis revealed a high genetic variability and that isolates from the same host tend to group together in a same cluster. Our results bring new insights into the chromosomal diversity and genome organization of the C. fimbriata complex.

Ceratocystis cacaofunesta differentially modulates the proteome in xylem-enriched tissue of cocoa genotypes with contrasting resistance to Ceratocystis wilt

Decreased accumulation of polyphenol oxidase, H₂O₂ accumulation, effective regulation of programmed cell death, and a protein predicted as allergenic can play key roles in cacao defense against Ceratocystis cacaofunesta. Ceratocystis wilt, caused by the fungus Ceratocystis cacaofunesta, has destroyed millions of Theobroma cacao trees in several countries of the Americas. Through proteomics, systems biology, and enzymatic analyses of infected stems, it was possible to infer mechanisms used by resistant (TSH1188) and susceptible (CCN51) cacao genotypes during infection. Protein extraction from xylem-enriched tissue of stems inoculated with the fungus and their controls 1 day after inoculation was carried out, followed by separation through two-dimensional gel electrophoresis and identification by mass spectrometry. Enzyme activity was determined at 1, 3, 7 and 15 days after inoculation. A total of 50 differentially accumulated distinct proteins were identified in the treatments of both genotypes and were classified into 10 different categories. An interaction network between homologous proteins from Arabidospsis thaliana was generated for each genotype, using the STRING database and Cytoscape software. Primary metabolism processes were apparently repressed in both genotypes. The resistance factors suggested for genotype TSH1188 were: H₂O₂ accumulation, effective regulation of programmed cell death, production of phytoalexins derived from tryptophan and furanocoumarins, and participation of a predicted allergenic protein with probable ribonuclease function inhibiting the germination and propagation of the fungus. In the susceptible genotype, it is possible that its recognition and signaling mechanism through proteins from the SEC14 family is easily overcome by the pathogen. Our results will help to better understand the interaction between cacao and one of its most aggressive pathogens, to create disease control strategies.

The Role of Fungi in the Cocoa Production Chain and the Challenge of Climate Change

Background: The role of fungi in cocoa crops is mainly associated with plant diseases and contamination of harvest with unwanted metabolites such as mycotoxins that can reach the final consumer. However, in recent years there has been interest in discovering other existing interactions in the environment that may be beneficial, such as antagonism, commensalism, and the production of specific enzymes, among others. Scope and approach: This review summarizes the different fungi species involved in cocoa production and the cocoa supply chain. In particular, it examines the presence of fungal species during cultivation, harvest, fermentation, drying, and storage, emphasizing the factors that possibly influence their prevalence in the different stages of production and the health risks associated with the production of mycotoxins in the light of recent literature. Key findings and conclusion: Fungi associated with the cocoa production chain have many different roles. They have evolved in a varied range of ecosystems in close association with plants and various habitats, affecting nearly all the cocoa chain steps. Reports of the isolation of 60 genera of fungi were found, of which only 19 were involved in several stages. Although endophytic fungi can help control some diseases caused by pathogenic fungi, climate change, with increased rain and temperatures, together with intensified exchanges, can favour most of these fungal infections, and the presence of highly aggressive new fungal genotypes increasing the concern of mycotoxin production. For this reason, mitigation strategies need to be determined to prevent the spread of disease-causing fungi and preserve beneficial ones.

Genome-Wide Identification and Expression Profile Analysis of the Phospholipase C Gene Family in Wheat (Triticum aestivum L.)

Phospholipid-hydrolyzing enzymes include members of the phospholipase C (PLC) family that play important roles in regulating plant growth and responding to stress. In the present study, a systematic in silico analysis of the wheat PLC gene family revealed a total of 26 wheat PLC genes (TaPLCs). Phylogenetic and sequence alignment analyses divided the wheat PLC genes into 2 subfamilies, TaPI-PLC (containing the typical X, Y, and C2 domains) and TaNPC (containing a phosphatase domain). TaPLC expression patterns differed among tissues, organs, and under abiotic stress conditions. The transcript levels of 8 TaPLC genes were validated through qPCR analyses. Most of the TaPLC genes were sensitive to salt stress and were up-regulated rapidly, and some were sensitive to low temperatures and drought. Overexpression of TaPI-PLC1-2B significantly improved resistance to salt and drought stress in Arabidopsis, and the primary root of P1-OE was significantly longer than that of the wild type under stress conditions. Our results not only provide comprehensive information for understanding the PLC gene family in wheat, but can also provide a solid foundation for functional characterization of the wheat PLC gene family.

Genome comparisons suggest an association between Ceratocystis host adaptations and effector clusters in unique transposable element families

Ceratocystis fimbriata is a host specific fungal pathogen of sweet potato (Ipomoea batatas). The closely related species, C. manginecans, is an important pathogen of trees (e.g. Acacia mangium and Mangifera indica) but has never been isolated from tuber crops. The genetic factors that determine the host range and host specificity of these species have not been determined. The aim of this study was to compare the genomes of C. fimbriata and C. manginecans in order to identify species-specific genetic differences that could be associated with host specificity. This included whole-genome alignments as well as comparisons of gene content and transposable elements (TEs). The genomes of the two species were found to be very similar, sharing similar catalogues of CAZymes, peptidases and lipases. However, the genomes of the two species also varied, harbouring species-specific genes (e.g. small secreted effectors, nutrient processing proteins and stress response proteins). A portion of the TEs identified (17%) had a unique distribution in each species. Transposable elements appeared to have played a prominent role in the divergence of the two species because they were strongly associated with chromosomal translocations and inversions as well as with unique genomic regions containing species-specific genes. Two large effector clusters, with unique TEs in each species, were identified. These effectors displayed non-synonymous mutations and deletions, conserved within a species, and could serve as mutational hot-spots for the development of host specificity in the two species.

Comparative genomic and transcriptomic analyses reveal different pathogenicity-related genes among three eucalyptus fungal pathogens

Ceratocystis fimbriata is an important plant pathogen known to cause Ceratocystis Wilt (CW), a prevalent fungal disease known to affect Eucalyptus spp. plantations in Brazil. To better understand the molecular mechanisms related to pathogenicity in eucalyptus, we generated a high-quality assembly and annotation of the Ce. fimbriata LPF1912 isolate (LPF1912) genome, as well as the first transcriptome of LPF1912 from 16 eucalyptus clones at three infection incubation periods (12, 18, and 24 h). The LPF1912 genome assembly contains 805 scaffolds, totaling 31.8 Mb, with 43% of the genome estimated to be coding sequence comprised of 7,390 protein-coding genes of which 626 (8.5%) were classified as secreted proteins, 120 ribosomal RNAs, and 532 transfer RNAs. Comparative genomic analysis among three eucalyptus fungal pathogens (Ce. fimbriata, Ce. eucalypticola, and Calonectria pseudoreteaudii), showed high similarity in the proteome (21.81%) and secretome (52.01%) of LPF1912 and Ce. eucalypticola. GO annotation of pathogenicity-related genes of LPF1912 and Ce. eucalypticola, revealed enrichment in cell wall degrading enzymes (CWDEs), and lipid/cutin metabolism for Ca. pseudoreteaudii. Additionally, a transcriptome analysis between resistant and susceptible eucalyptus clones to CW infection indicated that a majority (11) of LPF1912 differentially expressed genes had GO terms associated with enzymatic functions, such as the polygalacturonase gene family, confirming the crucial role of CWDEs for Ce. fimbriata pathogenicity. Finally, our genomic and transcriptomic analysis approach provides a better understanding of the mechanisms involved in Ce. fimbriata pathogenesis, as well as a framework for further studies.

IMA Genome-F 11: Draft genome sequences of Fusarium xylarioides, Teratosphaeria gauchensis and T. zuluensis and genome annotation for Ceratocystis fimbriata

Draft genomes of the fungal species Fusarium xylarioides, Teratosphaeria gauchensis and T. zuluensis are presented. In addition an annotation of the genome of Ceratocystis fimbriata is presented. Overall these genomes provide a valuable resource for understanding the molecular processes underlying pathogenicity and potential management strategies of these economically important fungi.

Ceratocystidaceae exhibit high levels of recombination at the mating-type (MAT) locus

Mating is central to many fungal life cycles and is controlled by genes at the mating-type (MAT) locus. These genes determine whether the fungus will be self-sterile (heterothallic) or self-fertile (homothallic). Species in the ascomycete family Ceratocystidaceae have different mating strategies, making them interesting to consider with regards to their MAT loci. The aim of this study was to compare the composition of the MAT locus flanking regions in 11 species of Ceratocystidaceae representing four genera. Genome assemblies for each species were examined to identify the MAT locus and determine the structure of the flanking regions. Large contigs containing the MAT locus were then functionally annotated and analysed for the presence of transposable elements. Genes typically flanking the MAT locus in sordariomycetes were found to be highly conserved in the Ceratocystidaceae. The different genera in the Ceratocystidaceae displayed little synteny outside of the immediate MAT locus flanking genes. Even though species ofCeratocystis did not show much synteny outside of the immediate MAT locus flanking genes, species of Huntiella and Endoconidiophora were comparatively syntenic. Due to the high number of transposable elements present in Ceratocystis MAT flanking regions, we hypothesise that Ceratocystis species may have undergone recombination in this region.

IMA Genome-F 9: Draft genome sequence of Annulohypoxylon stygium, Aspergillus mulundensis, Berkeleyomyces basicola (syn. Thielaviopsis basicola), Ceratocystis smalleyi, two Cercospora beticola strains, Coleophoma cylindrospora, Fusarium fracticaudum, Phialophora cf. hyalina, and Morchella septimelata

Draft genomes of the species Annulohypoxylon stygium, Aspergillus mulundensis, Berkeleyomyces basicola (syn. Thielaviopsis basicola), Ceratocystis smalleyi, two Cercospora beticola strains, Coleophoma cylindrospora, Fusarium fracticaudum, Phialophora cf. hyalina and Morchella septimelata are presented. Both mating types (MAT1-1 and MAT1-2) of Cercospora beticola are included. Two strains of Coleophoma cylindrospora that produce sulfated homotyrosine echinocandin variants, FR209602, FR220897 and FR220899 are presented. The sequencing of Aspergillus mulundensis, Coleophoma cylindrospora and Phialophora cf. hyalina has enabled mapping of the gene clusters encoding the chemical diversity from the echinocandin pathways, providing data that reveals the complexity of secondary metabolism in these different species. Overall these genomes provide a valuable resource for understanding the molecular processes underlying pathogenicity (in some cases), biology and toxin production of these economically important fungi.

Inheritance of phenotypic traits in the progeny of a Ceratocystis interspecific cross

Ceratocystis fimbriata is a fungal plant pathogen that causes black rot on Ipomoea batatas. Based on inoculation studies on numerous tree species, the pathogen is known to be host specific. The closely related species, Ceratocystis manginecans, causes severe wilt on a broad range of tree hosts, including Mangifera indica, Acacia mangium and other leguminous tree species. The genetic factors underlying the pathogenicity and host specificity of Ceratocystis species have rarely been investigated. In this study, an F₁ population of 70 recombinant progeny from a cross between C. fimbriata and C. manginecans was generated and the inheritance of various phenotypic traits was investigated. Results showed that colony colour, growth rate, asexual spore production and aggressiveness to I. batatas and A. mangium are all quantitative traits with high levels of heritability. However, conidia production and aggressiveness appeared to be regulated by a small number of genes. No correlation could be found between aggressiveness and other phenotypic traits, suggesting that these are inherited independently. This is the first study to consider genetic inheritance of pathogenicity and host specificity in Ceratocystis species and the results will contribute, in future, to the identification of quantitative trait loci and candidate genes associated with the traits investigated.