Chrysoporthe Cubensis Research Articles

Increased enzymatic hydrolysis of sugarcane bagasse from enzyme recycling.

BackgroundDevelopment of efficient methods for production of renewable fuels from lignocellulosic biomass is necessary to maximize yields and reduce operating costs. One of the main challenges to industrial application of the lignocellulosic conversion process is the high costs of cellulolytic enzymes. Recycling of enzymes may present a potential solution to alleviate this problem. In the present study enzymes associated with the insoluble fraction were recycled after enzymatic hydrolysis of pretreated sugarcane bagasse, utilizing different processing conditions, enzyme loadings, and solid loadings.ResultsIt was found that the enzyme blend from Chrysoporthe cubensis and Penicillium pinophilum was efficient for enzymatic hydrolysis and that a significant portion of enzyme activity could be recovered upon recycling of the insoluble fraction. Enzyme productivity values (g glucose/mg enzyme protein) over all recycle periods were 2.4 and 3.7 for application of 15 and 30 FPU/g of glucan, representing an increase in excess of ten times that obtained in a batch process with the same enzyme blend and an even greater increase compared to commercial cellulase enzymes.ConclusionsContrary to what may be expected, increasing lignin concentrations throughout the recycle period did not negatively influence hydrolysis efficiency, but conversion efficiencies continuously improved. Recycling of the entire insoluble solids fraction was sufficient for recycling of adhered enzymes together with biomass, indicative of an effective method to increase enzyme productivity.

Production and application of an enzyme blend from Chrysoporthe cubensis and Penicillium pinophilum with potential for hydrolysis of sugarcane bagasse

Blending of the enzyme extracts produced by different fungi can result in favorable synergetic enhancement of the enzyme blend with regards to the main cellulase activities, as well as the inclusion of accessory enzymes that may not be as abundant in enzyme extracts produced by predominantly cellulase producing fungi. The Chrysoporthe cubensis:Penicillium pinophilum 50:50 (v/v) blend produced herein presented good synergy, especially for FPase and endoglucanase activities which were 76% and 48% greater than theoretical, respectively. This enzyme blend was applied to sugarcane bagasse previously submitted to a simple alkali pretreatment. Glucan hydrolysis efficiency reached an excess of 60% and xylan conversion exceeded 90%. Increasing the hydrolysis temperature from 45 to 50°C also resulted in a 16-20% increase in conversion of both glucan and xylan fractions. The blended enzyme extract obtained therefore showed great potential for application in the lignocellulose hydrolysis process.

Chrysoporthe cubensis: A new source of cellulases and hemicellulases to application in biomass saccharification processes

The plant pathogenic fungus Chrysoporthe cubensis was cultivated under solid state employing different substrates and the highest endoglucanase (33.84Ug−1), FPase (2.52Ug−1), β-glucosidase (21.55Ug−1) and xylanase (362.38Ug−1) activities were obtained using wheat bran as carbon source. Cellulases and xylanase produced by C. cubensis showed maximal hydrolysis rate at pH 4.0 and in a temperature range of 50–60°C. All enzymatic activities were highly stable at 40 and 50°C through 48h of pre-incubation. Saccharification of alkaline pretreated sugarcane bagasse by crude enzyme extract from C. cubensis resulted in release of 320.8mg/g and 288.7mg/g of glucose and xylose, respectively. On another hand, a similar assay employing commercial cellulase preparation resulted in release of 250.6mg/g and 62.1mg/g of glucose and xylose, respectively. Cellulolytic extract from C. cubensis showed a great potential to be used in biomass saccharification processes.

Host switching between native and non‐native trees in a population of the canker pathogen Chrysoporthe cubensis from Colombia

The purpose of this study was to test the hypothesis that Chrysoporthe cubensis on native trees in South America could be the source of the pathogen that causes severe stem cankers and often mortality in commercially propagated Eucalyptus trees. This was done by investigating populations originating from two adjacent Eucalyptus (Myrtaceae) plantations in Colombia, and wild Miconia rubiginosa trees (Melastomataceae) growing alongside these stands. Polymorphic microsatellite markers were used to quantify allele sizes in 20 and 39 isolates from the two Eucalyptus stands and 32 isolates from adjacent M. rubiginosa trees. Gene and genotypic diversities were calculated from these data, and population differentiation and assignment tests were performed to ascertain whether the populations were genetically different. Results showed that there were no differences between any of the populations using these techniques, and that they can be treated as a single population. Therefore, the results support the hypothesis that host switching has occurred in C. cubensis in Colombia.

Hybrids and mini-cutting: a powerful combination that has revolutionized the Eucalyptusclonal forestry

Background Eucalypt canker disease (Chrysoporthe cubensis) was the main driver of the concept of eucalypt clonal forestry in Brazil. Initially clonal forestry was based on outstanding spontaneous hybrids resistant to canker disease. Since the recognition that cloning superior inter-specific hybrids could be an important general strategy, several crosses were made for many different purposes, especially pulp & paper, charcoal and more recently veneer and solid wood. This strategy has been responsible for a significant advance in the forest productivity of Eucalyptus. The underlying foundation for this strategy has been the exploitation of heterosis observed in most inter-specific crosses. Due to its importance, hybridization and cloning currently constitute a key component of almost all forest-based industrial plantations in Brazil. Significant progress has taken place in the last few years with the different techniques used to carry out controlled crosses and cloning.

Multigene phylogenetic and population differentiation data confirm the existence of a cryptic species within Chrysoporthe cubensis

Chrysoporthe cubensis is one of the most important pathogens of Eucalyptus. Based on phylogenetic evidence and geographic origin, isolates of this fungus are known to reside in distinct ‘South America’ and ‘Southeast Asia’ clades. In this study, reproductive isolation amongst these isolates of C. cubensis was tested using gene flow statistics for 12 polymorphic loci, and to support these data, phylogenetic affiliations based on gene trees and a multigene phylogeny were used. Gene flow statistics between populations, and relative to the closely related Chrysoporthe austroafricana, were low and not significantly different ( P < 0.05). Additionally, phylogenetic analyses of DNA sequence data for four gene regions convincingly distinguished the two subclades of C. cubensis. Isolates in the Southeast Asian subclade are described in the new species, Chrysoporthe deuterocubensis. Chrysoporthe cubensis and C. deuterocubensis represent closely related fungi that are thought to be native to South America and Southeast Asia, respectively. A technique is presented that allows for rapid differentiation between these species and that will aid in quarantine procedures to limit their spread to new environments.

Identification and Pathogenicity of Chrysoporthe cubensis on Eucalyptus and Syzygium spp. in South China.

The genus Chrysoporthe includes important pathogens of plantation-grown Eucalyptus spp. and has been reported from several tree genera in the order Myrtales in tropical and subtropical areas of the world. During disease surveys in South China, fruiting structures typical of Chrysoporthe spp. were observed on cankers on Eucalyptus spp. and Syzygium cumini trees. The aim of this study was to confirm the identity of the Chrysoporthe cubensis infecting the Eucalyptus spp. and S. cumini and to test the pathogenicity of the fungus. Following glasshouse trials to select virulent isolates, field inoculations were undertaken to screen different commercial Eucalyptus genotypes for their susceptibility to the fungus. Isolates were characterized based on their morphology and DNA sequence data for the β-tubulin and internal transcribed spacer regions of the ribosomal DNA. Results showed that the putative pathogen represented the Asian form of C. cubensis, which occurred on numerous different Eucalyptus spp. and hybrid clones as well as S. cumini. Field inoculations showed that all six of the Eucalyptus genotypes tested are susceptible to infection by C. cubensis. Significant differences were observed between them, providing prospects to select disease-tolerant planting stock in the future.

First report of Chrysoporthe cubensis from Eucalyptus in Ghana

During disease surveys of Eucalyptus grandis, E. camaldulensis and E. dagambae in the Ashanti, Central and Eastern Provinces of Ghana in February 2007 stem cankers on mature E. dagambae, resembling that caused by species of Chrysoporthe, were observed in a single compartment near Kumasi. Infection was visible only as stem cankers, characterized by cracked bark, mostly at the bases of trees, bearing long necked fungal fruiting bodies, visible with the naked eye or a hand lens. Some cankers girdled the entire tree. Orange spore masses were transferred aseptically from the tips of the fruiting bodies to malt extract agar in Petri dishes. Fungal isolates were identified using DNA sequence data of the rDNA (ITS, 5·8S) (GenBank Accession No. GQ292541) and beta tubulin gene regions (GU014577). Isolates from Ghana represent C. cubensis, grouping with isolates in the South American clade and similar to isolates from the Republic of Congo and Cameroon (Roux et al., 2003; Gryzenhout et al., 2004). This is in contrast to C. cubensis isolates from East Africa which group in the Asian clade (Nakabonge et al., 2006). Sixteen isolates of C. cubensis, obtained from 16 separate trees, were assessed for their phenotypic diversity. This was done by vegetative compatibility grouping (VCG) of single hyphal tip isolates on oatmeal agar. All isolates, except one, resided in a single VCG type, supporting suggestions that C. cubensis in West Africa has been introduced (Wingfield, 2003). Two isolates of C. cubensis from Ghana were inoculated into the stems of ten trees each of a 1-year-old E. grandis clone in the greenhouse. After 6 weeks lesions had formed in the bark and cambium, stretching into the xylem of inoculated trees. Chrysoporthe cubensis was successfully re-isolated. No lesions were formed in the control inoculations. This is the first report of C. cubensis from Ghana and attacking E. dagambae, expanding the host and geographic range of this possibly introduced pathogen (Nakabonge et al., 2006) in Africa. The National Research Foundation of South Africa (NRF) funded the research.

Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis.

Chrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis.

TheEucalyptuscanker pathogenChrysoporthe cubensisdiscovered in eastern Australia

Chrysoporthe cubensis is an important pathogen of commercially planted Eucalyptus species (Myrtaceae) in tropical and subtropical parts of the world where these trees are planted as non-natives. Although the majority of Eucalyptus spp. are native to Australia, Chr. cubensis is not common there and has been reported only once from naturally growing Eucalyptus marginata in Western Australia. Chr. cubensis is able to infect hosts in the Myrtaceae and Melastomataceae other than Eucalyptus, but has not been found on hosts other than Eucalyptus in Australia. Recently, fruiting structures resembling those of Chr. cubensis were discovered on Tibouchina heteromalla, planted as a non-native in the Botanical Gardens in Cairns, northern Queensland. These fruiting structures and resulting isolates were characterised as Chr. cubensis in this study. Pathogenicity studies found that Corymbia spp., including commercially important spotted gum, are susceptible along with E. pilularis and E. dunnii. The discovery of Chr. cubensis on a non-native plant in the northern part of Australia is important as it might imply that the pathogen has been introduced into the country and pose a significant threat to native Eucalyptus forests. Alternatively, this fungus might occur naturally in the area on hosts other than Tibouchina, possibly Eucalyptus or related species, and that Australia forms part of its native range.

First record of natural infection of Marlierea edulis by the eucalyptus canker fungus Chrysoporthe cubensis

Eucalyptus is the most important plant genus for forest plantations worldwide, including Brazil where approximately 3 million ha are cultivated. Chrysoporthe cubensis (formerly known as Cryphonectria cubensis) is the aetiological agent of eucalyptus canker, one of the most serious diseases of eucalypt. Although in the past this fungus was only known to attack eucalyptus and cloves, it is now known to attack other hosts in the Myrtaceae and Melastomataceae families (Wingfield, 2003; Seixas et al., 2004; Rodas et al., 2005). A host-range study involving wound inoculations with an isolate from eucalyptus indicated a potentially wide host range for this fungus, particularly within the order Myrtales (Seixas et al., 2004). Among the species found susceptible in this test was Marlierea edulis, popularly known in Brazil as ‘cambucá’. This is a large, native tree of the Brazilian tropical rainforest and a minor fruit tree occasionally grown as a curiosity in orchards. Recently, M. edulis was found in the field (Saquarema, State of Rio de Janeiro, Brazil) showing typical canker symptoms: necrotic wounds with cracking and flaking of the bark that led to branch death. Diseased tissue showed abundant, black, spine-like perithecial ostioles. The fungus had the typical morphology of C. cubensis: ascomata perithecial, subglobose 205–445 × 220–440 µm, ostioles rostrate 300–750 × 65–125 µm; asci unitunicate, clavate 15–28 × 3–5 µm; ascospores ellipsoid, 5–7 × 1–3 µm, one-septate and hyaline. A sample was deposited in the local herbarium (VIC 27828). Wound inoculations of an isolate obtained from this host using the bark-replacement method (Ferreira, 1989) on adult, healthy specimens of both M. edulis and Corymbia citriodora (=Eucalyptus citriodora) resulted in typical canker symptoms and abundant formation of sporulating C. cubensis perithecia after 3 weeks. This is the first record of natural infection by this fungus on M. edulis, and the third native host for this fungus to be found in the field in Brazil. This finding confirms the susceptibility under natural conditions of plants included in the host-range study performed by Seixas et al. (2004). The demonstration of pathogenicity of an isolate obtained from M. edulis to eucalyptus represents additional evidence for the hypothesis that native plants serve as reservoirs for eucalyptus canker outbreaks in Brazil.

Novel hosts of the Eucalyptus canker pathogen Chrysoporthe cubensis and a new Chrysoporthe species from Colombia

The pathogen Chrysoporthe cubensis (formerly Cryphonectria cubensis) is best known for the important canker disease that it causes on Eucalyptus species. This fungus is also a pathogen of Syzygium aromaticum (clove), which is native to Indonesia, and like Eucalyptus, is a member of Myrtaceae. Furthermore, C. cubensis has been found on Miconia spp. native to South America and residing in Melastomataceae. Recent surveys have yielded C. cubensis isolates from new hosts, characterized in this study based on DNA sequences for the ITS and β-tubulin gene regions. These hosts include native Clidemia sericea and Rhynchanthera mexicana ( Melastomataceae) in Mexico, and non-native Lagerstroemia indica (Pride of India, Lythraceae) in Cuba. Isolates from these hosts and areas group in the sub-clade of C. cubensis accommodating the South American collections of the fungus. This sub-clade also includes isolates recently collected from Eucalyptus in Cuba, which are used to epitypify C. cubensis. New host records from Southeast Asia include exotic Tibouchina urvilleana from Singapore and Thailand and native Melastoma malabathricum ( Melastomataceae) in Sumatra, Indonesia. Consistent with their areas of occurrence isolates from the latter collections group in the Asian sub-clade of C. cubensis. DNA sequence comparisons of isolates from Tibouchina lepidota in Colombia revealed that they represent a new sub-clade within the greater Chrysoporthe clade. Isolates in this clade are described as Chrysoporthe inopina sp. nov., based on distinctive morphological differences.

Distribution of Chrysoporthe Canker Pathogens on Eucalyptus and Syzygium spp. in Eastern and Southern Africa

Chrysoporthe cubensis and C. austroafricana, collectively known as Cryphonectria cubensis in the past, are important canker pathogens of Eucalyptus spp. worldwide. Previous studies have suggested that Chrysoporthe austroafricana occurs only in South Africa, whereas C. cubensis occurs in Australia, Cameroon, Tanzania, Democratic Republic of Congo, Republic of Congo, Southeast Asia, and South, Central, and North America. In South Africa, C. austroafricana is a pathogen on nonnative Eucalyptus (Myrtaceae) and Tibouchina (Melastomataceae) spp., both residing in the order Myrtales. Recently, the fungus also has been found on native Syzygium cordatum trees in the country, leading to the hypothesis that it is native to Africa. In contrast, C. cubensis is thought to have been introduced into Africa and is known only on non-native Eucalyptus spp. and S. aromaticum (clove) in four countries. The aim of this study was to consider the distribution of Chrysoporthe spp. on non-native Eucalyptus spp. as well as on native Myrtales in southern and eastern Africa. Isolates were collected from as many trees as possible and characterized based on their morphology and DNA sequence data for two gene regions. Results show, for the first time, that C. cubensis occurs in Kenya, Malawi, and Mozambique on nonnative Eucalyptus spp. C. austroafricana was found for the first time in Mozambique, Malawi, and Zambia on non-native Eucalyptus spp. and native S. cordatum. The known distribution range of C. austroafricana within South Africa also was extended during these surveys.

Aurapex penicillata gen. sp. nov. from native Miconia theaezans and Tibouchina spp. in Colombia

Conidiomata of a fungus resembling Chrysoporthe cubensis, a serious canker pathogen of Eucalyptus spp. (Myrtaceae, Myrtales) in tropical and subtropical parts of the world, was found on Eucalyptus grandis in Colombia. Fruiting structures of the fungus could be distinguished from those of C. cubensis by their distinctly orange conidiomatal necks. This fungus also was found on several plant species native to Colombia including Tibouchina urvilleana, T. lepidota and Miconia theaezans (Melastomataceae, Myrtales). Morphological comparisons, as well as those based on sequences of the ITS1/ITS2 region of the ribosomal DNA repeat and the β-tubulin gene, were used to characterize this fungus. Its pathogenicity was assessed on various plants from which it has been collected, either in field or greenhouse trials. Phylogenetic analyses showed that isolates reside in a clade distinct from the four clades accommodating Chrysoporthe, Cryphonectria, Endothia and Rostraureum. Members of this clade are distinguished by the presence of orange conidiomatal necks with black bases and a unique internal stromatal structure. No teleomorph has been found for this fungus, for which we have provided the name Aurapex penicillata gen. sp. nov. A. penicillata produced only small lesions after inoculation on young T. urvilleana, M. theaezans and E. grandis trees and appears not to be a serious pathogen.

Aurapex penicillata gen. sp. nov. from native Miconia theaezans and Tibouchina spp. in Colombia

Conidiomata of a fungus resembling Chrysoporthe cubensis, a serious canker pathogen of Eucalyptus spp. (Myrtaceae, Myrtales) in tropical and subtropical parts of the world, was found on Eucalyptus grandis in Colombia. Fruiting structures of the fungus could be distinguished from those of C. cubensis by their distinctly orange conidiomatal necks. This fungus also was found on several plant species native to Colombia including Tibouchina urvilleana, T. lepidota and Miconia theaezans (Melastomataceae, Myrtales). Morphological comparisons, as well as those based on sequences of the ITS1/ITS2 region of the ribosomal DNA repeat and the beta-tubulin gene, were used to characterize this fungus. Its pathogenicity was assessed on various plants from which it has been collected, either in field or greenhouse trials. Phylogenetic analyses showed that isolates reside in a clade distinct from the four clades accommodating Chrysoporthe, Cryphonectria, Endothia and Rostraureum. Members of this clade are distinguished by the presence of orange conidiomatal necks with black bases and a unique internal stromatal structure. No teleomorph has been found for this fungus, for which we have provided the name Aurapex penicillata gen. sp. nov. A. penicillata produced only small lesions after inoculation on young T. urvilleana, M. theaezans and E. grandis trees and appears not to be a serious pathogen.

Discovery of the Eucalyptus canker pathogen Chrysoporthe cubensis on native Miconia (Melastomataceae) in Colombia

Chrysoporthe cubensis is one of the most serious canker pathogens on commercially grown Eucalyptus species in the tropics and subtropics. During recent surveys for native hosts of C. cubensis in Colombia, fungi with fruiting structures similar to those of C. cubensis were found on native Miconia theaezans and Miconia rubiginosa, both members of the Melastomataceae. These fungi were identified based on morphology and DNA sequences of the ITS1/ITS2 region of the rDNA operon and the β‐tubulin genes. The majority of isolates from M. theaezans and M. rubiginosa grouped together with South American C. cubensis isolates from Eucalyptus species and Syzygium aromaticum (clove). However, some of the isolates from M. theaezans grouped with isolates of Chrysoporthella hodgesiana, another anamorph species linked to Chrysoporthe, from Tibouchina spp. in Colombia. Pathogenicity of these fungi was assessed on various Melastomataceae. Miconia rubiginosa was more susceptible to infection by C. cubensis than two Eucalyptus clones. Isolates of C. cubensis and Chrysop. hodgesiana were mildly pathogenic on the various hosts included in the pathogenicity trials, and most pathogenic on Tibouchina urvilleana and Tibouchina lepidota.