Search Results (6)

The deployment of Eucalyptus pellita trees that are resistant to Ceratocystis manginecans is essential for the commercial plantations and therefore the sustainability of forest industries in Southeast Asia that utilize this resource. Current screening procedures are time-consuming and expensive but could be expedited with the aid of marker-assisted selection and breeding. The identification of genotypes with resistance to the disease may be facilitated if microsatellite markers developed in other Eucalyptus species are transferable and can be linked to quantitative trait loci (QTL) for disease resistance. This possibility was tested in 111 full-sib progenies and their parents by genotyping with 49 microsatellite markers developed in other Eucalyptus species. Disease development was assessed after stem inoculation with C. manginecans isolate Am60C. The disease index (DI) varied from 0 to 20% of stem length. There was a continuous distribution of resistant and susceptible seedlings with 60% in the resistant category. Of the 30 acceptable markers, 17 (56%) defined two linkage groups (LG). In each LG, one QTL with a significant logarithm of odds (LODs > 13) was identified. The transferability of microsatellite markers developed in other Eucalyptus species facilitated the rapid identification of LGs and QTLs in E. pellita. To further refine the linkage map, the testing of more microsatellite markers and a larger population of progenies are required. Full article

Hybridization is recognized as a notable driver of evolution and adaptation, which closely related species may exploit in the form of incomplete reproductive barriers. Three closely related species of Ceratocystis (i.e., C. fimbriata, C. manginecans and C. eucalypticola) have previously been shown to hybridize. In such studies, naturally occurring self-sterile strains were mated with an unusual laboratory-generated sterile isolate type, which could have impacted conclusions regarding the prevalence of hybridization and inheritance of mitochondria. In the current study, we investigated whether interspecific crosses between fertile isolates of these three species are possible and, if so, how mitochondria are inherited by the progeny. For this purpose, a PCR-RFLP method and a mitochondrial DNA-specific PCR technique were custom-made. These were applied in a novel approach of typing complete ascospore drops collected from the fruiting bodies in each cross to distinguish between self-fertilizations and potential hybridization. These markers showed hybridization between C. fimbriata and C. eucalypticola and between C. fimbriata and C. manginecans, while no hybridization was detected in the crosses involving C. manginecans and C. eucalypticola. In both sets of hybrid progeny, we detected biparental inheritance of mitochondria. This study was the first to successfully produce hybrids from a cross involving self-fertile isolates of Ceratocystis and also provided the first direct evidence of biparental mitochondrial inheritance in the Ceratocystidaceae. This work lays the foundation for further research focused on investigating the role of hybridization in the speciation of Ceratocystis species and if mitochondrial conflict could have influenced the process. Full article

The planted forest area in Vietnam increased from 3.0 to 4.4 million hectares in the period 2010–2020, but the loss of productivity from pests and diseases continues to be a problem. During this period, frequent and systematic plantation forest health surveys were conducted on 12 native and 4 exotic genera of trees as well as bamboo across eight forest geographic regions of Vietnam. Damage caused by insects and pathogens was quantified in the field and laboratory in Hanoi. The threats of greatest concern were from folivores (Antheraea frithi, Arthroschista hilaralis, Atteva fabriciella, Hieroglyphus tonkinensis, Lycaria westermanni,Krananda semihyalina, and Moduza procris), wood borers (Batocera lineolata, Euwallacea fornicatus, Tapinolachnus lacordairei, Xyleborus perforans, and Xystrocera festiva), sap-sucking insects (Aulacaspis tubercularis and Helopeltis theivora) and pathogens (Ceratocystis manginecans, Fusarium solani, and Phytophthora acaciivora). The number of new and emerging pests and pathogens increased over time from 2 in 2011 to 17 in 2020, as the damage became more widespread. To manage these pests and diseases, it is necessary to further invest in the selection and breeding of resistant genotypes, improve nursery hygiene and silvicultural operations, and adopt integrated pest management schemes. Consideration should be given to developing forest health monitoring protocols for forest reserves and other special-purpose forests. Full article

Species in the Ceratocystis manginecans complex are important fungal pathogens of plantation trees globally. The most important hosts include species of Eucalyptus, Acacia, Mangifera, and Punica. Despite their relevance and widespread occurrence, little is known regarding their population genetics and how this might relate to their host associations or geographic regions in which they occur. A global collection of 491 isolates representing the C. manginecans complex, from four different plant hosts and nine countries, were genotyped using microsatellite markers. Population genetic analyses using numerous tools were conducted to interrogate how their genetic diversity and structure might be affected by host or areas of occurrence. Results of genetic diversity studies showed that when grouping isolates into populations based on their host associations, the population on Eucalyptus was most diverse, and it also has a broad global distribution. When considering countries of origin as a basis for defining populations, the gene and genotypic diversity were highest in populations from China, Indonesia, and Brazil. In contrast, populations from Oman and Pakistan collected from Mangifera had the lowest genetic diversity and were clonal. Molecular variance, population differentiation, and network and structure analyses showed that the genetic structure of isolates in the C. manginecans complex is influenced by both host association as well as geographical isolation. Furthermore, the results reflected the movement of genotypes between plant hosts and geographic regions that have implications regarding the broad global distribution of this pathogen. Full article

Terpenes represent the biggest group of natural compounds on earth. This large class of organic hydrocarbons is distributed among all cellular organisms, including fungi. The different classes of terpenes produced by fungi are mono, sesqui, di- and triterpenes, although triterpene ergosterol is the main sterol identified in cell membranes of these organisms. The availability of genomic data from members in the Ceratocystidaceae enabled the detection and characterization of the genes encoding the enzymes in the mevalonate and ergosterol biosynthetic pathways. Using a bioinformatics approach, fungal orthologs of sterol biosynthesis genes in nine different species of the Ceratocystidaceae were identified. Ergosterol and some of the intermediates in the pathway were also detected in seven species (Ceratocystis manginecans, C. adiposa, Huntiella moniliformis, Thielaviopsis punctulata, Bretziella fagacearum, Endoconidiophora polonica and Davidsoniella virescens), using gas chromatography-mass spectrometry analysis. The average ergosterol content differed among different genera of Ceratocystidaceae. We also identified all possible terpene related genes and possible biosynthetic clusters in the genomes used in this study. We found a highly conserved terpene biosynthesis gene cluster containing some genes encoding ergosterol biosynthesis enzymes in the analysed genomes. An additional possible terpene gene cluster was also identified in all of the Ceratocystidaceae. We also evaluated the sensitivity of the Ceratocystidaceae to a triazole fungicide that inhibits ergosterol synthesis. The results showed that different members of this family behave differently when exposed to different concentrations of triazole tebuconazole. Full article

In 2018, the area of plantation forests in Indonesia reached 8,668,670 ha. Pests and diseases have been considered as critical factors in sustainable production of plantation forests in the humid tropic areas. With the introduction of new plant species such as fast-growing plants of acacias and eucalypts, new pests and diseases have become emerging threats. Several pathogenic fungi and bacteria have been recorded in plantation forests in Indonesia since their early establishment. The fungal species associated with the most common diseases include Ceratocystis manginecans (Ceratocystis wilt and dieback), Ganoderma philippii (red root rot), Phellinus noxius (brown root rot and heart rot), and Fusarium spp. (Fusarium wilt), whereas the major bacterial pathogens are Ralstonia spp. (bacterial wilt) and Xanthomonas spp. (leaf streak). As one key component of integrated pest management, biocontrol measure plays significant roles in managing major diseases of tropical plantation forests in Indonesia. A number of forestry companies have put development of biocontrol agents as one of their priority research programs. For this scenario, antagonists have been collected and isolated from different ecosystems. This paper reviews development of biocontrol agents to manage major diseases of tropical plantation forests in Indonesia. Full article