Paratracheal abscess by plant fungus Chondrostereum purpureum- first case report of human infection

Chondrostereum purpureum, is a plant fungus causing silver leaf disease of plants, particularly of the rose family. Here we report a case of paratracheal abscess caused by C. purpureum. This is a first of its kind of a case wherein this plant fungus caused disease in a human. Conventional techniques (microscopy and culture) failed to identify the fungus. Only by sequencing, the identity of this unusual pathogen could be revealed. This case highlights the potential of environmental plant fungi to cause disease in humans and stresses the importance of molecular techniques to identify the causative fungal species.

Comparative Efficacy of Chondrosterum purpureum and Chemical Herbicides for Control of Resprouts in Tanoak and Bay Laurel

The invasive Oomycete pathogen Phytophthora ramorum has killed millions of susceptible oak and tanoak trees in California and southern Oregon forests and is responsible for losses in revenue to the nursery industry through mitigation activities. In addition, infestation of forests in the United Kingdom by this organism has resulted in the destruction of many hectares of larch plantations. Resprouting stumps can be a reservoir for the inoculum of P. ramorum persisting on a site. In areas where the application of herbicides is not permitted, a biocontrol treatment would be an indispensable alternative. Treatment of stumps with the sap-rotting fungus Chondrostereum purpureum (Pers.) Pouzar has been shown to be an effective tool for the suppression of resprouting on several species, most notably red alder. In this project, the ability of C. purpureum to suppress resprouting was evaluated on stumps of two host species, tanoak (Notholithocarpus densiflorus) and California bay laurel (Umbellularia californica). Laboratory testing of three California isolates of C. purpureum indicated that the fungus can colonize bay laurel stems. Field trials were established near Brookings, Oregon, on tanoak and on bay laurel near Soquel, California. Early results of field testing showed that C. purpureum was able to colonize the stumps of tanoak following treatment and was found to occur naturally on tanoak logs and stumps. Formulations of C. purpureum appear to have some effect on reducing sprout survival in tanoak, but the most effective and rapid treatment for this host is the hack and squirt method of applying the herbicide imazapyr. Sprayed herbicide prevents sprouting on bay laurel, and there was evidence that resprouting was inhibited on stumps treated with C. purpureum. Over time, applications of C. purpureum may be a more permanent solution as the stumps begin to decay.

Covalent Immobilization of Chondrostereum purpureum Endopolygalacturonase on Ferromagnetic Nanoparticles: Catalytic Properties and Biotechnological Application

Pectinases are widely used in a variety of industrial processes. However, their application is limited by low catalytic processivity, reduced stability, high cost, and poor re-use compatibility. These drawbacks may be overcome by enzyme immobilization with ferromagnetic nanoparticles, which are easily recovered by a magnetic field. In this work, an endopolygalacturonase from Chondrostereum purpureum (EndoPG_Cp) expressed in Pichia pastoris was immobilized on glutaraldehyde-activated chitosan ferromagnetic nanoparticles (EndoPG_Cp-MNP) and used to supplement a commercial enzyme cocktail. No significant differences in biochemical and kinetic properties were observed between EndoPG_Cp-MNP and EndoPG_Cp, although the EndoPG_Cp-MNP showed slightly increased thermostability. Cocktail supplementation with EndoPG_Cp-MNP increased reducing sugar release from orange wastes by 1.8-fold and showed a synergistic effect as compared to the free enzyme. Furthermore, EndoPG_Cp-MNP retained 65% of the initial activity after 7 cycles of re-use. These properties suggest that EndoPG_Cp-MNP may find applications in the processing of pectin-rich agroindustrial residues.

Endophytic Microorganisms Associated with Reversion of Silverleaf Disease Symptoms in Apple

Silverleaf is caused by the fungus Chondrostereum purpureum, which produces wood necrosis and foliar silvering in woody plants. Field observations and studies in apple have shown the reversion of foliar symptoms. Because plants were clones and received identical agronomical management, it was hypothesized that reversion is driven by endophytic microbiota. Thus, the objectives of this study were to compare healthy, diseased, and reverted plants with respect to their physiology, endophytic microbial communities, antagonistic ability of their endophytes against C. purpureum, and defense genes expression. Water potential, stomatal conductance, chlorophyll content, and fluorescence were measured. Endophytic bacterial and fungal DNA were analyzed by denaturing gradient gel electrophoresis, and community richness and similarity were calculated. Wood cores were collected and bacterial and fungal endophytes were isolated and confronted with C. purpureum-virulent strains in dual-culture assays. Defense genes expression was measured by quantitative PCR. Results indicated that there were no differences in physiological parameters between healthy and reverted plants, except for fluorescence, and both type of plants differed from diseased ones. Bacterial and fungal community richness was similar in healthy and reverted plants and higher than in diseased ones. Endophytes from reverted and healthy plants showed high antagonism to C. purpureum. Furthermore, nonexpressor of pathogenesis-related gene 1 expression was upregulated in reverted plants, whereas phenylalanine ammonia lyase and polygalacturonase-inhibiting protein genes showed higher values in diseased plants. Overall, physiological, molecular, and microbial characteristics were similar between healthy and reverted plants, and both differed from diseased ones. Therefore, reversion of symptoms is associated with changes in the endophytic microbiota, which seems to be a promising source of biological control agents against C. purpureum.

A PCR-Based Method for the Rapid Detection of Chondrostereum purpureum in Apple

Silverleaf caused by the basidiomycete Chondrostereum purpureum affects numerous woody species, including fruit tree crops like apple, resulting in wood necrosis and foliar silvering. There are no curative alternatives for this disease, and its management is by prevention methods. Therefore, the aim of this study was to develop a rapid diagnostic tool for the detection and identification of C. purpureum directly from woody tissues to help distinguish the pathogen from other basidiomycetes that are commonly found on apple. The silverleaf pathogen was isolated from different hosts and locations, and Koch's postulates were performed by inoculating the isolates on apple cuttings and measuring internal necrosis. A previously described APN 1 pair of primers specificity was also tested against 25 C. purpureum isolates in this study, using other wood rotting species as negative controls. Seven virulent isolates were inoculated on apple cuttings, and DNA was extracted from the cuttings' sawdust and amplified using APN 1, after 22 days of incubation. To prove the efficiency of the method in the field, DNA from healthy nursery plants inoculated with two virulent isolates, and naturally infected plants showing different levels of foliar symptoms, were tested. Presence of the fungus was verified by reisolation on APDA in all assays. Koch's postulates indicated that all C. purpureum isolates were pathogenic, showing different virulence levels, and APN 1 primers were able to discriminate them from other basidiomycetes. The method was also able to detect C. purpureum from artificially inoculated plants as well as naturally infected ones, demonstrating that the protocol may become a rapid minimally destructive diagnostic tool to detect the pathogen without the need to isolate it from tissues, and thus taking measures to prevent its dissemination.