Genetic variation in the genus Leptographium with special reference to Leptographium wageneri

The objectives of this research were to determine genetic variation in Leptographium and how it corresponds to the taxonomy of the genus. The similarity of 88 strains of 27 species of Leptographium was studied using enzyme electrophoresis. UGPMA cluster analysis of similarity matrices (Nei genetic identity, I) generated from data of 267 electrophoretic forms (electromorphs) of 15 enzymes showed a close correspondence between morphology and electrophoretic similarity. Strains of a species clustered at I $\geq$ 0.60, but in two cases, taxa clustered at I $\u3e$ 0.60, suggesting conspecificity. Additional isozyme studies were made of 76 isolates of Leptographium wageneri representing three host-specialized varieties. Of 21 enzymes tested, 10 were polymorphic, having from two to six electromorphs. Only 14 combinations (electrophoretic types) of the 29 electromorphs were found; each electrophoretic type was restricted to a single variety. Within each variety, one electrophoretic type was abundant and broadly distributed; additional types were geographically isolated or restricted. Ordination of Nei genetic distance (D) among strains revealed three discrete clusters that corresponded to the three varieties. Nei gene diversity (H) in each variety was low (0.017 to 0.040), but differentiation between varieties was high; the Nei coefficient of gene differentiation (G\sb{\rm st}) for the species was 0.860. Vegetative compatibility was tested among the same L. wageneri isolates by pairing auxotrophic, nitrate non-utilizing mutants on nitrate media. The development of dense hyphal growth in the zone of confrontation between complementing phenotypes indicated compatibility. Heterokaryons were recovered from hyphal tips and conidiophores of complementing pairings. Only fourteen groups of vegetatively compatible isolates (VC groups) were detected. Each contained isolates that were of similar electrophoretic types, and most had unique geographic ranges. No intervarietal complementation occurred. The indications of low genetic diversity in Leptographium wageneri (i.e., few electrophoretic types and VC groups), the unique geographic distributions of the electrophoretic and compatibility phenotypes, and the correlation between electrophoretic type and VC group may be due to a lack of recombination, to strong clonal selection and to founder effects

Recovery Plan for Scots Pine Blister Rust Caused by Cronartium pini

Peer reviewedPostprin

Pest categorisation of Cronartium spp. (non-EU)

Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Cronartium spp. (non-EU), a well-defined and distinguishable group of fungal pathogens of the family Cronartiaceae. There are at least 40 species described within the Cronartium genus, of which two are considered native to the EU (C. gentianeum and C. pini) and one has been introduced in the 19th century (C. ribicola) and is now widespread in the EU – these three species are thus not part of this pest categorisation. In addition, the non-EU C. harknessii, C. kurilense and C. sahoanum were already dealt with in a previous pest categorisation. All the non-EU Cronartium species are not known to be present in the EU and are regulated in Council Directive 2000/29/EC (Annex IAI) as harmful organisms whose introduction into the EU is banned. Cronartium spp. are biotrophic obligate plant pathogens. Many of the North American Cronartium species alternate between the aecial host Pinus spp. and telial hosts of various dicotyledonous plants. C. conigenum, C. orientale, C. quercuum and C. strobilinum have different Quercus spp. as their telial hosts. C. orientale and C. quercuum also infect Castanea spp. and Castanopsis spp. The pathogens could enter the EU via host plants for planting and cut flowers and branches. Non-EU Cronartium spp. could establish in the EU, as climatic conditions are favourable to many of them and Pinus and Quercus spp. are common. The pathogens would be able to spread following establishment by movement of host plants, as well as natural spread. Should non-EU Cronartium spp. be introduced in the EU, impacts can be expected on pine, oak and chestnut woodlands, plantations, ornamental trees and nurseries. The Cronartium species present in North America cause important tree diseases. Symptoms on Pinus spp. differ between Cronartium spp., but include galls, cankers, dieback of branches and stems, deformity, tree and cone death. The main knowledge gap concerns the limited available information on (sub)tropical Cronartium spp. The criteria assessed by the Panel for consideration of Cronartium spp. (non-EU) as potential quarantine pests are met, while, for regulated non-quarantine pests, the criterion on the pest presence in the EU is not met

A review of wheat diseases – a field perspective

Wheat is one of the primary staple foods throughout the planet. Significant yield gains in wheat production over the past 40 years have resulted in a steady balance of supply versus demand. However, predicted global population growth rates and dietary changes mean that substantial yield gains over the next several decades will be needed to meet this escalating demand. A key component to meeting this challenge is better management of fungal incited diseases, which can be responsible for 15%–20% yield losses per annum. Prominent diseases of wheat that currently contribute to these losses include the rusts, blotches and head blight/scab. Other recently emerged or relatively unnoticed diseases, such as wheat blast and spot blotch, respectively, also threaten grain production. This review seeks to provide an overview of the impact, distribution and management strategies of these diseases. In addition, the biology of the pathogens and the molecular basis of their interaction with wheat are discussed

Resolution of a neurotrophic keratopathy associated hypopyon with cenegermin

Purpose: We present a novel case of a neurotrophic keratopathy associated inflammatory hypopyon that resolved after initiation of therapy with cenegermin (Oxervate; Dompe, Milan, Italy), a recombinant human nerve growth factor (rhNGF). This finding illustrates the potential of cenegermin in advanced inflammatory neurotrophic disease. Observations: A 60-year-old female with a history of herpes zoster keratitis was evaluated in our clinic for stage 2 neurotrophic keratopathy. One month later, she presented emergently with a large epithelial defect, infiltrate, and hypopyon. Three separate sets of corneal cultures returned negative. She was treated with oral antivirals and aggressive topical antibiotics with no clinical improvement. Given the presumed diagnosis of stage 3 neurotrophic keratopathy with a sterile hypopyon, she was started on cenegermin 6 times daily for 8 weeks in the absence of a corticosteroid. By 2 weeks after starting cenegermin, the epithelial defect, infiltrate, and hypopyon sizes had improved. Within 4 weeks of starting cenegermin, the hypopyon had clinically resolved. The patient was subsequently started on topical corticosteroid drops for the last 4 weeks of cenegermin therapy. Examination at the conclusion of 8 weeks of cenegermin treatment revealed a closed epithelium and minimal scar. Best-corrected visual acuity with contact lens overrefraction was 20/70. Over the course of 7 months of continued follow-up, the cornea remained epithelialized without recurrent corneal infiltration or hypopyon. Conclusions and importance: While cenegermin has been previously shown to be an effective treatment for neurotrophic keratopathy associated epithelial defects, resolution of a neurotrophic keratopathy associated inflammatory hypopyon with cenegermin is novel