Studies on Rhizina undulata

Disaster Plant Pathology: Smart Solutions for Threats to Global Plant Health from Natural and Human-Driven Disasters

Disaster plant pathology addresses how natural and human-driven disasters impact plant diseases and the requirements for smart management solutions. Local to global drivers of plant disease change in response to disasters, often creating environments more conducive to plant disease. Most disasters have indirect effects on plant health through factors such as disrupted supply chains and damaged infrastructure. There is also the potential for direct effects from disasters, such as pathogen or vector dispersal due to floods, hurricanes, and human migration driven by war. Pulse stressors such as hurricanes and war require rapid responses, whereas press stressors such as climate change leave more time for management adaptation but may ultimately cause broader challenges. Smart solutions for the effects of disasters can be deployed through digital agriculture and decision support systems supporting disaster preparedness and optimized humanitarian aid across scales. Here, we use the disaster plant pathology framework to synthesize the effects of disasters in plant pathology and outline solutions to maintain food security and plant health in catastrophic scenarios. We recommend actions for improving food security before and following disasters, including (i) strengthening regional and global cooperation, (ii) capacity building for rapid implementation of new technologies, (iii) effective clean seed systems that can act quickly to replace seed lost in disasters, (iv) resilient biosecurity infrastructure and risk assessment ready for rapid implementation, and (v) decision support systems that can adapt rapidly to unexpected scenarios. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

In Vitro Observations of the Interactions between Pholiota carbonaria and Polytrichum commune and Its Potential Environmental Relevance

Wildfires play a critical role in maintaining biodiversity and shaping ecosystem structure in fire-prone regions, and successional patterns involving numerous plant and fungal species in post-fire events have been elucidated. Evidence is growing to support the idea that some post-fire fungi can form endophytic/endolichenic relationships with plants and lichens. However, no direct observations of fire-associated fungal-moss interactions have been visualized to date. Therefore, physical interactions between a post-fire fungus, Pholiota carbonaria, and a moss, Polytrichum commune, were visually examined under laboratory conditions. Fungal appressoria were visualized on germinating spores and living protonemata within two weeks of inoculation in most growth chambers. Appressoria were pigmented, reddish gold to braun, and with a penetration peg. Pigmented, reddish gold to braun fungal hyphae were associated with living tissue, and numerous mature rhizoids contained fungal hyphae at six months. Inter-rhizoidal hyphae were pigmented and reddish gold to braun, but no structures were visualized on mature gametophyte leaf or stem tissues. Based on our visual evidence and previous work, we provide additional support for P. carbonaria having multiple strategies in how it obtains nutrients from the environment, and provide the first visual documentation of these structures in vitro.

Pyrophilous fungi detected after wildfires in the Great Smoky Mountains National Park expand known species ranges and biodiversity estimates

Following a late fall wildfire in 2016 in the Great Smoky Mountains National Park, pyrophilous fungi in burn zones were documented over a 2-y period with respect to burn severity and phenology. Nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) barcodes were obtained to confirm morphological evaluations. Forty-one taxa of Ascomycota and Basidiomycota were identified from burn sites and categorized as fruiting only in response to fire or fruiting enhanced by fire. Twenty-two species of Pezizales (Ascomycota) were among the earliest to form ascomata in severe burn zones, only one of which had previously been documented in the Great Smoky Mountains National Park. Nineteen species of Basidiomycota, primarily Agaricales, were also documented. Among these, only five species (Coprinellus angulatus, Gymnopilus decipiens, Lyophyllum anthracophilum, Pholiota carbonicola, and Psathyrella pennata) were considered to be obligate pyrophilous taxa, but fruiting of two additional taxa (Hygrocybe conica and Mycena galericulata) was clearly enhanced by fire. Laccaria trichodermophora was an early colonizer of severe burn sites and persisted through the winter of 2017 and into spring and summer of 2018, often appearing in close association with Pinus pungens seedlings. Fruiting of pyrophilous fungi peaked 4-6 mo post fire then diminished, but some continued to fruit up to 2.5 y after the fire. In all, a total of 27 previously unrecorded taxa were added to the All Taxa Biodiversity Inventory (ATBI) database (~0.9%). Most pyrophilous fungi identified in this study are either cosmopolitan or have a Northern Hemisphere distribution, but cryptic endemic lineages were detected in Anthracobia and Sphaerosporella. One new combination, Hygrocybe spadicea var. spadicea f. odora, is proposed.

Genetic differentiation in Eurasian populations of the postfire ascomycete Daldinia loculata

The genetic population structure of the postfire ascomycete Daldinia loculata was studied to test for differentiation on a continental scale. Ninety-six samples of spore families, each comprising mycelia from six to 10 spores originating from single perithecia, were sampled from one Russian and six Fennoscandian forest sites. Allelic distribution was assayed for six nuclear gene loci by restriction enzyme analyses of polymerase chain reaction (PCR)-amplified gene fragments. In addition, the full sequence of the gene fragment was analysed for a subset of haploid single-ascospore isolates in a multiallelic approach. A third data set was generated by using arbitrary-primed PCR with the core sequence of the phage M13 as primer. Although there was a reduction in heterozygosity in the total population from what would have been expected at random mating, the levels of genetic differentiation among the Eurasian subpopulations of D. loculata were low. All subpopulations were found to be in Hardy-Weinberg equilibrium and gametic equilibrium was observed between all investigated nuclear gene loci. The results obtained by the different markers were consistent; we confirmed low levels of genetic differentiation among the Eurasian subpopulations of D. loculata. The differentiation did not increase with distance; the Russian subpopulation, sampled more than 7000 km from the Fennoscandian subpopulations, was only moderately differentiated from the others (FST = 0.00-0.14). In contrast, one of the Swedish populations was the most highly differentiated from the others, with FST and GST values of 0.10-0.16. The results suggest that D. loculata consists of a long-lived background Eurasian population of latent mycelia in nonburned forests, established by sexual ascospores dispersed from scattered burned forest sites. Local differentiation is probably due to founder effects of populations in areas with low fire frequency. A tentative life cycle of D. loculata is presented.

Effects of microwave treatment of soil on growth of birch (Betula pendula) seedlings and infection of them by ectomycorrhizal fungi

Seedlings of birch (Betula pendula Roth.) were grown for 12 weeks in small volumes of field soils heated in a microwave (MW) oven for different times and then either supplemented or not with inocula of ectomycorrhizal fungi and, in one case, with fresh agricultural soil. Growth of roots and shoots was assessed, and the incidence of different mycorrhizal types, distinguished by colour and morphology, was recorded. Bacterial and fungal populations were determined by dilution plating after MW treatment of soils. In four soils, shoot and root growth were markedly enhanced by MW treatments that raised the soil temperature to 60°C or more, irrespective of the exposure times (20-50 s) needed for this. Shoot dry weights were increased 1·9- to 2·9-fold by MW treatment of two soils from young (11-16 years) birch stands, compared with 8·0- and 11·4-fold for two soils from old birchwoods. But MW treatment of a colliery spoil reduced shoot growth 5-fold. The growth responses were not related to the size of seedlings in untreated soils. The responses coincided with substantial reductions in the total populations of bacteria and fungi. Hebeloma subsaponaceum Karsten developed similar numbers of mycorrhizas from mycelial inoculum added to untreated and MW treated soil. But Lactarius pubescent (Fr. ex Krombh.) Fr. developed significantly more mycorrhizas from inoculum added to MW-treated soil than to untreated soil. This difference between the fungi accords with their classification as, respectively, early stage and late stage in reported mycorrhizal successions on birch. Some mycorrhizal types developed on seedlings from resident inoculum in soil. Their incidence was reduced by different amounts following MW treatment, suggesting differences in heat-tolerance of their propagules. Hebeloma sacchariolens Quel., which forms sclerotium-like bodies and which probably developed from resident inoculum, was unaffected by MW treatment of soil. Some mycorrhizal fungi, notably Thelephora terrestris (Ehrh.) Fr., developed in place of others in soils treated for long times (80-180 s), and they probably developed from airborne spores.