Weather Variables Associated with Spore Dispersal of Lecanosticta acicola Causing Pine Needle Blight in Northern Spain

In the last decade, the impact of needle blight fungal pathogens on the health status of forests in northern Spain has marked a turning point in forest production systems based on Pinus radiata species. Dothistroma needle blight caused by Dothistroma septosporum and D. pini, and brown spot needle blight caused by Lecanosticta acicola, coexist in these ecosystems. There is a clear dominance of L. acicola with respect to the other two pathogens and evidence of sexual reproduction in the area. Understanding L. acicola spore dispersal dynamics within climatic determinants is necessary to establish more efficient management strategies to increase the sustainability of forest ecosystems. In this study, spore counts of 15 spore traps placed in Pinus ecosystems were recorded in 2019 and spore abundance dependency on weather data was analysed using generalised additive models. During the collection period, the model that best fit the number of trapped spores included the daily maximum temperature and daily cumulative precipitation, which was associated to higher spore counts. The presence of conidia was detected from January and maximum peaks of spore dispersal were generally observed from September to November.

Blowin’ in the Wind: Wind Dispersal Ability of Phytopathogenic Fusarium in a Wind Tunnel Experiment

Dispersal processes play an essential role in cereal diseases caused by phytopathogenic Fusarium. However, most empirical studies of Fusarium spore dispersal have focused on vertical transport by rain splash, while wind dispersal has been mostly neglected. Our objective was to determine the ability of Fusarium conidiospores to disperse via wind under controlled conditions in a wind tunnel study. Ten Fusarium species with diverse spore varieties were studied by placing them in the wind stream at wind velocities of 5 and 8 m s−1 and collecting them after 6 m and a period of 1 h using a newly developed air sampling box. Although spore concentrations were high in the releasing Petri Dishes, the tested isolates were recaptured in only 18 of 78 runs. F. equiseti and F. cerealis were the most frequently recovered species. Changing abiotic conditions, wind speed, and spore shapes had no significant effect on Fusarium spore recapture rates. Another experiment showed that conidiospores were rarely released from the grown mycelium. Therefore, the importance of wind alone as a dispersal medium for Fusarium conidiospores may have been overestimated so far. Further studies should investigate the importance of carrier media or mobile linkers combined with the wind dispersal of spores.

Diversity, Dispersal and Mode of Reproduction of Amanita exitialis in Southern China

Amanita exitialis is a poisonous mushroom and has caused many deaths in southern China. In this study, we collected 118 fruiting bodies of A. exitialis from seven different sites in Guangdong Province in southern China and investigated their genetic relationships using 14 polymorphic molecular markers. These 14 markers grouped the 118 fruiting bodies into 20 multilocus genotypes. Among these 20 genotypes, eight were each found only once while the remaining 12 were each represented by two to 54 fruiting bodies. Interestingly, among the 12 shared genotypes, four were shared between/among local populations that were separated by as far as over 80 km, a result consistent with secondary homothallic reproduction and long-distance spore dispersal. Despite the observed gene flow, significant genetic differentiations were found among the local populations, primarily due to the over-representation of certain genotypes within individual local populations. STRUCTURE analyses revealed that the 118 fruiting bodies belonged to three genetic clusters, consistent with divergence within this species in this geographic region. Interestingly, we found an excess of heterozygous individuals at both the local and the total sample level, suggesting potential inbreeding depression and heterozygous advantage in these populations of A. exitialis. We discuss the implications of our results for understanding the life cycle, dispersal, and evolution of this poisonous mushroom.

Monitoring spore dispersal and early infections of Diplocarpon coronariae causing apple blotch using selected spore traps and a new qPCR method

Apple blotch (AB) is a major disease of apples in Asia and recently also emerging in Europe and the USA. It is caused by the fungus Diplocarpon coronariae (Dc) (formerly: Marssonina coronaria; teleomorph: Diplocarpon mali) and leads to severe defoliation of apple trees in late summer and thus to reduced yield and fruit quality. To develop effective crop protection strategies, a sound knowledge of the pathogen's biology is crucial. However, especially data on the early phase of disease development is scarce, and no data on spore dispersal for Europe is available. In this study, we assessed different spore traps for their capacity to capture Dc spores, and we developed a highly sensitive TaqMan qPCR method to quantify Dc conidia in spore trap samples. With these tools, we monitored the temporal and spatial spore dispersal and disease progress in spring and early summer in an extensively managed apple orchard in Switzerland in 2019 and 2020. Our results show that Dc overwinters in leaf litter and that spore dispersal and primary infections occur already in late April and beginning of May. We provide the first results on early-season spore dispersal of Dc, which, combined with the observed disease progress, helps to understand the disease dynamics and improve disease forecast models. Using the new qPCR method, we finally detected Dc in buds, on bark and on fruit mummies, suggesting that these apple organs may serve as additional overwintering habitats for the fungus.

Zombie ant graveyard dynamics in Gunung Mulu National Park

Ophiocordyceps is a genus of pathogenic fungi, which predominantly parasitise insects. This study investigates the spatial dynamics of zombie ant graveyards, and explores the optimal height for Ophiocordyceps unilateralis spore dispersal in a Bornean rainforest. While there is considerable research derived from alternative tropical regions, there is limited documentation of Ophiocordyceps fungi in Borneo. This paper aims to build on the current body of knowledge, focusing on the spatial dynamics of zombie ant graveyards, and in particular the height at which infected ants are found. In the present study, an area of Gunung Mulu National Park was searched for O. unilateralis-infected ants. Once an infected ant was located, the surrounding area was methodically searched to allow for the height and location of all surrounding ants to be recorded. Infected ants were found at variable heights between the four sites (means of 28.9–57.6 cm) above the expected height laid out in similar studies (approximately 25 cm). It is suggested that these heights may correspond to locations at which temperature and humidity are optimal for spore dispersal and fungal growth and that these heights differ depending on unique features of the environment.

Dynamics of Diaporthe ampelina conidia released from grape canes that overwintered in the vineyard

Phomopsis cane and leaf spot (PCLS) is an important disease of grapevines, which is mainly caused by Diaporthe ampelina. Dispersal dynamics of D. ampelina spores were investigated in two vineyards, one in North Italy and one in Montenegro, by using spore samplers that collected alpha and beta conidia from rain water running off from PCLS-affected canes. The canes were collected from each vineyard, deployed and overwintered in the corresponding vineyards. In each of three years (2016, 2017, and 2018), conidial dispersal was investigated during one (Montenegro) or two (Italy) growing seasons following the deployment of the PCLS-affected canes. In the first growing season following cane deployment in both vineyards, alpha conidia were mostly found in runoff water after grapevine bud break, especially in April and May, and beta conidia were regularly found in numbers comparable to alpha conidia, most frequently from June to September. In Italy, high numbers of alpha and beta conidia were also collected during the second growing season following cane deployment. The dispersal dynamics of alpha conidia over time were described by a Gompertz equation using hydrothermal time (i.e., the accumulated effect of temperature on the maturation rate of pycnidia on days in which the number of hours of wetness was ≥ 6 or 9 h), with R2 and concordance correlation coefficient >0.9. Rain (≥ 0.2 mm) was a good predictor of conidial dispersal, with an overall accuracy of 0.97. These results increase our understanding of D. ampelina spore dispersal and should be integrated into warning systems for PCLS management.

Palaeomycology: A modern mycological view of fungal palynomorphs

Fungal spores are increasingly used as reliable proxies in paleoenvironmental reconstructions; however, little attention is paid to the ecological tolerances of the fungi themselves and the signal the fungi provide. This chapter provides a much-needed background in fungal biology and ecology of monophyletic Dikarya (Ascomycota and Basidiomycota), as well as taphonomic considerations which could be included in any use as palaeoecological indicators. It is intended to help those who are interested in using fungal spores as palaeoecological indicators to make more informed interpretations. A recapitulation of spore dispersal strategies and distances is presented for a better understanding of the transport mechanisms of fungal spores. Likewise, pigmentation is discussed, as it results in significant taphonomic bias in fossil fungal assemblages and, as some dark-colored pigmentation is authigenic while some develops during taphonomy. A key element of this chapter is discussion of the environmental role of fungi, including modern versus palaeo-approaches to fungal ecology, fungal assemblages, and diversity patterns as diagnostic tools to infer paleoenvironments.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5342039

Developmental innovations promote species diversification in mushroom-forming fungi

Fungi evolved complex fruiting body (‘mushroom’) morphologies as adaptations to efficient spore dispersal in terrestrial habitats. Mushroom-forming fungi (Agaricomycetes) display a graded series of developmental innovations related to fruiting body morphology, however, how these evolved is largely unknown, leaving the functional biology and evolutionary principles of complex multicellularity in the third largest multicellular kingdom poorly known. Here, we show that developmental innovations of mushroom-forming fungi that enclose the spore-producing surface (hymenophore) in a protected environment display significant asymmetry in their evolution and are associated with increased diversification rates. ‘Enclosed’ development and related tissues (partial and universal veils) evolved convergently and became a widespread developmental type in clades in which it emerged. This probably mirrors increased fitness for protected fruiting body initials in terrestrial habitats, by better coping with environmental factors such as desiccation or predators, among others. We observed similar patterns in the evolution of complex hymenophore architectures, such as gills, pores or teeth, which optimize biomass-to-propagule number ratios and were found to spur diversification in mushrooms. Taken together, our results highlight new morphological traits associated with the adaptive radiation of mushroom-forming fungi and present formal phylogenetic testing of hypotheses on the reproductive ecology of a poorly known but hyperdiverse clade.