Rethinking the natural regeneration failure of pedunculate oak: The pathogen mildew hypothesis

Demeter, László; Molnár, Ábel; Öllerer, Kinga; Csóka, György; Kiš, Alen; Vadász, Csaba; Horváth, Ferenc; Molnár, Zsolt

doi:10.1016/j.biocon.2020.108928

Cited by 31 publications

(28 citation statements)

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“…Despite extensive research on their pathogenesis, epidemiology and control, these powdery mildew species remain amongst the economically most important plant pathogens in agriculture and horticulture worldwide due to the combined effect of costs of chemical crop protection measures and yield losses ( Calonnec et al, 2004 ; Fondevilla and Rubiales, 2012 ; Fuller et al, 2014 ; Dunn and Gaynor, 2020 ). Others are well-known tree pathogens ( Marçais and Desprez-Loustau, 2014 ; Demeter et al, 2021 ), and some have become model organisms in plant pathology research ( Gadoury et al, 2012 ; Bindschedler et al, 2016 ; Kuhn et al, 2016 ) or in the study of wild plant pathosystems ( Susi et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses

et al. 2022

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Powdery mildew fungi (Erysiphaceae), common obligate biotrophic pathogens of many plants, including important agricultural and horticultural crops, represent a monophyletic lineage within the Ascomycota. Within the Erysiphaceae, molecular phylogenetic relationships and DNA-based species and genera delimitations were up to now mostly based on nuclear ribosomal DNA (nrDNA) phylogenies. This is the first comprehensive genome-scale phylogenetic analysis of this group using 751 single-copy orthologous sequences extracted from 24 selected powdery mildew genomes and 14 additional genomes from Helotiales, the fungal order that includes the Erysiphaceae. Representative genomes of all powdery mildew species with publicly available whole-genome sequencing (WGS) data that were of sufficient quality were included in the analyses. The 24 powdery mildew genomes included in the analysis represented 17 species belonging to eight out of 19 genera recognized within the Erysiphaceae. The epiphytic genera, all but one represented by multiple genomes, belonged each to distinct, well-supported lineages. Three hemiendophytic genera, each represented by a single genome, together formed the hemiendophytic lineage. Out of the 14 other taxa from the Helotiales, Arachnopeziza araneosa, a saprobic species, was the only taxon that grouped together with the 24 genome-sequenced powdery mildew fungi in a monophyletic clade. The close phylogenetic relationship between the Erysiphaceae and Arachnopeziza was revealed earlier by a phylogenomic study of the Leotiomycetes. Further analyses of powdery mildew and Arachnopeziza genomes may discover signatures of the evolutionary processes that have led to obligate biotrophy from a saprobic way of life. A separate phylogeny was produced using the 18S, 5.8S, and 28S nrDNA sequences of the same set of powdery mildew specimens and compared to the genome-scale phylogeny. The nrDNA phylogeny was largely congruent to the phylogeny produced using 751 orthologs. This part of the study has revealed multiple contamination and other quality issues in some powdery mildew genomes. We recommend that the presence of 28S, internal transcribed spacer (ITS), and 18S nrDNA sequences in powdery mildew WGS datasets that are identical to those determined by Sanger sequencing should be used to assess the quality of assemblies, in addition to the commonly used Benchmarking Universal Single-Copy Orthologs (BUSCO) values.

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Section: Introductionmentioning

confidence: 99%

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses

et al. 2022

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“…This often leads to impeded natural regeneration [5,6]. Given the more prominent pressure of newly emerging invasive pathogens and pests, such as the oak lace bug (Corythuca arcuata (Say, 1832)), and spread of the already established ones ensuing from global trade and climate change, there is justified concern for the health status and regeneration of natural Q. robur forest stands both in the present and future [7,8].…”

Section: Introductionmentioning

confidence: 99%

Impact of Thermotherapy and Short-Term Storage on Quercus robur L. Acorn Mycobiota and Germination

Orlović

Drvodelić

Vukelić

et al. 2021

Forests

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When natural regeneration of Quercus robur stands is hampered by an insufficient acorn yield, human assisted sowing of acorns collected in non-affected stands and stored for some period of time is performed. To inhibit the development of fungi and acorn deterioration during storage, thermotherapy is usually applied by submerging acorns for 2.5 h in water heated to 41 °C. This research aimed to test the effect of four thermotherapy treatments of different durations and/or applied temperatures as well as short-term storage at −1 °C or 3 °C on acorn internal mycobiota and germination. Fungal presence in cotyledons was analyzed in 450 acorns by isolation of mycelia on artificial media, followed by a DNA-based identification. Germination of 2000 acorns was monitored in an open field trial. Thermotherapy significantly decreased fungal diversity, while storage at 3 °C increased the isolation frequency of several fungi, mainly Penicillium spp. The most frequently isolated fungi did not show a negative impact on acorn germination after short-term storage. The study confirmed the efficiency of thermotherapy in the eradication of a part of acorn internal mycobiota, but also its effect on the proliferation of fast-colonizing fungi during storage. However, the latter showed to be more stimulated by storage conditions, specifically by storage at 3 °C.

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“…Nursery production of oak seedlings can substantially contribute to the preservation of forest sustainability by ensuring sufficient amounts of high-quality seedlings with expected good field performance for the rapid and efficient assistance of hindered natural regeneration of oak forests in the cases of disturbances, which are occurring more frequently in recent decades [3,5,7,11]. Although morphological characteristics, especially the height and diameter, are easy to measure and quite reliable as indicators of the seedling quality and its chances for the successful survival and growth in the field [42], there are not many studies on the association of the acorn thermotherapy treatment with the morphology of related oak seedlings.…”

Section: Discussionmentioning

confidence: 99%

“…Its wood is utilized for the production of high-quality and construction timber and its forests harbor a variety of different animal, plant and fungal species, greatly contributing to the overall biodiversity [1,2]. However, these ecosystems and the benefits they provide are at risk of degradation, as the synergistic activity of various biotic and abiotic factors has led to their increased decline and impeded natural regeneration during the last decades [3][4][5][6]. One potential means of preservation of oak forest continuity in cases of hindered natural regeneration is to assist natural processes by sowing acorns collected in other areas or by planting oak seedlings produced in nurseries [7].…”

Section: Introductionmentioning

confidence: 99%

Effect of Acorn Thermotherapy and Short-Term Storage on Morphological Characteristics of Related Quercus Robur L. Seedlings

et al. 2022

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To preserve the sustainability of Quercus robur forests, which is at risk due to the disturbed natural regeneration, human assisted sowing of acorns or planting of oak seedlings is often performed. However, the success of these methods depends greatly on the use of high-quality sowing and planting material. Thermotherapy is thus often employed to decrease the acorn mycobiota and maintain their quality during the storage. The aim of this study was to test the impact of acorn thermotherapy, followed by a short-term storage at −1 °C or 3 °C, on the quality of related oak seedlings, which was assessed based on the easily observable morphological characteristics. Height, root collar diameter and seedling form were measured or noted for the 1284 and 1190 seedlings at the age of four months and three years, respectively. It was found that acorn thermotherapy affirmatively affected seedling height, especially at the early growth stage. Positive impact on other seedling attributes could not be decisively confirmed because of the lack of the continuity of the effect (not visible in both younger and older seedlings) and the prevailing impact of other factors. Different acorn thermotherapy conditions (temperature and duration) and short-term storage temperatures appeared to be associated only with the occurrence of stem forking at the earlier stage of seedling growth.

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Rethinking the natural regeneration failure of pedunculate oak: The pathogen mildew hypothesis

Cited by 31 publications

References 53 publications

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses

Beyond Nuclear Ribosomal DNA Sequences: Evolution, Taxonomy, and Closest Known Saprobic Relatives of Powdery Mildew Fungi (Erysiphaceae) Inferred From Their First Comprehensive Genome-Scale Phylogenetic Analyses

Impact of Thermotherapy and Short-Term Storage on Quercus robur L. Acorn Mycobiota and Germination

Effect of Acorn Thermotherapy and Short-Term Storage on Morphological Characteristics of Related Quercus Robur L. Seedlings

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