scholarly journals Cold Acclimation in Brachypodium Is Accompanied by Changes in Above-Ground Bacterial and Fungal Communities

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2824
Author(s):  
Collin L. Juurakko ◽  
George C. diCenzo ◽  
Virginia K. Walker
Keyword(s):  
Cold Acclimation ◽  
Pseudomonas Syringae ◽  
Ribosomal Rna ◽  
Brachypodium Distachyon ◽  
Amplicon Sequencing ◽  
Fungal Communities ◽  
Internal Transcribed Spacer Region ◽  
Beneficial Bacterium ◽  
Freeze Stress ◽  
Growing Conditions

Shifts in microbiota undoubtedly support host plants faced with abiotic stress, including low temperatures. Cold-resistant perennials prepare for freeze stress during a period of cold acclimation that can be mimicked by transfer from growing conditions to a reduced photoperiod and a temperature of 4 °C for 2–6 days. After cold acclimation, the model cereal, Brachypodium distachyon, was characterized using metagenomics supplemented with amplicon sequencing (16S ribosomal RNA gene fragments and an internal transcribed spacer region). The bacterial and fungal rhizosphere remained largely unchanged from that of non-acclimated plants. However, leaf samples representing bacterial and fungal communities of the endo- and phyllospheres significantly changed. For example, a plant-beneficial bacterium, Streptomyces sp. M2, increased more than 200-fold in relative abundance in cold-acclimated leaves, and this increase correlated with a striking decrease in the abundance of Pseudomonas syringae (from 8% to zero). This change is of consequence to the host, since P. syringae is a ubiquitous ice-nucleating phytopathogen responsible for devastating frost events in crops. We posit that a responsive above-ground bacterial and fungal community interacts with Brachypodium’s low temperature and anti-pathogen signalling networks to help ensure survival in subsequent freeze events, underscoring the importance of inter-kingdom partnerships in the response to cold stress.

scholarly journals Fungal Diversity in the Phyllosphere of Pinus heldreichii H. Christ—An Endemic and High-Altitude Pine of the Mediterranean Region

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 172 ◽  
Author(s):  
Jelena Lazarević ◽  
Audrius Menkis
Keyword(s):  
High Altitude ◽  
Bark Beetles ◽  
Fungal Pathogens ◽  
High Throughput Sequencing ◽  
Fungal Communities ◽  
High Quality ◽  
The Balkans ◽  
Fungal Community Structure ◽  
Growing Conditions ◽  
Coniferous Tree Species

Pinus heldreichii is a high-altitude coniferous tree species naturaly occurring in small and disjuncted populations in the Balkans and southern Italy. The aim of this study was to assess diversity and composition of fungal communities in living needles of P. heldreichii specifically focusing on fungal pathogens. Sampling was carried out at six different sites in Montenegro, where 2-4 year-old living needles of P. heldreichii were collected. Following DNA isolation, it was amplified using ITS2 rDNA as a marker and subjected to high-throughput sequencing. Sequencing resulted in 31,831 high quality reads, which after assembly were found to represent 375 fungal taxa. The detected fungi were 295 (78.7%) Ascomycota, 79 (21.0%) Basidiomycota and 1 (0.2%) Mortierellomycotina. The most common fungi were Lophodermium pinastri (12.5% of all high-quality sequences), L. conigenum (10.9%), Sydowia polyspora (8.8%), Cyclaneusma niveum (5.5%), Unidentified sp. 2814_1 (5.4%) and Phaeosphaeria punctiformis (4.4%). The community composition varied among different sites, but in this respect two sites at higher altitudes (harsh growing conditions) were separated from three sites at lower altitudes (milder growing conditions), suggesting that environmental conditions were among major determinants of fungal communities associated with needles of P. heldreichii. Trees on one study site were attacked by bark beetles, leading to discolouration and frequent dieback of needles, thereby strongly affecting the fungal community structure. Among all functional groups of fungi, pathogens appeared to be an important component of fungal communities in the phyllosphere of P. heldreichii, especially in those trees under strong abiotic and biotic stress.

scholarly journals Development of Resistance to Hymexazol Among Pythium Species in Cucumber Greenhouses in Oman

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 202-208 ◽  
Author(s):  
Zainab M. Al-Balushi ◽  
Hesham Agrama ◽  
Issa H. Al-Mahmooli ◽  
Sajeewa S. N. Maharachchikumbura ◽  
Abdullah M. Al-Sadi
Keyword(s):  
Ribosomal Rna ◽  
Management Strategies ◽  
Soil Samples ◽  
Integrated Disease Management ◽  
Pythium Species ◽  
Internal Transcribed Spacer Region ◽  
Development Of Resistance ◽  
The Common ◽  
Cucumber Roots ◽  
Further Development

A study was conducted to characterize the common Pythium spp. in greenhouses in Oman and their level of resistance to hymexazol, a widely used fungicide in the country. Pythium isolates were obtained from soil samples, cocopeat bags, and cucumber roots collected from seven regions in the country. Identification of 80 Pythium isolates to the species level using sequences of the internal transcribed spacer region of the ribosomal RNA showed that they belong to four species: Pythium aphanidermatum (77 isolates), P. spinosum (1 isolate), P. myriotylum (1 isolate), and P. catenulatum (1 isolate). Investigating the aggressiveness of three Pythium spp. on cucumber showed that P. aphanidermatum, P. myriotylum, and P. spinosum are pathogenic. Phylogenetic analysis of P. aphanidermatum isolates showed that most of the isolates obtained from cocopeat clustered separately from isolates obtained from soil and roots. This may indicate a difference in the origin of the cocopeat isolates. Evaluating the resistance of 27 P. aphanidermatum isolates to hymexazol showed that most isolates were sensitive (0.9 to 31.2 mg liter−1) whereas one isolate was resistant (142.9 mg liter−1). This study is the first to report P. myriotylum and P. catenulatum in Oman. It is also the first to report the development of resistance to hymexazol among P. aphanidermatum populations from greenhouses. Growers should use integrated disease management strategies to avoid further development of resistance to hymexazol.

scholarly journals The response of soil and phyllosphere microbial communities to repeated application of the fungicide iprodione: accelerated biodegradation or toxicity?

2020 ◽  
Vol 96 (6) ◽  
Author(s):  
A Katsoula ◽  
S Vasileiadis ◽  
M Sapountzi ◽  
Dimitrios G Karpouzas
Keyword(s):  
Microbial Communities ◽  
Agricultural Production ◽  
Soil Microorganisms ◽  
Amplicon Sequencing ◽  
Fungal Communities ◽  
Similar Response ◽  
Repeated Application ◽  
Plant Leaves ◽  
Soil System ◽  
Plant Soil

ABSTRACT Pesticides interact with microorganisms in various ways with the outcome being negative or positive for the soil microbiota. Pesticides' effects on soil microorganisms have been studied extensively in soil but not in other pesticides-exposed microbial habitats like the phyllosphere. We tested the hypothesis that soil and phyllosphere support distinct microbial communities, but exhibit a similar response (accelerated biodegradation or toxicity) to repeated exposure to the fungicide iprodione. Pepper plants received four repeated foliage or soil applications of iprodione, which accelerated its degradation in soil (DT50_1st = 1.23 and DT50_4th = 0.48 days) and on plant leaves (DT50_1st > 365 and DT50_4th = 5.95 days). The composition of the epiphytic and soil bacterial and fungal communities, determined by amplicon sequencing, was significantly altered by iprodione. The archaeal epiphytic and soil communities responded differently; the former showed no response to iprodione. Three iprodione-degrading Paenarthrobacter strains were isolated from soil and phyllosphere. They hydrolyzed iprodione to 3,5-dichloraniline via the formation of 3,5-dichlorophenyl-carboxiamide and 3,5-dichlorophenylurea-acetate, a pathway shared by other soil-derived arthrobacters implying a phylogenetic specialization in iprodione biotransformation. Our results suggest that iprodione-repeated application could affect soil and epiphytic microbial communities with implications for the homeostasis of the plant–soil system and agricultural production.

scholarly journals Different Amplicon Targets for Sequencing-Based Studies of Fungal Diversity

2017 ◽  
Vol 83 (17) ◽  
Author(s):  
Francesca De Filippis ◽  
Manolo Laiola ◽  
Giuseppe Blaiotta ◽  
Danilo Ercolini
Keyword(s):  
Microbial Ecology ◽  
High Throughput ◽  
Biological Samples ◽  
Fungal Diversity ◽  
High Throughput Sequencing ◽  
Amplicon Sequencing ◽  
Fungal Species ◽  
Fungal Communities ◽  
Its2 Region ◽  
Mock Community

ABSTRACT Target-gene amplicon sequencing is the most exploited high-throughput sequencing application in microbial ecology. The targets are taxonomically relevant genes, with 16S rRNA being the gold standard for bacteria. As for fungi, the most commonly used target is the internal transcribed spacer (ITS). However, the uneven ITS length among species may promote preferential amplification and sequencing and incorrect estimation of their abundance. Therefore, the use of different targets is desirable. We evaluated the use of three different target amplicons for the characterization of fungal diversity. After an in silico primer evaluation, we compared three amplicons (the ITS1-ITS2 region [ITS1-2], 18S ribosomal small subunit RNA, and the D1/D2 domain of the 26S ribosomal large subunit RNA), using biological samples and a mock community of common fungal species. All three targets allowed for accurate identification of the species present. Nevertheless, high heterogeneity in ITS1-2 length was found, and this caused an overestimation of the abundance of species with a shorter ITS, while both 18S and 26S amplicons allowed for more reliable quantification. We demonstrated that ITS1-2 amplicon sequencing, although widely used, may lead to an incorrect evaluation of fungal communities, and efforts should be made to promote the use of different targets in sequencing-based microbial ecology studies. IMPORTANCE Amplicon-sequencing approaches for fungi may rely on different targets affecting the diversity and abundance of the fungal species. An increasing number of studies will address fungal diversity by high-throughput amplicon sequencing. The description of the communities must be accurate and reliable in order to draw useful insights and to address both ecological and biological questions. By analyzing a mock community and several biological samples, we demonstrate that using different amplicon targets may change the results of fungal microbiota analysis, and we highlight how a careful choice of the target is fundamental for a thorough description of the fungal communities.

scholarly journals Fungi in Permafrost-Affected Soils of the Canadian Arctic: Horizon- and Site-Specific Keystone Taxa Revealed by Co-Occurrence Network

2021 ◽  
Vol 9 (9) ◽  
pp. 1943
Author(s):  
Milan Varsadiya ◽  
Tim Urich ◽  
Gustaf Hugelius ◽  
Jiří Bárta
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Plant Pathogens ◽  
Close Contact ◽  
Relative Proportion ◽  
Canadian Arctic ◽  
Clustering Coefficient ◽  
Fungal Communities ◽  
Soil Horizon ◽  
Internal Transcribed Spacer Region

Permafrost-affected soil stores a significant amount of organic carbon. Identifying the biological constraints of soil organic matter transformation, e.g., the interaction of major soil microbial soil organic matter decomposers, is crucial for predicting carbon vulnerability in permafrost-affected soil. Fungi are important players in the decomposition of soil organic matter and often interact in various mutualistic relationships during this process. We investigated four different soil horizon types (including specific horizons of cryoturbated soil organic matter (cryoOM)) across different types of permafrost-affected soil in the Western Canadian Arctic, determined the composition of fungal communities by sequencing (Illumina MPS) the fungal internal transcribed spacer region, assigned fungal lifestyles, and by determining the co-occurrence of fungal network properties, identified the topological role of keystone fungal taxa. Compositional analysis revealed a significantly higher relative proportion of the litter saprotroph Lachnum and root-associated saprotroph Phialocephala in the topsoil and the ectomycorrhizal close-contact exploring Russula in cryoOM, whereas Sites 1 and 2 had a significantly higher mean proportion of plant pathogens and lichenized trophic modes. Co-occurrence network analysis revealed the lowest modularity and average path length, and highest clustering coefficient in cryoOM, which suggested a lower network resistance to environmental perturbation. Zi-Pi plot analysis suggested that some keystone taxa changed their role from generalist to specialist, depending on the specific horizon concerned, Cladophialophora in topsoil, saprotrophic Mortierella in cryoOM, and Penicillium in subsoil were classified as generalists for the respective horizons but specialists elsewhere. The litter saprotrophic taxon Cadophora finlandica played a role as a generalist in Site 1 and specialist in the rest of the sites. Overall, these results suggested that fungal communities within cryoOM were more susceptible to environmental change and some taxa may shift their role, which may lead to changes in carbon storage in permafrost-affected soil.

scholarly journals UNCROSS: Filtering of high-frequency cross-talk in 16S amplicon reads

2016 ◽  
Author(s):  
Robert C. Edgar
Keyword(s):  
Ribosomal Rna ◽  
Cross Talk ◽  
High Frequency ◽  
Biological Diversity ◽  
Illumina Miseq ◽  
Amplicon Sequencing ◽  
Illumina Gaiix ◽  
Microbial Metagenomics ◽  
Tumor Sequencing ◽  
Rna I

AbstractNext-generation amplicon sequencing is widely used for surveying biological diversity in applications such as microbial metagenomics, immune system repertoire analysis and targeted tumor sequencing of cancer-associated genes. In such studies, assignment of reads to incorrect samples (cross-talk) is a well-documented problem that is rarely considered in practice. By considering unexpected OTUs in artificial (mock) samples, I estimate that cross-talk occurred for ~2% of the reads in one Illumina GAIIx run and eleven Illumina MiSeq runs targeting 16S ribosomal RNA. I also describe UNCROSS, an algorithm for detecting and filtering cross-talk in OTU tables.

Amanita mansehraensis, a new species in section Vaginatae from Pakistan

Phytotaxa ◽  
2019 ◽  
Vol 409 (4) ◽  
pp. 189-201 ◽  
Author(s):  
MALKA SABA ◽  
DANNY HAELEWATERS ◽  
MUHAMMAD FIAZ ◽  
ABDUL NASIR KHALID ◽  
DONALD H. PFISTER
Keyword(s):  
New Species ◽  
Ribosomal Rna ◽  
Internal Transcribed Spacer ◽  
Sequence Data ◽  
Large Subunit ◽  
Pine Forests ◽  
Evolutionary Relationships ◽  
Internal Transcribed Spacer Region ◽  
Bayesian Inferences ◽  
A New Species

A new species of Amanita subgenus Amanita sect. Vaginatae is described and illustrated based on material collected in pine forests in district Mansehra, Khyber Pakhtoonkhaw, Pakistan. Amanita mansehraensis is recognized by the presence of a light brown or light greyish olive pileus with strong brown or deep brown pileus center; non-appendiculate, rimose, sulcate or plicate striate pileus margin; subglobose to ellipsoid basidiospores; and a saccate volva. The internal transcribed spacer region (ITS) and large subunit of the nuclear ribosomal RNA gene (nrLSU) were used for the delimitation of this species based on sequence data. The evolutionary relationships of A. mansehraensis with other species of Amanita were inferred by means of Maximum Likelihood and Bayesian inferences of the nrLSU dataset and concatenated ITS+nrLSU dataset. Amanita mansehraensis is most closely related to A. brunneofuliginea, A. pseudovaginata, and the recently described A. glarea.

scholarly journals Crop, genotype, and field environmental conditions shape bacterial and fungal seed epiphytic microbiomes

2020 ◽  
pp. 1-13
Author(s):  
Zayda P. Morales Moreira ◽  
Bobbi L. Helgason ◽  
James J. Germida
Keyword(s):  
Environmental Conditions ◽  
Amplicon Sequencing ◽  
Fungal Communities ◽  
Plant Fitness ◽  
Microbial Composition ◽  
Core Microbiome ◽  
Reproductive Structures ◽  
Microbial Assemblage ◽  
Crop Type ◽  
Diversity Structure

Seeds are reproductive structures able to carry and transfer microorganisms that play an important role in plant fitness. Genetic and external factors are reported to be partly responsible for the plant microbiome assemblage, but their contribution in seeds is poorly understood. In this study, wheat, canola, and lentil seeds were analyzed to characterize diversity, structure, and persistence of seed-associated microbial communities. Five lines and 2 generations of each crop were subjected to high-throughput amplicon sequencing of the 16S rRNA and internal transcribed spacer (ITS) regions. Bacterial and fungal communities differed most by crop type (30% and 47% of the variance), while generation explained an additional 10% and 15% of the variance. The offspring (i.e., generation harvested in 2016 at the same location) exhibited a higher number of common amplicon sequence variants (ASVs) and less variability in microbial composition. Additionally, in every sample analyzed, a “core microbiome” was detected consisting of 5 bacterial and 12 fungal ASVs. Our results suggest that crop, genotype, and field environmental conditions contributed to the seed-associated microbial assemblage. These findings not only expand our understanding of the factors influencing the seed microbiome but may also help us to manipulate and exploit the microbiota naturally carried by seeds.

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