Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We inv...Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We investigated the diversity and composition of epiphytic bacteria from two common submerged macrophytes: Vallisneria natans and Hydrilla verticillata in Taihu Lake, Jiangsu, China, using methods of terminal restriction fragment length polymorphisms (T-RFLP) and clone library analyses targeted at bacterial 16S rRNA genes. The results show that: (1) the libraries of the two waterweeds contain wide phylogenetic distribution of bacteria, and that the sequences of the two libraries can be separated into 93 OTUs (at 97% similar value); (2) Betaproteobacteria, including Burkholderiales, was the most abundant bacterial group on both plants. Cyanobacteria and Gammaproteobacteria were the second largest groups on V. natans and H. verticillata, respectively. Both clone libraries included some sequences related to those of methanotrophs and nitrogen-fixing bacteria; (3) Cluster analysis of the T-RFLP profiles showed two distinct clusters corresponding to the two plant populations. Both ANOSIM of the T-RFLP data and Libshuff analysis of the two clone libraries indicated a significant difference in epiphytic bacterial communities between the two plants. Therefore, the epiphytic bacterial communities on submerged macrophytes appear to be diverse and host-specific, which may aid in understanding the ecological functions of submerged macrophytes in general.展开更多
Phyllosphere microorganisms are a crucial component of environmental microorganisms,highly influenced by host characteristics,and play a significant role in plant health and productivity.Nonetheless,the impact of host...Phyllosphere microorganisms are a crucial component of environmental microorganisms,highly influenced by host characteristics,and play a significant role in plant health and productivity.Nonetheless,the impact of host characteristics on shaping phyllosphere microbial communities of plants with different life forms remains ambiguous.Utilizing high-throughput sequencing technology,this study analyzed the diversity and community composition of phyllosphere epiphytic microorganisms(e.g.,bacteria and fungi)of various plant life forms in the hinterland of the Gurbantunggut Desert,Northwest China.Functional annotation of prokaryotic taxa(FAPROTAX)and fungi function guild(FUNGuild)were employed to assess the ecological functions of microorganisms and to investigate the role of stochastic and deterministic processes in shaping phyllosphere microbial communities.Result showed a diverse array of phyllosphere epiphytic microorganisms in the desert plants,with Proteobacteria,Cyanobacteria,and Actinobacteriota dominating bacterial community,while Ascomycota and Basidiomycota were prevalent in fungal community.Comparison across different plant life forms highlighted distinct microbial communities,indicating strong filtering effects by plant characteristics.FAPROTAX prediction identified intracellular parasites(accounting for 27.44%of bacterial community abundance),chemoheterotrophy(10.12%),and phototrophy(17.41%)as the main functions of epiphytic bacteria on leaves of different life form plants.FUNGuild prediction indicated that phyllosphere epiphytic fungi primarily served as Saprotrophs(81.77%),Pathotrophs(17.41%),and Symbiotrophs(0.82%).Co-occurrence network analysis demonstrated a predominance of positive correlations among different microbial taxa.Raup-Crick dissimilarity index analysis revealed that deterministic processes predominantly influenced phyllosphere bacterial and fungal community assembly.Variance partitioning analysis and random forest modeling suggested that plant leaf functional traits significantly impacted展开更多
To explore how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes,the submerged plant Myriophyllum spicatum was exposed to cell extracts from microcystin(MC)-and non-MC-producing Microc...To explore how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes,the submerged plant Myriophyllum spicatum was exposed to cell extracts from microcystin(MC)-and non-MC-producing Microcystis strains in a laboratory experiment.Results showed that both Mcracystis cell extracts exerted obvious damages to plant biomass,photosynthesis,primary and secondary metabolism measures,and resistance of plant antioxidant systems,with MC-producing Microcystis having stronger effects due to the presence of MCs.Cyanotoxins other than MCs responsible for the negative effects from both strains needs further identification.The Shannon diversity and Chao1 indices of epiphytic and planktonic bacteria were decreased by the cell extracts from both Microcystis strains.However,epiphytic and planktonic bacterial communities responded differently to cell extracts at the genus level.The dominant genera of planktonic bacteria including Enterobacter,Pseudomonas,and Novosphingobium from phylum Proteobacteria,Chryseobacterium from phylum Bacteroidetes,and Microbacterium from Actinobacteriota in the treatments with cell extracts were previously reported to have strains with algicidal and MC-degrading capabilities.B acterial genes associated with energy production and conversion,amino acid transport and metabolism,and inorganic ion transport and metabolism,were more abundant in both treatments than the control for planktonic bacteria,but less abundant for epiphytic bacteria.We speculate that planktonic bacterial communities have the potential to use and degrade substances derived from Microcystis cell extracts,which may be beneficial for M.spicatum to alleviate damages from Microcystis.Further research is needed to verify the structure and function dynamics of epiphytic and planktonic bacteria in the interaction between cyanobacteria and submerged macrophytes.展开更多
The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） Wha...The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） What is the ecological niche of the different epiphytic orchid species？ （2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.展开更多
The economic alga Neopyropia,which holds significant value in China for its edibility and economic potential,harbors diverse epiphytic bacteria on its surface.The epiphytic bacteria on Neopyropia yezoensis and Neopyro...The economic alga Neopyropia,which holds significant value in China for its edibility and economic potential,harbors diverse epiphytic bacteria on its surface.The epiphytic bacteria on Neopyropia yezoensis and Neopyropia katadae,two nori species of Neopyropia living at the same tidal level but with distinct physiological states and living habits,were investigated to understand the differences between them and the effects of epiphytic bacteria on their differential characteristics.Analysis of 16S rRNA gene sequences and real-time quantitative PCR(qPCR)of thalli and seawater samples(n=24)revealed notable differences in microbial diversity and community structure between the two species.Bacteroidetes dominated the bacterial communities in association with N.yezoensis,whereas Proteobacteria were predominant in N.katadae.Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt2)analysis revealed enriched genes that related to the ABC transport system,iron complex outer membrane receptor proteins,and proliferation in N.yezoensis,whereas N.katadae exhibited enrichment of genes that related to energy supply as well as cell wall and cell membrane production.The results of qPCR indicate a higher abundance of epiphytic bacteria on surface of N.yezoensis than those on surface of N.katadae.The findings indicate that differences in the living environments of N.yezoensis and N.katadae may result in distinct structural composition and abundance of epiphytic bacteria on their surfaces,thereby conferring specific biological functionalities to each microbial community,and the epiphytic bacteria may shape the living habits of hosts to some extents.This study provided a basis for understanding the close association between surface microorganisms and algal bodies,and the physiological and ecological characteristics of nori species.展开更多
Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes i...Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms.Epiphytic biofilms were collected from submerged macrophytes(Patamogeton lucens and Najas marina L.)in the Caohai Lake,Guizhou,SW China,from July to November 2020 to:(1)investigate the impact of abiotic and biotic variables on denitrifying bacterial communities;(2)investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks;and(3)determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities.Abiotic and biotic factors influenced the variation in the denitrifying bacterial community,as shown in the Mantel test.The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria.Denitrifying bacterial community co-occurrence network complexity(larger average degrees representing stronger network complexity)increased continuously from July to September and decreased in October before increasing in November.The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November.The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP),pH,and water temperature(WT),according to the ordinary least-squares(OLS)model.The modified stochasticity ratio(MST)results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities.The influence of environmental variables to denitrifying bacterial communities,as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities,were discovered in epiphytic biofilms in this study.The findings could aid in the appropriate understanding and use of epiphytic biofilms denitr展开更多
We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses.Twelve strains of bacteria were obtained from the surfaces of the following four sp...We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses.Twelve strains of bacteria were obtained from the surfaces of the following four species of algae:Gracilaria textorii,Ulva pertusa,Laminaria japonica,and Polysiphonia urceolata.The isolated strains of bacteria can be divided into two groups:Halomonas and Vibrio,in physiology,biochemical characteristics and 16S rDNA sequence analyses.The phylogenetic tree constructed based on 16S rDNA sequences of the isolates shows four obvious clusters,Halomonas venusta,Vibrio tasmaniensis,Vibrio lentus,and Vibrio splendidus.Isolates from the surface of P.urceolata are more abundant and diverse,of which strains P9 and P28 have a 16S rDNA sequence very similar(97.5%-99.8%) to that of V.splendidus.On the contrary,the isolates from the surfaces of G.textorii,U.pertusa and L.japonica are quite simple and distribute on different branches of the phylogenetic tree.In overall,the results of this study indicate that the genetic relationships among the isolates are quite close and display a certain level of host species specificity,and alga-associated bacteria species are algal species specific.展开更多
Mango anthracnose disease forms typical irregular-shaped black necrotic spots on the fruit peel of mature fruit and is caused by <i>Colletotrichum gloeosporioides</i>. In order to improve the disease contr...Mango anthracnose disease forms typical irregular-shaped black necrotic spots on the fruit peel of mature fruit and is caused by <i>Colletotrichum gloeosporioides</i>. In order to improve the disease control with a limited use of fungicides, new microbial agents able to limit the growth of the pathogen were searched in the indigenous natural flora of mango surface. In order to find a suitable biocontrol agent, a screening was applied to 305 epiphytic bacteria isolated from the carposphere of 17 mango cultivars sampled from eight locations on Reunion Island. The screening approach involved a first step based on the ability of the isolates to form a biofilm, to grow under fruit storage conditions, and to interfere with the development of <i>C. gloeosporioides</i>. In a second step, the capability of selected isolates to limit <i>C. gloeosporioides in vitro</i> mycelial growth and conidia germination was assessed and species identified. The most effective bacteria belonged to the <i>Enterobacter</i>, <i>Pantoea</i>, <i>Kosakonia</i> and <i>Leuconostoc</i> genera, but for some of them, their safe use has to be demonstrated. Efficacy <i>in vivo</i>, performed on wounded mature mango fruit, was limited, probably because of the wounding inoculation strategy favoring the pathogen. Future biocontrol treatments should focus on preharvest applications to enhance the protective benefit.展开更多
Denitrifying bacteria are a crucial component of aquatic ecosystem in nitrogen cycle.However,the denitrifying bacterial community dynamics and structure in epiphytic biofilms remain unexplored.The abundance of denitri...Denitrifying bacteria are a crucial component of aquatic ecosystem in nitrogen cycle.However,the denitrifying bacterial community dynamics and structure in epiphytic biofilms remain unexplored.The abundance of denitrification gene(nir)and structure of nirS-denitrifying bacterial community in the epiphytic biofilms collected in July and November of 2018 from a typical plateau lake(Caohai Wetland,Guizhou,China)were studied by Real-time Quantitative Polymerase Chain Reaction(qPCR)and highthroughput sequencing.Results show that the gene abundance of nirK was higher than that of nirS(P<0.05),and it was significantly different during the growth period(July)than the decline period(November).The denitrifying bacterial species was similar in the two months and shared 76.18%of OTUs.Proteobacteria(56.55%±22.15%)was the dominant phylum in all the samples.Epiphytic biofilms between growth period and decline period displayed significantly different microbial community structures due to differences in species abundance.Water temperature was the crucial factor that affected the denitrifying microbial community structure in our study.Environmental factors explain only partially the dynamic characteristics of denitrifying microbial communities,implying that the stochastic processes affected the construction of denitrifying microbial communities.As the null model analysis results show,dispersal limitation(stochastic)and undominated processes significantly influenced the assembly of denitrifying microbial communities.This study broadened our understanding of the denitrifying bacterial community structure and its function on epiphytic biofilms in freshwater ecosystems with new information provided.展开更多
The established culture of gametophytes of the red alga Pyropia yezoensis (TU-1) is superficially colonized by epiphytic bacteria. By 16S rRNA sequencing, 6 bacterial species were identified, and a culturable bacteriu...The established culture of gametophytes of the red alga Pyropia yezoensis (TU-1) is superficially colonized by epiphytic bacteria. By 16S rRNA sequencing, 6 bacterial species were identified, and a culturable bacterium, Neptunomonas sp. BPy-1, was isolated. The 16S rRNA sequences of BPy-1 showed 100% identity with that of Neptunomonas sp. 0536, a probiotic bacterium found in greenshell mussels in New Zealand. Physiological tests revealed that 22 characters were identical between BPy-1 and 0536, but that 4 characters differed. BPy-1 cannot grow in the artificial seawater used for the culture of gametophytes. BPy-1 can grow in the artificial seawater with ethanol or butanol but not in methanol or propanol. To determine the effect of BPy-1 on gametophyte growth, BPy-1 colonization was reduced by 80% using a multi-enzyme cleaner. Changing the cleaner concentration yielded two types of gametophytes, a compressed or callus-like form and a nearly normal form. BPy-1 promoted the growth of the treated gametophytes with relatively normal form, while it showed less effect on compressed gametophytes. These findings suggested that BPy-1 promotes the growth of damaged gametophytes but does not affect the development of normal gametophytes.展开更多
Rhynchostegium megapolitanum was observed during a study of the effects of the invasive nonnative Rosa rugosa in a sand dune. The vascular as well as the epiphytic and epigeic cryptogam vegetation was recorded., and s...Rhynchostegium megapolitanum was observed during a study of the effects of the invasive nonnative Rosa rugosa in a sand dune. The vascular as well as the epiphytic and epigeic cryptogam vegetation was recorded., and soil properties were measured. Epihytic lichens were abundant on dead or dying branches of Rosa rugosa scrubs, under which the stable substrate and high light exposure provided growth conditions for an epigeic community dominated by lichens and bryophytes. The occurrence of the rare bryophyte Rhynchostegium megapolitanum is discussed.展开更多
The bryophytic vegetation associated with Platanus orientalis trees were studied and compared with other important tree species of Nainital. In total 27 mosses and liverworts belonging to 14 families with three morpho...The bryophytic vegetation associated with Platanus orientalis trees were studied and compared with other important tree species of Nainital. In total 27 mosses and liverworts belonging to 14 families with three morphological groups formed the principle component of Platanus orientalis tree bark. Based on IVI (Important Value Index), Regmatodon orthostegius together with Brachymenium capitulatum formed the pioneer community, while Herpetineuron toccoae formed the climax community on the Platanus orientalis stems. Comparison of the bryoflora of P. orientalis with other dominant trees of this locality indicated that 15 species were common, while 12 species viz., Didymodon vinealis (Brid.) R.H., Bryoerythrophyllum dentatum (Mitt.) Chen, Gemmabryum apiculatum (Schw?gr.), Ditrichum heteromallum (Hedw.) Britt., Entodon chloropus Ren. & Card., Cylindrothecium laetum (Griff.) Paris, Fabronia schensiana C. Muell., Lejeunea tuberculosa Stephani, Levierella neckeroides (Griff.), Regmatodon orthostegius Mont., Rhynchostegiella menadensis (Lac.) Bartr. and Stereophyllum fulvum (Harv.) Jaeg. were confined to the tree barks of P. orientalis.展开更多
Tara (Caesalpinia spinose Molina Kuntz) is a native plant of the Bolivian Andes. A number of projects have promoted the cultivation of this species over the last 20 years, in efforts to make use of its medicinal, food...Tara (Caesalpinia spinose Molina Kuntz) is a native plant of the Bolivian Andes. A number of projects have promoted the cultivation of this species over the last 20 years, in efforts to make use of its medicinal, food and industrial properties. However, as tara plantations have grown, so too has the incidence of disease affecting the species, leading to economic losses. The aim of the present work was to identify the causal agent of wilting in tara, and to determine the incidence of the disease in nursery-grown plants. Three experimental plots (R1-R3) were established in plantlet production bedsat the ESFOR nursery in order to assess the incidence of wilting. Plant spacing was 1 × 1 m. At the two leaf stage, samples of diseased and apparently healthy plants were taken to the laboratory for the isolation of pathogens. Both the apparently healthy and diseased plants gave rise to the same kinds of fungal colony on PDA. Microscopic examination revealed microconidia, macroconidia, phialides and chlamydospores suggesting the causal agent to be Fusarium oxysporum. Over the (up to) 84-day period following thinning, the incidence of wilting for 2010 was R1 = 2.56%, R2 = 3.15% and R3 = 2.22% per 14 days, and for 2013 it was R1 = 1.24%, R2 = 2.45% and R3 = 2.13% per 14 days;the apparent infection rates for 2010 were rR1 = 0.0003/day, rR2 = 0.0003/day and rR3 = 0.0003/day, and for 2013 they were rR1 = 0.0003/day, rR2 = 0.0004/day and rR3 = 0.0003/day. These values are characteristic of monocyclic epiphytic fungi such as F. oxysporum.展开更多
The Graeco-Roman harbor of Neapolis (Naples, Italy), chronologically constrained between the late 4th century BC and the 6th century AD, offers a unique sight on relationship between past and present into the history ...The Graeco-Roman harbor of Neapolis (Naples, Italy), chronologically constrained between the late 4th century BC and the 6th century AD, offers a unique sight on relationship between past and present into the history of the marine biodiversity. In fact, the digs expose fossil leaf of Posidonia oceanica with epiphytic communities of microorganisms. Posidonia oceanica is a seagrass endemic to theMediterraneanthat forms large meadows whose remains can persist in the sediment for thousands of years. In this communication, we report results of analyses carried out using both molecular and morphological techniques on sub-fossil leaves of P. oceanica and their associated epiphytic communities.展开更多
We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, ...We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be pla展开更多
基金Supported by the National Natural Science Foundation of China(No.40730528)the National Basic Research Program of China(973Program)(No.2008CB418104)+2 种基金the Knowledge Innovation Project of Chinese Academy of Sciences(No.KZCX2-YW-JC302)the Jiangsu Provincial Science Foundation(No.BK2009024)the Frontier Foundation of Nanjing Institute of Geography & Limnology,Chinese Academy of Sciences(No.09SL021001)
文摘Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We investigated the diversity and composition of epiphytic bacteria from two common submerged macrophytes: Vallisneria natans and Hydrilla verticillata in Taihu Lake, Jiangsu, China, using methods of terminal restriction fragment length polymorphisms (T-RFLP) and clone library analyses targeted at bacterial 16S rRNA genes. The results show that: (1) the libraries of the two waterweeds contain wide phylogenetic distribution of bacteria, and that the sequences of the two libraries can be separated into 93 OTUs (at 97% similar value); (2) Betaproteobacteria, including Burkholderiales, was the most abundant bacterial group on both plants. Cyanobacteria and Gammaproteobacteria were the second largest groups on V. natans and H. verticillata, respectively. Both clone libraries included some sequences related to those of methanotrophs and nitrogen-fixing bacteria; (3) Cluster analysis of the T-RFLP profiles showed two distinct clusters corresponding to the two plant populations. Both ANOSIM of the T-RFLP data and Libshuff analysis of the two clone libraries indicated a significant difference in epiphytic bacterial communities between the two plants. Therefore, the epiphytic bacterial communities on submerged macrophytes appear to be diverse and host-specific, which may aid in understanding the ecological functions of submerged macrophytes in general.
基金the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01A351)the Joint Fund of National Natural Science Foundation of China(U2003214)+1 种基金the Key Project of Xinjiang Uygur Autonomous Region Natural Science Foundation(2022D01D083)the Tianchi Talent Introduction Project of Xinjiang Uygur Autonomous Region.We thank Mr.LI Yonggang,Mrs.DU Fang,Mrs.SHEN Hui,Mrs.PAN Qi,and Mrs.MENG Huanhuan for providing help with the experiment in the field.
文摘Phyllosphere microorganisms are a crucial component of environmental microorganisms,highly influenced by host characteristics,and play a significant role in plant health and productivity.Nonetheless,the impact of host characteristics on shaping phyllosphere microbial communities of plants with different life forms remains ambiguous.Utilizing high-throughput sequencing technology,this study analyzed the diversity and community composition of phyllosphere epiphytic microorganisms(e.g.,bacteria and fungi)of various plant life forms in the hinterland of the Gurbantunggut Desert,Northwest China.Functional annotation of prokaryotic taxa(FAPROTAX)and fungi function guild(FUNGuild)were employed to assess the ecological functions of microorganisms and to investigate the role of stochastic and deterministic processes in shaping phyllosphere microbial communities.Result showed a diverse array of phyllosphere epiphytic microorganisms in the desert plants,with Proteobacteria,Cyanobacteria,and Actinobacteriota dominating bacterial community,while Ascomycota and Basidiomycota were prevalent in fungal community.Comparison across different plant life forms highlighted distinct microbial communities,indicating strong filtering effects by plant characteristics.FAPROTAX prediction identified intracellular parasites(accounting for 27.44%of bacterial community abundance),chemoheterotrophy(10.12%),and phototrophy(17.41%)as the main functions of epiphytic bacteria on leaves of different life form plants.FUNGuild prediction indicated that phyllosphere epiphytic fungi primarily served as Saprotrophs(81.77%),Pathotrophs(17.41%),and Symbiotrophs(0.82%).Co-occurrence network analysis demonstrated a predominance of positive correlations among different microbial taxa.Raup-Crick dissimilarity index analysis revealed that deterministic processes predominantly influenced phyllosphere bacterial and fungal community assembly.Variance partitioning analysis and random forest modeling suggested that plant leaf functional traits significantly impacted
基金Supported by the National Program for the Introduction of High-end Foreign Experts(No.G2021026024L)the National Natural Science Foundation of China(Nos.31700405,U1904124)+1 种基金the Major Public Welfare Projects in Henan Province(No.201300311300)the Breeding Project of Henan Normal University(No.HNU2021PL05)。
文摘To explore how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes,the submerged plant Myriophyllum spicatum was exposed to cell extracts from microcystin(MC)-and non-MC-producing Microcystis strains in a laboratory experiment.Results showed that both Mcracystis cell extracts exerted obvious damages to plant biomass,photosynthesis,primary and secondary metabolism measures,and resistance of plant antioxidant systems,with MC-producing Microcystis having stronger effects due to the presence of MCs.Cyanotoxins other than MCs responsible for the negative effects from both strains needs further identification.The Shannon diversity and Chao1 indices of epiphytic and planktonic bacteria were decreased by the cell extracts from both Microcystis strains.However,epiphytic and planktonic bacterial communities responded differently to cell extracts at the genus level.The dominant genera of planktonic bacteria including Enterobacter,Pseudomonas,and Novosphingobium from phylum Proteobacteria,Chryseobacterium from phylum Bacteroidetes,and Microbacterium from Actinobacteriota in the treatments with cell extracts were previously reported to have strains with algicidal and MC-degrading capabilities.B acterial genes associated with energy production and conversion,amino acid transport and metabolism,and inorganic ion transport and metabolism,were more abundant in both treatments than the control for planktonic bacteria,but less abundant for epiphytic bacteria.We speculate that planktonic bacterial communities have the potential to use and degrade substances derived from Microcystis cell extracts,which may be beneficial for M.spicatum to alleviate damages from Microcystis.Further research is needed to verify the structure and function dynamics of epiphytic and planktonic bacteria in the interaction between cyanobacteria and submerged macrophytes.
文摘The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） What is the ecological niche of the different epiphytic orchid species？ （2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.
基金Supported by the National Natural Science Foundation of China(Nos.42276148,41976133)。
文摘The economic alga Neopyropia,which holds significant value in China for its edibility and economic potential,harbors diverse epiphytic bacteria on its surface.The epiphytic bacteria on Neopyropia yezoensis and Neopyropia katadae,two nori species of Neopyropia living at the same tidal level but with distinct physiological states and living habits,were investigated to understand the differences between them and the effects of epiphytic bacteria on their differential characteristics.Analysis of 16S rRNA gene sequences and real-time quantitative PCR(qPCR)of thalli and seawater samples(n=24)revealed notable differences in microbial diversity and community structure between the two species.Bacteroidetes dominated the bacterial communities in association with N.yezoensis,whereas Proteobacteria were predominant in N.katadae.Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt2)analysis revealed enriched genes that related to the ABC transport system,iron complex outer membrane receptor proteins,and proliferation in N.yezoensis,whereas N.katadae exhibited enrichment of genes that related to energy supply as well as cell wall and cell membrane production.The results of qPCR indicate a higher abundance of epiphytic bacteria on surface of N.yezoensis than those on surface of N.katadae.The findings indicate that differences in the living environments of N.yezoensis and N.katadae may result in distinct structural composition and abundance of epiphytic bacteria on their surfaces,thereby conferring specific biological functionalities to each microbial community,and the epiphytic bacteria may shape the living habits of hosts to some extents.This study provided a basis for understanding the close association between surface microorganisms and algal bodies,and the physiological and ecological characteristics of nori species.
基金Supported by the National Natural Science Foundation of China(No.41867056)the Guizhou Provincial Key Technology R&D Program(Nos.2021470,2023216)。
文摘Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms.Epiphytic biofilms were collected from submerged macrophytes(Patamogeton lucens and Najas marina L.)in the Caohai Lake,Guizhou,SW China,from July to November 2020 to:(1)investigate the impact of abiotic and biotic variables on denitrifying bacterial communities;(2)investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks;and(3)determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities.Abiotic and biotic factors influenced the variation in the denitrifying bacterial community,as shown in the Mantel test.The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria.Denitrifying bacterial community co-occurrence network complexity(larger average degrees representing stronger network complexity)increased continuously from July to September and decreased in October before increasing in November.The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November.The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP),pH,and water temperature(WT),according to the ordinary least-squares(OLS)model.The modified stochasticity ratio(MST)results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities.The influence of environmental variables to denitrifying bacterial communities,as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities,were discovered in epiphytic biofilms in this study.The findings could aid in the appropriate understanding and use of epiphytic biofilms denitr
基金Supported by the National Natural Science Foundation of China (No 40376048)the National Basic Research Program of China (973 Program) (No 2006CB400604)
文摘We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses.Twelve strains of bacteria were obtained from the surfaces of the following four species of algae:Gracilaria textorii,Ulva pertusa,Laminaria japonica,and Polysiphonia urceolata.The isolated strains of bacteria can be divided into two groups:Halomonas and Vibrio,in physiology,biochemical characteristics and 16S rDNA sequence analyses.The phylogenetic tree constructed based on 16S rDNA sequences of the isolates shows four obvious clusters,Halomonas venusta,Vibrio tasmaniensis,Vibrio lentus,and Vibrio splendidus.Isolates from the surface of P.urceolata are more abundant and diverse,of which strains P9 and P28 have a 16S rDNA sequence very similar(97.5%-99.8%) to that of V.splendidus.On the contrary,the isolates from the surfaces of G.textorii,U.pertusa and L.japonica are quite simple and distribute on different branches of the phylogenetic tree.In overall,the results of this study indicate that the genetic relationships among the isolates are quite close and display a certain level of host species specificity,and alga-associated bacteria species are algal species specific.
文摘Mango anthracnose disease forms typical irregular-shaped black necrotic spots on the fruit peel of mature fruit and is caused by <i>Colletotrichum gloeosporioides</i>. In order to improve the disease control with a limited use of fungicides, new microbial agents able to limit the growth of the pathogen were searched in the indigenous natural flora of mango surface. In order to find a suitable biocontrol agent, a screening was applied to 305 epiphytic bacteria isolated from the carposphere of 17 mango cultivars sampled from eight locations on Reunion Island. The screening approach involved a first step based on the ability of the isolates to form a biofilm, to grow under fruit storage conditions, and to interfere with the development of <i>C. gloeosporioides</i>. In a second step, the capability of selected isolates to limit <i>C. gloeosporioides in vitro</i> mycelial growth and conidia germination was assessed and species identified. The most effective bacteria belonged to the <i>Enterobacter</i>, <i>Pantoea</i>, <i>Kosakonia</i> and <i>Leuconostoc</i> genera, but for some of them, their safe use has to be demonstrated. Efficacy <i>in vivo</i>, performed on wounded mature mango fruit, was limited, probably because of the wounding inoculation strategy favoring the pathogen. Future biocontrol treatments should focus on preharvest applications to enhance the protective benefit.
基金*Supported by the National Natural Science Foundation of China(No.41867056)the Joint Fund of the National Natural Science Foundation of China and the Karst Science Research Center of Guizhou Province(No.U1812401)+1 种基金the Guizhou Province Graduate Education Innovation Project(No.YJSCXJH(2019)048)the Science and Technology Support Project of Guizhou Province(No.2021470)。
文摘Denitrifying bacteria are a crucial component of aquatic ecosystem in nitrogen cycle.However,the denitrifying bacterial community dynamics and structure in epiphytic biofilms remain unexplored.The abundance of denitrification gene(nir)and structure of nirS-denitrifying bacterial community in the epiphytic biofilms collected in July and November of 2018 from a typical plateau lake(Caohai Wetland,Guizhou,China)were studied by Real-time Quantitative Polymerase Chain Reaction(qPCR)and highthroughput sequencing.Results show that the gene abundance of nirK was higher than that of nirS(P<0.05),and it was significantly different during the growth period(July)than the decline period(November).The denitrifying bacterial species was similar in the two months and shared 76.18%of OTUs.Proteobacteria(56.55%±22.15%)was the dominant phylum in all the samples.Epiphytic biofilms between growth period and decline period displayed significantly different microbial community structures due to differences in species abundance.Water temperature was the crucial factor that affected the denitrifying microbial community structure in our study.Environmental factors explain only partially the dynamic characteristics of denitrifying microbial communities,implying that the stochastic processes affected the construction of denitrifying microbial communities.As the null model analysis results show,dispersal limitation(stochastic)and undominated processes significantly influenced the assembly of denitrifying microbial communities.This study broadened our understanding of the denitrifying bacterial community structure and its function on epiphytic biofilms in freshwater ecosystems with new information provided.
文摘The established culture of gametophytes of the red alga Pyropia yezoensis (TU-1) is superficially colonized by epiphytic bacteria. By 16S rRNA sequencing, 6 bacterial species were identified, and a culturable bacterium, Neptunomonas sp. BPy-1, was isolated. The 16S rRNA sequences of BPy-1 showed 100% identity with that of Neptunomonas sp. 0536, a probiotic bacterium found in greenshell mussels in New Zealand. Physiological tests revealed that 22 characters were identical between BPy-1 and 0536, but that 4 characters differed. BPy-1 cannot grow in the artificial seawater used for the culture of gametophytes. BPy-1 can grow in the artificial seawater with ethanol or butanol but not in methanol or propanol. To determine the effect of BPy-1 on gametophyte growth, BPy-1 colonization was reduced by 80% using a multi-enzyme cleaner. Changing the cleaner concentration yielded two types of gametophytes, a compressed or callus-like form and a nearly normal form. BPy-1 promoted the growth of the treated gametophytes with relatively normal form, while it showed less effect on compressed gametophytes. These findings suggested that BPy-1 promotes the growth of damaged gametophytes but does not affect the development of normal gametophytes.
文摘Rhynchostegium megapolitanum was observed during a study of the effects of the invasive nonnative Rosa rugosa in a sand dune. The vascular as well as the epiphytic and epigeic cryptogam vegetation was recorded., and soil properties were measured. Epihytic lichens were abundant on dead or dying branches of Rosa rugosa scrubs, under which the stable substrate and high light exposure provided growth conditions for an epigeic community dominated by lichens and bryophytes. The occurrence of the rare bryophyte Rhynchostegium megapolitanum is discussed.
文摘The bryophytic vegetation associated with Platanus orientalis trees were studied and compared with other important tree species of Nainital. In total 27 mosses and liverworts belonging to 14 families with three morphological groups formed the principle component of Platanus orientalis tree bark. Based on IVI (Important Value Index), Regmatodon orthostegius together with Brachymenium capitulatum formed the pioneer community, while Herpetineuron toccoae formed the climax community on the Platanus orientalis stems. Comparison of the bryoflora of P. orientalis with other dominant trees of this locality indicated that 15 species were common, while 12 species viz., Didymodon vinealis (Brid.) R.H., Bryoerythrophyllum dentatum (Mitt.) Chen, Gemmabryum apiculatum (Schw?gr.), Ditrichum heteromallum (Hedw.) Britt., Entodon chloropus Ren. & Card., Cylindrothecium laetum (Griff.) Paris, Fabronia schensiana C. Muell., Lejeunea tuberculosa Stephani, Levierella neckeroides (Griff.), Regmatodon orthostegius Mont., Rhynchostegiella menadensis (Lac.) Bartr. and Stereophyllum fulvum (Harv.) Jaeg. were confined to the tree barks of P. orientalis.
文摘Tara (Caesalpinia spinose Molina Kuntz) is a native plant of the Bolivian Andes. A number of projects have promoted the cultivation of this species over the last 20 years, in efforts to make use of its medicinal, food and industrial properties. However, as tara plantations have grown, so too has the incidence of disease affecting the species, leading to economic losses. The aim of the present work was to identify the causal agent of wilting in tara, and to determine the incidence of the disease in nursery-grown plants. Three experimental plots (R1-R3) were established in plantlet production bedsat the ESFOR nursery in order to assess the incidence of wilting. Plant spacing was 1 × 1 m. At the two leaf stage, samples of diseased and apparently healthy plants were taken to the laboratory for the isolation of pathogens. Both the apparently healthy and diseased plants gave rise to the same kinds of fungal colony on PDA. Microscopic examination revealed microconidia, macroconidia, phialides and chlamydospores suggesting the causal agent to be Fusarium oxysporum. Over the (up to) 84-day period following thinning, the incidence of wilting for 2010 was R1 = 2.56%, R2 = 3.15% and R3 = 2.22% per 14 days, and for 2013 it was R1 = 1.24%, R2 = 2.45% and R3 = 2.13% per 14 days;the apparent infection rates for 2010 were rR1 = 0.0003/day, rR2 = 0.0003/day and rR3 = 0.0003/day, and for 2013 they were rR1 = 0.0003/day, rR2 = 0.0004/day and rR3 = 0.0003/day. These values are characteristic of monocyclic epiphytic fungi such as F. oxysporum.
文摘The Graeco-Roman harbor of Neapolis (Naples, Italy), chronologically constrained between the late 4th century BC and the 6th century AD, offers a unique sight on relationship between past and present into the history of the marine biodiversity. In fact, the digs expose fossil leaf of Posidonia oceanica with epiphytic communities of microorganisms. Posidonia oceanica is a seagrass endemic to theMediterraneanthat forms large meadows whose remains can persist in the sediment for thousands of years. In this communication, we report results of analyses carried out using both molecular and morphological techniques on sub-fossil leaves of P. oceanica and their associated epiphytic communities.
文摘We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be pla
