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1.
J Agric Food Chem ; 70(46): 14693-14705, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36350271

RESUMO

Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (X. citri), is a plant disease affecting Citrus crops worldwide. However, little is known about defense compounds in Citrus. Here, we conducted a mass spectrometry-based metabolomic approach to obtain an overview of the chemical responses of Citrus leaves to X. citri infection. To facilitate result interpretation, the multivariate analyses were combined with molecular networking to identify biomarkers. Metabolite variations among untreated and X. citri-inoculated Citrus samples under greenhouse conditions highlighted induced defense biomarkers. Notably, the plant tryptophan metabolism pathway was activated, leading to the accumulation of N-methylated tryptamine derivatives. This finding was subsequently confirmed in symptomatic leaves in the field. Several tryptamine derivatives showed inhibitory effects in vitro against X. citri. This approach has enabled the identification of new chemically related biomarker groups and their dynamics in the response of Citrus leaves to Xanthomonas infection.


Assuntos
Citrus sinensis , Citrus , Xanthomonas , Citrus sinensis/microbiologia , Doenças das Plantas/microbiologia , Citrus/microbiologia , Folhas de Planta/microbiologia , Triptaminas/farmacologia
2.
Int J Mol Sci ; 23(21)2022 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-36362319

RESUMO

Sugarcane leaf scald is a systemic disease caused by Xanthomonas albilineans that limits sugarcane yield and quality. Previous research has shown that exogenous application of copper hydroxide to plants is effective in controlling this disease. However, long-term bactericide use causes serious "3R" problems: resistance, resurgence, and residue. It is therefore urgent to discover new methods for the improvement of bactericide efficiency and efficacy. In the present study, disease index values for leaf scald were measured in sugarcane seedlings over time to determine the effects of different concentrations of copper hydroxide, types of silicon additive, and treatment timing after inoculation with X. albilineans on controlling sugarcane leaf scald disease. Our results show copper hydroxide mixed with organosilicon additive could improve the bactericide efficiency and efficacy and reduce the growth of pathogenic bacteria, even at a reduced concentration in both laboratory and field conditions. This study provides an important practical model for controlling sugarcane leaf scald disease by reducing the concentration of bactericide and increasing its efficacy in sugarcane fields.


Assuntos
Saccharum , Xanthomonas , Saccharum/microbiologia , Folhas de Planta/microbiologia
3.
PLoS One ; 17(10): e0275845, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36223398

RESUMO

Many endophytic fungi have the potential to function as saprotrophs when living host tissues senesce and enter the litter pool. The consumption of plant litter by fungi obviously requires moisture but, in the arid, western USA, the native range of Quercus gambelii Nutt., most of the precipitation occurs during the coldest months of the year. Therefore, we hypothesized that the endophytic fungi of Q. gambelii have the potential to function as psychrotolerant saprotrophs, which we defined in this study as an organism capable of significant growth on leaf litter at 5°C. We further hypothesized that a tradeoff exists between growth of endophytic fungi at 5°C and at 17°C such that fungal isolates are either cold- or warm-temperature specialists. Consistent with our first hypothesis, we found that 36 of our 40 isolates consumed leaf litter at 5°C, but there was a surprisingly high degree of variability among isolates in this ability, even among isolates of a given species. Contrary to our second hypothesis, there was no tradeoff between saprotrophic growth at 5°C and saprotrophic growth at 17°C. Indeed, the isolates that grew poorly as saprotrophs at 5°C were generally those that grew poorly as saprotrophs at 17°C. By virtue of being endophytic, endophytic fungi have priority in litter over decomposer fungi that colonize plant tissues only after they enter the litter pool. Moreover, by virtue of being psychrotolerant, some endophytic fungi may function as saprotrophs during the cold months of the year when moisture is temporarily available. Therefore, we suggest that some endophytic fungi of Q. gambelii could play significant ecosystem roles in litter decomposition and nutrient cycling.


Assuntos
Quercus , Ecossistema , Fungos , Folhas de Planta/microbiologia , Plantas
4.
Arch Microbiol ; 204(11): 675, 2022 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-36264513

RESUMO

Endophytic fungi are microorganisms that colonize the interior of plant tissues (e.g. leaves, seeds, stem, trunk, roots, fruits, flowers) in intracellular and/or extracellular spaces without causing symptoms of disease in host plants. These microorganisms have been isolated from plant species in a wide variety of habitats worldwide, and it is estimated that all terrestrial plants are colonized by one or more species of endophytic fungus. In addition, these microorganisms have been drawing the attention of researchers because of their ability to synthesize a wide range of bioactive molecules with potential for applications in agriculture, medicine and biotechnology. However, several obstacles come up when studying the diversity and chemical potential of endophytic fungi. For example, the usage of an inappropriate surface disinfection method for plant tissue may not eliminate the epiphytic microbiota or may end up interfering with the endophytic mycobiota, which consequently generates erroneous results. Moreover, the composition of the culture medium and the culture conditions can favor the growth of certain species and inhibit others, which generates underestimated results. Other inconsistencies can arise from the fungus misidentification and consequent exploration of its chemical potential. Based on the methodological biases that may occur at all stages of studies dealing with endophytic fungi, the objective of this review is to discuss the main methods employed in these studies as well as highlight the challenges derived from the different approaches. We also report associated tips to help future studies on endophytic fungi as a contribution.


Assuntos
Endófitos , Fungos , Plantas/microbiologia , Raízes de Plantas/microbiologia , Folhas de Planta/microbiologia
5.
Sci Rep ; 12(1): 17880, 2022 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-36284131

RESUMO

Cell death processes in eukaryotes shape normal development and responses to the environment. For plant-microbe interactions, initiation of host cell death plays an important role in determining disease outcomes. Cell death pathways are frequently initiated following detection of pathogen-derived molecules which can lead to resistance or susceptibility to disease depending on pathogen lifestyle. We previously identified several small secreted proteins (SSPs) from the wheat-infecting fungus Zymoseptoria tritici that induce rapid cell death in Nicotiana benthamiana following Agrobacterium-mediated delivery and expression (agroinfiltration). Here we investigated whether the execution of host cells was mechanistically similar in response to different Z. tritici SSPs. Using RNA sequencing, we found that transient expression of four Z. tritici SSPs led to massive transcriptional reprogramming within 48 h of agroinfiltration. We observed that distinct host gene expression profiles were induced dependent on whether cell death occurs in a cell surface immune receptor-dependent or -independent manner. These gene expression profiles involved differential transcriptional networks mediated by WRKY, NAC and MYB transcription factors. In addition, differential expression of genes belonging to different classes of receptor-like proteins and receptor-like kinases was observed. These data suggest that different Z. tritici SSPs trigger differential transcriptional reprogramming in plant cells.


Assuntos
Ascomicetos , Doenças das Plantas , Doenças das Plantas/microbiologia , Células Vegetais , Folhas de Planta/microbiologia , Ascomicetos/genética , Morte Celular , Fatores de Transcrição/metabolismo
6.
FEMS Microbiol Ecol ; 98(10)2022 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-36085374

RESUMO

The phyllosphere harbours a diverse and specific bacterial community, which influences plant health and ecosystem functioning. In this study, we investigated the impact of urban green areas connectivity and size on the composition and diversity of phyllosphere bacterial communities. Hereto, we evaluated the diversity and composition of phyllosphere bacterial communities of 233 Platanus x acerifolia and Acer pseudoplatanus trees in 77 urban green areas throughout 6 European cities. The community composition and diversity significantly differed between cities but only to a limited extent between tree species. We could show that urban intensity correlated significantly with the community composition of phyllosphere bacteria. In particular, a significant correlation was found between the relative abundances for 29 out of the 50 most abundant families and the urban intensity: the abundances of classic phyllosphere families, such as Acetobacteraceae, Planctomycetes, and Beijerinkiaceae, decreased with urban intensity (i.e. more abundant in areas with more green, lower air pollution, and lower temperature), while those related to human activities, such as Enterobacteriaceae and Bacillaceae, increased with urban intensity. The results of this study suggest that phyllosphere bacterial communities in European cities are associated with urban intensity and that effect is mediated by several combined stress factors.


Assuntos
Biodiversidade , Ecossistema , Bactérias/genética , Humanos , Folhas de Planta/microbiologia , Árvores/microbiologia
7.
Arch Microbiol ; 204(10): 600, 2022 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-36056990

RESUMO

Bacteria community provides essential ecological services to rice plants. The bacterial diversity of rice varies across host plant genotype and organs. This study employed 16S rDNA amplicon sequencing to characterise the bacterial community associated with three rice landraces using leaf blade and stem samples. The prokaryotic community found in these rice landraces comprised of two kingdoms, 12 phyla, 25 classes, 40 orders, 80 families, and 118 genera. Proteobacteria (53.9%) was the most abundant phylum. The most abundant genus was an undefined genus under Cyanobacteria (33.0%). Homogeneity of prokaryotic community was observed across the three rice landraces, which may suggest a high similarity in biological and genetical properties of the rice landraces. The difference in prokaryotic composition between leaf blade and stem was depicted based on principal coordinate analysis. This study observed that the prokaryotic inhabitants in rice plants is predominantly determined by rice plant organs.


Assuntos
Cianobactérias , Oryza , Cianobactérias/genética , DNA Ribossômico/genética , Genótipo , Humanos , Oryza/microbiologia , Folhas de Planta/microbiologia , RNA Ribossômico 16S/genética
8.
J Appl Microbiol ; 133(6): 3768-3776, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36106419

RESUMO

AIMS: We compared the bacterial endophytic communities of three genetically different almond cultivars that were all grafted on the same type of rootstock, growing side by side within a commercial orchard. METHODS AND RESULTS: We examined the diversity of leaf bacterial endophytes using cultivation-independent techniques and assessed the relative abundance of bacterial families. Two of these three cultivars were dominated by Pseudomonadaceae, while the bacterial composition of the third cultivar consisted mainly of Streptococcaceae. CONCLUSIONS: The experimental set up allowed us to analyse the impact of the shoot cultivar on endophytes, minimizing the influence of rootstock, biogeography, and cultivation status. Our data suggest that the shoot cultivar can shape the leaf endophytic community composition of almond trees. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results suggest that the shoot cultivar controls the composition of the foliar bacterial endophytic community of almonds. Overall, our results could provide a first step to develop strategies for a more sustainable almond agriculture.


Assuntos
Endófitos , Microbiota , Prunus dulcis , Bactérias/genética , Endófitos/genética , Microbiota/genética , Folhas de Planta/microbiologia , Prunus dulcis/microbiologia
9.
Fungal Biol ; 126(10): 631-639, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36116895

RESUMO

The fungi associated with leaf litter play a key role in decomposition and can be affected both by the warming water and the invasion of non-native species in riparian vegetation. Warming water and invasion of non-native riparian species on stream fungal communities have been studied mainly in temperate ecosystems. We tested the effects of warming water and non-native plant Psidium guajava on leaf litter decomposition, conidia density, species richness and beta diversity of tropical stream fungi. Thus, we carried out an experiment using the current mean temperature of streams from northwestern Paraná in South Brazil (22 °C) and two temperatures above the current mean temperature (26 °C and 29 °C). We also used the leaves of a non-native plant (P. guajava), and two native plants (one of similar nutritional quality, and the other of higher nutritional quality than the non-native species) occurring in Neotropical streams riparian vegetation. Warming water accelerated leaf litter decomposition and reduced conidia density and fungal richness in native and non-native plants. However, species composition and beta diversity were not affected by water temperature. Our study showed that warming affects the fungi of streams, the main microorganisms responsible for decomposition and that the nutritional quality of the leaves may be more important than the origin of riparian plant species. Despite this, further investigations should be conducted on the interaction of P. guajava with the flow of nutrients in these environments and how it can affect other ecosystem processes and the food chain. Efforts to study the effects of water warming and biological invasion on the attributes and distribution of fungi in streams are vital, making them a tool for the conservation of riparian ecosystems.


Assuntos
Ecossistema , Água , Folhas de Planta/microbiologia , Plantas , Rios/microbiologia
10.
Ying Yong Sheng Tai Xue Bao ; 33(7): 1810-1818, 2022 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-36052783

RESUMO

We investigated the decomposition characteristics of Eragrostis minor, mosses, and leaves of Artemisia ordosica with litterbag method in the sand-binding revegetation area, southeastern edge of the Tengger Desert, and further examined their effects on soil microbial communities using the Illumina MiSeq sequencing method. The results showed that the decomposition duration and litter types significantly affected litter decomposition rate. Mosses had the lowest decomposition rate, with a mass loss ratio of only 15.4% after decomposition for 13 months. The average decomposition rates of E. minor and leaves of A. ordosica were 4.9 and 3.4-fold of that of mosses, respectively. During decomposition for 11 months, the dominant bacterial phyla were Actinomycota and Proteobacteria, while that of the fungal community was Ascomycota. Moss decomposition significantly increased the relative abundance of Bacteroidetes and Chloroflexi, but remarkedly decreased the abundance of Basidiomycetes. The diversity and richness of bacterial and fungal communities significantly increased after litter decomposition. The compositional changes of fungal community were significant among litters, but that of bacterial community was not. There was a negative correlation between decomposition rate and the diversity and richness of bacterial and fungal communities. Plant polysaccharides, total phosphorus, soil pH, microbial biomass nitrogen, and soil ammonium content were the main factors affecting microbial community structure. Litter decomposition changed the composition and interspecific similarity within microbial communities, as well as increased the diversity and richness of soil microbial communities, and thus would promote the restoration of soil habitat.


Assuntos
Microbiota , Micobioma , Bactérias , China , Ecossistema , Folhas de Planta/microbiologia , Solo/química , Microbiologia do Solo
11.
FEMS Microbiol Ecol ; 98(10)2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36095133

RESUMO

All living organisms theoretically have an optimal stoichiometric nitrogen: phosphorus (N: P) ratio, below and beyond which their growth is affected, but data remain scarce for microbial decomposers. Here, we evaluated optimal N: P ratios of microbial communities involved in cellulose decomposition and assessed their stability when exposed to copper Cu(II). We hypothesized that (1) cellulose decomposition is maximized for an optimal N: P ratio; (2) copper exposure reduces cellulose decomposition and (3) increases microbial optimal N: P ratio; and (4) N: P ratio and copper modify the structure of microbial decomposer communities. We measured cellulose disc decomposition by a natural inoculum in microcosms exposed to a gradient of N: P ratios at three copper concentrations (0, 1 and 15 µM). Bacteria were most probably the main decomposers. Without copper, cellulose decomposition was maximized at an N: P molar ratio of 4.7. Contrary to expectations, at high copper concentration, the optimal N: P ratio (2.8) and the range of N: P ratios allowing decomposition were significantly reduced and accompanied by a reduction of bacterial diversity. Copper contamination led to the development of tolerant taxa probably less efficient in decomposing cellulose. Our results shed new light on the understanding of multiple stressor effects on microbial decomposition in an increasingly stoichiometrically imbalanced world.


Assuntos
Nitrogênio , Fósforo , Bactérias/genética , Celulose , Cobre/análise , Ecossistema , Nitrogênio/análise , Fósforo/análise , Folhas de Planta/microbiologia , Solo/química , Microbiologia do Solo
12.
Int J Mol Sci ; 23(16)2022 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-36012239

RESUMO

The microbial structure and metabolic function of plant-associated endophytes play a key role in the ecology of various environments, including trees. Here, the structure and functional profiles of the endophytic bacterial community, associated with Paulownia elongata × fortunei, in correlation with seasonality, were evaluated using Biolog EcoPlates. Biolog EcoPlates was used to analyse the functional diversity of the microbiome. The total communities of leaf endophyte communities were investigated using 16S rRNA V5-V7 region amplicon deep sequencing via Illumina MiSeq. Community level physiological profiling (CLPP) analysis by the Biolog EcoPlate™ assay revealed that the carboxylic acids (19.67-36.18%) and amino acids (23.95-35.66%) were preferred by all by all communities, whereas amines and amides (0.38-9.46%) were least used. Seasonal differences in substrate use were also found. Based on the sequencing data, mainly phyla Proteobacteria (18.4-97.1%) and Actinobacteria (2.29-78.7%) were identified. A core microbiome could be found in leaf-associated endophytic communities in trees growing in different locations. This work demonstrates the application of Biolog EcoPlates in studies of the functional diversity of microbial communities in a niche other than soil and shows how it can be applied to the functional analyses of endomicrobiomes. This research can contribute to the popularisation of Biolog EcoPlates for the functional analysis of the endomicrobiome. This study confirms that the analysis of the structure and function of the plant endophytic microbiome plays a key role in the health control and the development of management strategies on bioenergy tree plantations.


Assuntos
Microbiota , Árvores , Bactérias/metabolismo , Endófitos/genética , Microbiota/genética , Folhas de Planta/microbiologia , Plantas/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Microbiologia do Solo , Árvores/genética
13.
Environ Microbiol Rep ; 14(6): 926-933, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35968609

RESUMO

The colonization of six edible plant species: alfalfa, broccoli, coriander, lettuce, parsley and rocket, by the human pathogen Shigatoxigenic Escherichia coli was investigated following two modes of artificial inoculation of seeds, by soaking or watering. The frequency and extent of colonization of cotyledons depended on the mode of inoculation, with three, rapidly germinating species being successfully colonized after overnight soaking, but slower germinating species requiring prolonged exposure to bacteria by watering of the surrounding growth media. Separate analysis of the cotyledons and leaves from individual plants highlighted that successful colonization of the true leaves was also species dependent. For three species, failure of transfer, or lack of nutrients or suitable microhabitat on the leaf surface resulted in infrequent bacterial colonization. Colonization of leaves was lower and generally in proportion to that in cotyledons, if present. The potential risks associated with consumption of leafy produce are discussed.


Assuntos
Escherichia coli O157 , Humanos , Cotilédone , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Folhas de Planta/microbiologia , Plantas , Contaminação de Alimentos/análise
14.
Fungal Biol ; 126(9): 576-586, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36008050

RESUMO

Here, we report the in-situ occurrence of a new fossil-species of Meliolinites (fossil Meliolaceae), Meliolinites bhutanensis sp. nov. on the cuticle fragments of a compressed angiosperm dicot leaf recovered from the middle Siwalik (Formation II: latest Miocene to Pliocene) of Bhutan, eastern Himalaya. This unique foliicolous new fossil fungal species features well-preserved mycelia consisting of superficial, brown to dark brown, septate, thick-walled, branching hyphae with bi-cellular appressoria, unicellular phialides, and a characteristic long, slightly curved hyphal seta. The web-like, brown to dark brown fungal colonies also include globose to sub-globose, dark brown ascomata, and oblong to broadly cylindrical, 5-celled, 4-septate, brown to dark brown, mature ascospores. As almost all features of different stages in the life cycle (ascospores, mature germinating ascospores, superficial lateral hyphae, hyphal seta, hyphopodia, mycelial colony, and ascomata) of this new fossil-species are found, we have proposed the first time a possible life cycle of fossil-species of Meliolaceae. The in-situ evidence of M. bhutanensis on the host leaf cuticle indicates the possible existence of a host-ectoparasite relationship in Bhutan sub-Himalaya's ancient warm and humid tropical evergreen forest during the deposition. So, M. bhutanensis might have thrived generally under warm and humid climate conditions for its growth and development in the Mio-Pliocene time, which is in conformity with our recently published quantitative climatic data by CLAMP (Climate Leaf Analysis Multivariate Program) analysis.


Assuntos
Ascomicetos , Magnoliopsida , Animais , Butão , Fósseis , Estágios do Ciclo de Vida , Folhas de Planta/microbiologia , Esporos Fúngicos
15.
mBio ; 13(5): e0103322, 2022 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-36040028

RESUMO

Hereditary symbioses have the potential to drive transgenerational effects, yet the mechanisms responsible for transmission of heritable plant symbionts are still poorly understood. The leaf symbiosis between Dioscorea sansibarensis and the bacterium Orrella dioscoreae offers an appealing model system to study how heritable bacteria are transmitted to the next generation. Here, we demonstrate that inoculation of apical buds with a bacterial suspension is sufficient to colonize newly formed leaves and propagules, and to ensure transmission to the next plant generation. Flagellar motility is not required for movement inside the plant but is important for the colonization of new hosts. Further, tissue-specific regulation of putative symbiotic functions highlights the presence of two distinct subpopulations of bacteria in the leaf gland and at the shoot meristem. We propose that bacteria in the leaf gland dedicate resources to symbiotic functions, while dividing bacteria in the shoot tip ensure successful colonization of meristematic tissue, glands, and propagules. Compartmentalization of intrahost populations together with tissue-specific regulation may serve as a robust mechanism for the maintenance of mutualism in leaf symbiosis. IMPORTANCE Hereditary symbioses with bacteria are common in the animal kingdom, but relatively unexplored in plants. Several plant species form associations with bacteria in their leaves, which is called leaf symbiosis. These associations are highly specific, but the mechanisms responsible for symbiont transmission are poorly understood. Using the association between the yam species Dioscorea sansibarensis and Orrella dioscoreae as a model leaf symbiosis, we show that bacteria are distributed to specific leaf structures via association with shoot meristems. Flagellar motility is required for initial infection but does not contribute to spread within host tissue. We also provide evidence that bacterial subpopulations at the meristem or in the symbiotic leaf gland differentially express key symbiotic genes. We argue that this separation of functional symbiont populations, coupled with tight control over bacterial infection and transmission, explain the evolutionary robustness of leaf symbiosis. These findings may provide insights into how plants may recruit and maintain beneficial symbionts at the leaf surface.


Assuntos
Alcaligenaceae , Simbiose , Animais , Simbiose/fisiologia , Folhas de Planta/microbiologia , Bactérias , Plantas
16.
J Appl Microbiol ; 133(5): 3228-3238, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35957553

RESUMO

AIMS: In this study, we sought to determine the pathogenic ability of endophytic fungi recovered from the spines of Calamus castaneus, a common rattan palm growing in the forests of Peninsula Malaysia. METHODS AND RESULTS: Ten endophytic fungal isolates were selected for pathogenicity tests: Colletotrichum boninense, Colletotrichum fructicola, Colletotrichum cliviae, Diaporthe hongkongensis, Diaporthe arengae, Diaporthe cf. nobilis, Neopestalotiopsis saprophytica, Neopestalotiopsis formicarum, Fusarium solani and Fusarium oxysporum. These endophytes were tested against leaves of bertam (Eugeissona sp.), oil palm (Elaeis guineensis) and mango (Mangiferae indica) and the fruits of chilli (Capsicum annum), tomato (Solanum lycopersicum) and banana (Musa acuminata). The fungal isolates showed infectivity against bertam, oil palm and mango leaves with degrees of virulence ranging from low to moderate, whereas infectivity against chilli, tomato and banana ranged from low to very high. CONCLUSIONS: Fungal endophytes isolated from the spines of C. castaneus are pathogenic to different crop plants with differing degrees of virulence or aggressiveness. SIGNIFICANCE AND IMPACT OF THE STUDY: Spines of C. castaneus can harbour fungal pathogens of a number of different crops as endophytes. The ability of the fungal endophytes to colonize and infect different crops demonstrate their importance towards agricultural crops. There is a possibility the endophytes behave as latent pathogen. When conditions become favourable, the fungal endophytes transform to pathogenic form and potentially infect other plants.


Assuntos
Calamus , Virulência , Endófitos , Folhas de Planta/microbiologia , Fungos
17.
J Adv Res ; 39: 49-60, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35777916

RESUMO

INTRODUCTION: A broad spectrum of rhizosphere bacteria and fungi were shown to play a central role for health, fitness and productivity of their host plants. However, implications of host metabolism on microbiota assembly in the phyllosphere and potential consequences for holobiont functioning were sparsely addressed. Previous observations indicated that tea plants might reduce disease occurrence in various forests located in their proximity; the underlying mechanisms and potential implications of the phyllosphere microbiota remained elusive. OBJECTIVES: This study aimed atdeciphering microbiome assembly in the tea plant phyllosphere throughout shoot development as well as elucidating potential implications of host metabolites in this process. The main focus was to explore hidden interconnections between the homeostasis of the phyllosphere microbiome and resistance to fungal pathogens. METHODS: Profiling of host metabolites and microbiome analyses based on high-throughput sequencing were integrated to identify drivers of microbiome assembly throughout shoot development in the phyllosphere of tea plants. This was complemented by tracking of beneficial microorganisms in all compartments of the plant. Synthetic assemblages (SynAss), bioassays and field surveys were implemented to verify functioning of the phyllosphere microbiota. RESULTS: Theophylline and epigallocatechin gallate, two prevalent metabolites at the early and late shoot development stage respectively, were identified as the main drivers of microbial community assembly. Flavobacterium and Myriangium were distinct microbial responders at the early stage, while Parabacteroides and Mortierella were more enriched at the late stage. Reconstructed, stage-specific SynAss suppressed various tree phytopathogens by 13.0%-69.3% in vitro and reduced disease incidence by 8.24%-41.3% in vivo. CONCLUSION: The findings indicate that a functional phyllosphere microbiota was assembled along with development-specific metabolites in tea plants, which continuously suppressed prevalent fungal pathogens. The insights gained into the temporally resolved metabolite response of the tea plant microbiota could provide novel solutions for disease management.


Assuntos
Camellia sinensis , Microbiota , Bactérias , Folhas de Planta/microbiologia , Plantas , Chá
18.
Microbiol Res ; 263: 127128, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35868260

RESUMO

The olive crop has expanded in the southeastern region of South America, particularly in Brazil. Thus, the objectives of this study were to identify the diversity of endophytic microorganisms associated with olive leaves with culture-dependent and culture-independent methods, to explore which factors influence the composition and abundance of this microbial community, to identify the trophic mode of these fungi by FunGuild and, to verify type associations between bacterial and fungal communities. Leaf samples were collected from 93 plants in nine locations in the Brazilian states of São Paulo and Minas Gerais. Leaves were first superficially disinfected before fungal isolation and next-generation metabarcoding sequencing was completed targeting the 16S rRNA regions for bacteria and ITS1 for fungi. In total, 800 isolates were obtained, which were grouped into 191 morphotypes and molecularly identified, resulting in 38 genera, 32 of which were recorded for the first time in cultivated olive trees in Brazil. For the isolated fungi, the most abundant trophic level was pathotrophic and for the culture-independent method was unidentified followed by symbiotrophic. The metabarcoding results revealed that factors such as plant age, altitudinal gradient, and geographic location can influence the microbial community of commercial olive plants, while the specific cultivar did not.


Assuntos
Fungos não Classificados , Olea , Bactérias , Brasil , Endófitos , Fungos , Olea/microbiologia , Folhas de Planta/microbiologia , RNA Ribossômico 16S/genética
19.
Sci Rep ; 12(1): 11197, 2022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35778470

RESUMO

Leaf microbiota mediates foliar functional traits, influences plant fitness, and contributes to various ecosystem functions, including nutrient and water cycling. Plant phenology and harsh environmental conditions have been described as the main determinants of leaf microbiota assembly. How climate change may modulate the leaf microbiota is unresolved and thus, we have a limited understanding on how environmental stresses associated with climate change driven weather events affect composition and functions of the microbes inhabiting the phyllosphere. Thus, we conducted a pot experiment to determine the effects of flooding stress on the wheat leaf microbiota. Since plant phenology might be an important factor in the response to hydrological stress, flooding was induced at different plant growth stages (tillering, booting and flowering). Using a metabarcoding approach, we monitored the response of leaf bacteria to flooding, while key soil and plant traits were measured to correlate physiological plant and edaphic factor changes with shifts in the bacterial leaf microbiota assembly. In our study, plant growth stage represented the main driver in leaf microbiota composition, as early and late plants showed distinct bacterial communities. Overall, flooding had a differential effect on leaf microbiota dynamics depending at which developmental stage it was induced, as a more pronounced disruption in community assembly was observed in younger plants.


Assuntos
Microbiota , Triticum , Bactérias/genética , Folhas de Planta/microbiologia , Plantas/microbiologia , Triticum/microbiologia
20.
Proc Natl Acad Sci U S A ; 119(30): e2201285119, 2022 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-35867817

RESUMO

Although complex interactions between hosts and microbial associates are increasingly well documented, we still know little about how and why hosts shape microbial communities in nature. In addition, host genetic effects on microbial communities vary widely depending on the environment, obscuring conclusions about which microbes are impacted and which plant functions are important. We characterized the leaf microbiota of 200 Arabidopsis thaliana genotypes in eight field experiments and detected consistent host effects on specific, broadly distributed microbial species (operational taxonomic unit [OTUs]). Host genetic effects disproportionately influenced central ecological hubs, with heritability of particular OTUs declining with their distance from the nearest hub within the microbial network. These host effects could reflect either OTUs preferentially associating with specific genotypes or differential microbial success within them. Host genetics associated with microbial hubs explained over 10% of the variation in lifetime seed production among host genotypes across sites and years. We successfully cultured one of these microbial hubs and demonstrated its growth-promoting effects on plants in sterile conditions. Finally, genome-wide association mapping identified many putatively causal genes with small effects on the relative abundance of microbial hubs across sites and years, and these genes were enriched for those involved in the synthesis of specialized metabolites, auxins, and the immune system. Using untargeted metabolomics, we corroborate the consistent association between variation in specialized metabolites and microbial hubs across field sites. Together, our results reveal that host genetic variation impacts the microbial communities in consistent ways across environments and that these effects contribute to fitness variation among host genotypes.


Assuntos
Arabidopsis , Interações entre Hospedeiro e Microrganismos , Microbiota , Folhas de Planta , Arabidopsis/genética , Arabidopsis/microbiologia , Estudo de Associação Genômica Ampla , Interações entre Hospedeiro e Microrganismos/genética , Folhas de Planta/genética , Folhas de Planta/microbiologia
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