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The success of in vitro cultivation, particularly for micropropagation purposes, depends on the efficient control of contaminants. In this context, the sterilization of plant material constitutes a fundamental step in initiating cultures. Microbial contaminants can be found either on the surface (epiphyte) or inside plant explants (endophyte). However, the latter is generally challenging to detect and may not always be eradicated through surface sterilization alone. Endophyte contaminants, such as bacteria, can persist within plant material over several cultivation cycles, potentially interfering with or inhibiting in vitro establishment, growth, or recovery of cryopreserved materials. Therefore, microscopy techniques, such as electron microscopy, can yield valuable insights into bacterial endophytes' localization, tissue colonization patterns, and functions in in vitro plant culture. This information is essential for adopting effective strategies for eliminating, preventing, or harmonious coexistence with contaminants.

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AIM: Bacteria that promote plant growth, such as diazotrophs, are valuable tools for achieving a more sustainable production of important non-legume crops like rice. Different strategies have been used to discover new bacteria capable of promoting plant growth. This work evaluated the contribution of soil diazotrophs to the endophytic communities established in the roots of rice seedlings cultivated on seven representative soils from Uruguay. METHODS AND RESULTS: The soils were classified into two groups according to the C and clay content. qPCR, terminal restriction fragment length polymorphism (T-RFLP), and 454-pyrosequencing of the nifH gene were used for analyzing diazotrophs in soil and plantlets' roots grown from seeds of the same genotype for 25 days under controlled conditions. A similar nifH abundance was found among the seven soils, roots, or leaves. The distribution of diazotrophs was more uneven in roots than in soils, with dominance indices significantly higher than in soils (nifH T-RFLP). Dominant soils' diazotrophs were mainly affiliated to Alphaproteobacteria and Planctomycetota. Conversely, Alpha, Beta, Gammaproteobacteria, and Bacillota were predominant in different roots, though undetectable in soils. Almost no nifH sequences were shared between soils and roots. CONCLUSIONS: Root endophytic diazotrophs comprised a broader taxonomic range of microorganisms than diazotrophs found in soils from which the plantlets were grown and showed strong colonization patterns.

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Air pollution caused by tropospheric ozone contributes to the decline of forest ecosystems; for instance, sacred fir, Abies religiosa (Kunth) Schltdl. & Cham. forests in the peri-urban region of Mexico City. Individual trees within these forests exhibit variation in their response to ozone exposure, including the severity of visible symptoms in needles. Using RNA-Seq metatranscriptomic data and ITS2 metabarcoding, we investigated whether symptom variation correlates with the taxonomic and functional composition of fungal mycobiomes from needles collected in this highly polluted area in the surroundings of Mexico City. Our findings indicate that ozone-related symptoms do not significantly correlate with changes in the taxonomic composition of fungal mycobiomes. However, genes coding for 30 putative proteins were differentially expressed in the mycobiome of asymptomatic needles, including eight genes previously associated with resistance to oxidative stress. These results suggest that fungal communities likely play a role in mitigating the oxidative burst caused by tropospheric ozone in sacred fir. Our study illustrates the feasibility of using RNA-Seq data, accessible from global sequence repositories, for the characterization of fungal communities associated with plant tissues, including their gene expression.

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Milpa is an agroecological production system based on the polyculture of plant species, with corn featuring as a central component. Traditionally, the milpa system does not require the application of chemicals, and so pest attacks and poor growth in poor soils can have adverse effects on its production. Therefore, the application of bioinoculants could be a strategy for improving crop growth and health; however, the effect of external inoculant agents on the endemic microbiota associated with corn has not been extensively studied. Here, the objective of this work was to fertilize a maize crop under a milpa agrosystem with the PGPR Pseudomonas fluorescens UM270, evaluating its impact on the diversity of the rhizosphere (rhizobiome) and root endophytic (root endobiome) microbiomes of maize plants. The endobiome of maize roots was evaluated by 16S rRNA and internal transcribed spacer region (ITS) sequencing, and the rhizobiome was assessed by metagenomic sequencing upon inoculation with the strain UM270. The results showed that UM270 inoculation of the rhizosphere of P. fluorescens UM270 did not increase alpha diversity in either the monoculture or milpa, but it did alter the endophytic microbiome of maize plant roots by stimulating the presence of bacterial operational taxonomic units (OTUs) of the genera Burkholderia and Pseudomonas (in a monoculture), whereas, in the milpa system, the PGPR stimulated greater endophytic diversity and the presence of genera such as Burkholderia, Variovorax, and N-fixing rhizobia genera, including Rhizobium, Mesorhizobium, and Bradyrhizobium. No clear association was found between fungal diversity and the presence of strain UM270, but beneficial fungi, such as Rizophagus irregularis and Exophiala pisciphila, were detected in the Milpa system. In addition, network analysis revealed unique interactions with species such as Stenotrophomonas sp., Burkholderia xenovorans, and Sphingobium yanoikuyae, which could potentially play beneficial roles in the plant. Finally, the UM270 strain does not seem to have a strong impact on the microbial diversity of the rhizosphere, but it does have a strong impact on some functions, such as trehalose synthesis, ammonium assimilation, and polyamine metabolism. The inoculation of UM270 biofertilizer in maize plants modifies the rhizo- and endophytic microbiomes with a high potential for stimulating plant growth and health in agroecological crop models.

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Understanding the interactions within and between endophytes and their hosts is still obscure. Investigating endophytic bacterial plant growth-promoting (PGP) traits and co-inoculation effects on legumes' performance is a candidate. Endophytic bacteria were isolated from Vicia sativa root nodules. Such endophytes were screened for their PGP traits, hydrolytic enzymes, and antifungal activities. Sterilized Vicia faba and Pisum sativum seedlings were co-inoculated separately with seven different endophytic bacterial combinations before being planted under sterilized conditions. Later on, several growth-related traits were measured. Eleven endophytes (six rhizobia, two non-rhizobia, and three actinomycetes) could be isolated, and all of them were indole-acetic-acid (IAA) producers, while seven isolates could solubilize phosphorus, whereas three, five, five, and four isolates could produce protease, cellulase, amylase, and chitinase, respectively. Besides, some of these isolates possessed powerful antifungal abilities against six soil-borne pathogenic fungi. Co-inoculation of tested plants with endophytic bacterial mixes (Rhizobiamix+Actinomix+non-Rhizobiamix), (Rhizobiamix+Actinomix), or (Rhizobiamix+non-Rhizobiamix) significantly improved the studied growth parameters (shoot, root fresh and dry weights, length and yield traits) compared to controls, whereas co-inoculated plants with (Rhizobiaalone), (non-Rhizobiamix), or (Actinomix) significantly recorded lower growth parameters. Five efficient endophytes were identified: Rhizobium leguminosarum bv. Viciae, Rhizobium pusense, Brevibacterium frigoritolerans, Streptomyces variabilis, and Streptomyces tendae. Such results suggested that these isolates could be utilized as biocontrols and biofertilizers to improve legumes productivity. Also, co-inoculation with different endophytic mixes is better than single inoculation, a strategy that should be commercially exploited.

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Mountain biodiversity is under unparalleled pressure due to climate change, necessitating in-depth research on high-altitude plant's microbial associations which are crucial for plant survival under stress conditions. Realizing that high-altitude tree line species of Himalaya are completely unexplored with respect to the microbial association, the present study aimed to elucidate plant growth promoting and secondary metabolite producing potential of culturable endophytic fungi of Himalayan silver birch (Betula utilis D. Don). ITS region sequencing revealed that the fungal isolates belong to Penicillium species, Pezicula radicicola, and Paraconiothyrium archidendri. These endophytes were psychrotolerant in nature with the potential to produce extracellular lytic activities. The endophytes showed plant growth promoting (PGP) traits like phosphorus solubilization and production of siderophore, indole acetic acid (IAA), and ACC deaminase. The fungal extracts also exhibited antagonistic potential against bacterial pathogens. Furthermore, the fungal extracts were found to be a potential source of bioactive compounds including the host-specific compound-betulin. Inoculation with fungal suspension improved seed germination and biomass of soybean and maize crops under net house conditions. In vitro PGP traits of the endophytes, supported by net house experiments, indicated that fungal association may support the growth and survival of the host in extreme cold conditions.

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The negative impacts of climate change on native forest ecosystems have created challenging conditions for the sustainability of natural forest regeneration. These challenges arise primarily from abiotic stresses that affect the early stages of forest tree development. While there is extensive evidence on the diversity of juvenile microbial symbioses in agricultural and fruit crops, there is a notable lack of reports on native forest plants. This review aims to summarize the critical studies conducted on the diversity of juvenile plant-microbe interactions in forest plants and to highlight the main benefits of beneficial microorganisms in overcoming environmental stresses such as drought, high and low temperatures, metal(loid) toxicity, nutrient deficiency, and salinity. The reviewed studies have consistently demonstrated the positive effects of juvenile plant-microbiota interactions and have highlighted the potential beneficial attributes to improve plantlet development. In addition, this review discusses the beneficial attributes of managing juvenile plant-microbiota symbiosis in the context of native forest restoration, including its impact on plant responses to phytopathogens, promotion of nutrient uptake, facilitation of seedling adaptation, resource exchange through shared hyphal networks, stimulation of native soil microbial communities, and modulation of gene and protein expression to enhance adaptation to adverse environmental conditions.

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Pigments of fungal origin have aroused increasing interest in the food dye and cosmetic industries since the global demand for natural dyes has grown. Endophytic microorganisms are a source of bioactive compounds, and Amazonian plant species can harbor fungi with a wide range of biotechnological applications. Popularly known in Brazil as crajiru, Fridericia chica is a medicinal plant that produces a red pigment. In this study, a total of 121 fungi were isolated in potato dextrose agar from three plants. We identified nine pigment-producing endophytic fungi isolated from branches and leaves of F. chica. The isolates that showed pigment production in solid media were molecularly identified via multilocus analysis as Aspergillus welwitschiae, A. sydowii, Curvularia sp., Diaporthe cerradensis (two strains), Hypoxylon investiens, Neoscytalidium sp. (two strains) and Penicillium rubens. These isolates were subjected to submerged fermentation in two culture media to obtain metabolic extracts. The extracts obtained were analyzed in terms of their absorbance between 400 and 700 nm. The pigmented extract produced by H. investiens in medium containing yeast extract showed maximum absorbance in the red absorption range (UA700 = 0.550) and significant antioxidant and antimicrobial activity. This isolate can thus be considered a new source of extracellular pigment.

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Actinobacteria that are found in nature have enormous promise for the growth of the pharmaceutical sector. There is a scarce report on the antimicrobial activities of endophytic Actinobacteria from Nigeria. As a result, this study evaluated the Actinobacteria isolated from Nigerian medicinal plants in terms of their biodiversity, phylogenetics, and ability to produce antimicrobial compounds. Following accepted practices, Actinobacteria were isolated from the surface-sterilized plant parts. They were identified using 16S rRNA sequencing, microscopic, and morphological methods. The cell-free broth of Actinobacteria isolates was subjected to antimicrobial assay by agar well diffusion. Molecular evolutionary and genetic analysis (MEGA) version X was used for phylogenetic analysis, and the interactive tree of life (iTOL) version 6.0 was used to view the neighbour-joining method-drawn tree. A total of 13 Actinobacteria were recovered, belonging to three genera including 10 strains of Streptomyces, 2 strains of Saccharomonospora, and only 1 strain of Saccharopolyspora. They showed inhibitory activity against several bacterial pathogens. The phylogenetic tree generated from the sequences showed that our isolates are divergent and distinct from other closely related strains on the database. Further, optimization of the antibiotic production by selected Saccharomonospora sp. PNSac2 was conducted. It showed that the optimal conditions were the ISP2 medium (1-2% w/v salt) adjusted to pH of 8 at 30-32℃ for 12-14 days. In conclusion, endophytic Actinobacteria dwelling in Nigerian soils could be a promising source of new antibiotics. Future research is warranted because more genomic analysis and characterization of their metabolites could lead to the development of new antibacterial medicines.

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Abstract Endophytic fungi are a ubiquituos group that colonize all plant species on earth. Studies comparing the location of endophytic fungi within the leaves and the sampling time in Manihot esculenta Crantz (cassava) are limited. In this study, mature leaves of M. esculenta from Panama were collected in order to compare the cultivable diversity of endophytic fungi and to determine their distribution within the leaves. A total of one hundred sixty endophytes belonging to 97 species representing 13 genera and 8 morphospecies determined as mycelia sterilia that containing 63 isolates were isolated. Cladosporium, Nigrospora, Periconia, and mycelia sterilia 1 and 3 were the most predominant isolated endophytes. We detected that endophytes varied across the sampling time, but not amongst locations within leaves. The endophytes composition across sampling and the location of endophytes within leaf was similar, except for Periconia and mycelia sterilia 3 and 7. The data generated in this study contribute to the knowledge on the biodiversity of endophytic fungi in Panama, and establish the bases for future research focused on understanding the function of endophytes in M. esculenta crops.

Resumo Os fungos endofíticos são um grupo ubiquituo que colonizam todas as espécies de plantas na terra. Os estudos que comparam a localização dos fungos endofíticos dentro das folhas de Manihot esculenta Crantz (mandioca) e o tempo de amostragem são muito escassos. Neste estudo, folhas maduras de M. esculenta foram coletadas do Panamá com a finalidade de comparar a diversidade cultivável de endófitos e determinar sua distribuição dentro das folhas. Um total de 170 endófitos foram isolados de 97 espécies que representam 13 gêneros e 8 morfoespécies determinadas como micélios esterilizados contendo 63 isolados. Os fungos Cladosporium, Nigrospora, Periconia e mycelia sterilia 1 e 3 foram os isolados mais predominantes. Também detectamos que os endófitos variaram ao longo do tempo de amostragem, mas não entre os locais dentro das folhas. A composição de endófitos na amostragem e localização de endófitos dentro da folha foi semelhante, exceto para Periconia e mycelia sterilia 3 e 7. Os dados gerados neste estudo contribuem para o conhecimento da biodiversidade de fungos endofíticos no Panamá e estabelecem as bases para pesquisas sobre o entendimento da função de endófitos em culturas de M. esculenta.

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Abstract Endophytic microorganisms are those that inhabit the interior of plant tissues and organs without causing damage to the plant, triggering a mutualistic interaction. These endophytes are known to produce compounds with various applications in the areas of biotechnology, pharmaceutical industry and agriculture; therefore, molecular methods are used to investigate the phylogeny of these organisms. The Brazilian Cerrado is the second largest biome in Brazil and is considered a hotspot, with a high diversity of endemic fauna and flora. The objective of this work was to analyze, through in silico analysis, the phylogeny of cultivable endophytic fungi isolated from plants found in the Brazilian Cerrado biome. A search was carried out for articles that worked with endophytes in the period between 2012 and 2022. The dendrogram was generated using the Neighbor-joining method based on the ITS1-5.8S-ITS2 conserved region obtained by GenBank codes of isolated endophytes. The genera Xylaria, Diaporthe, and Colletotrichum were isolated in more than three plants in the seven articles found. Most of the articles found related to the biodiversity of endophytic fungi from the Brazilian Cerrado aim at the bioprospecting of bioactive compounds, through culture-dependent methods; as such, a part of endophytic diversity may be lost due to the inability of certain endophytes to grow in artificial media. In silico analysis can assist in the investigation of phylogenetic relationships between endophytic fungi and has the potential to guide future work aimed at prospecting for bioactive compounds, phylogenetic identification, or biodiversity of this group of endophytes.

Resumo Microrganismos endofíticos são aqueles que vivem no interior de tecidos e órgãos vegetais sem causar dano à planta, desencadeando uma interação mutualística. Esses endófitos são conhecidos por produzir compostos com diversas aplicações nas áreas de biotecnologia, indústria farmacêutica e agricultura; logo, métodos moleculares são utilizados para investigar a filogenia destes organismos. O Cerrado brasileiro é o segundo maior bioma do Brasil e é considerado um hotspot, com uma alta diversidade de fauna e flora endêmica. O objetivo deste trabalho foi analisar, por meio da análise in silico, a filogenia de fungos endofíticos cultiváveis isolados de plantas encontradas no bioma Cerrado brasileiro. Foi realizada uma busca por artigos que trabalharam com endófitos no período entre 2012 e 2022. O dendrograma foi gerado usando o método Neighbor-joining baseado na região conservada ITS1-5.8S-ITS2 obtida pelos códigos GenBank de endófitos isolados. Os gêneros Xylaria, Diaporthe e Colletotrichum foram isolados em mais de três plantas nos sete artigos encontrados. A maior parte dos artigos encontrados relacionados à biodiversidade de fungos endofíticos do Cerrado brasileiro visam à bioprospecção de compostos bioativos, através de métodos dependentes de cultura; como tal, uma parte da diversidade endofítica pode ser perdida devido à incapacidade de certos endófitos crescerem em meios artificiais. A análise in silico pode auxiliar na investigação das relações filogenéticas entre fungos endofíticos e tem potencial para orientar trabalhos futuros voltados à prospecção de compostos bioativos, identificação filogenética ou biodiversidade deste grupo de endófitos.

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The extensive distribution of Xylopia aethiopica across the continent of Africa has firmly established its medicinal value in diverse disease management. While its phytochemistry is well established, the diversity, molecular, biochemical, and antimicrobial-biosynthetic characterizations of culturable bacterial endophytes residing in fruits of X. aethiopica have not been studied previously. Additionally, danger continues to loom the global health care and management due to antibiotic resistance; hence, the discovery of microbial natural products especially from endophytes could offer a lasting solution to the quest for novel antimicrobial compounds. In this study, we isolated two bacterial endophytes Serratia sp. XAFb12 and Pseudomonas sp. XAFb13 from fresh X. aethiopica fruit. The 16S rRNA gene sequencing, Vitex biochemical test, Gram staining, and 16S rRNA gene analysis were used to confirm their phenotypic and genotypic profiles. Phylogenetic tree analysis reveals their divergence in a separate branch, indicating their uniqueness. The crude extract of both strains showed inhibition against all tested bacterial and fungal pathogens. The minimum inhibition concentration (MIC) ranged from 2.5 to 10%. Chemical analysis of the crude extracts using gas chromatography-mass spectroscopy (GC-MS) revealed the most abundant compounds to be hydrocinnamic acid, 2-piperidinone, 5-isopropylidene-3,3-dimethyl-dihydrofuran-2-one, and diethyl trisulfide. The bacterial endophytes linked to X. aethiopica were described in this study for the first time in relation to clinically significant pathogens. Our findings imply that crude extracts of the endophytic bacteria from X. aethiopica could be potentially employed as antibiotics. Hence, it is crucial to characterize the active ingredient in further detail for future pharmaceutical applications.

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Endophytic fungi colonize the inter- and/or intracellular regions of healthy plant tissues and have a close symbiotic relationship with their hosts. These microorganisms produce antibiotics, enzymes, and other bioactive compounds that enable them to survive in competitive habitats with other microorganisms. In addition, secondary metabolites confer protection to their host plant against other bacterial and fungal pathogens and/or can promote plant growth. Endophytic fungi are viewed as a promising source of bioactive natural products, which can be optimized through changes in growing conditions. The exploration of novel bioactive molecules produced by these microorganisms has been attracting attention from researchers. The chemical and functional diversity of natural products from endophytic fungi exhibits a broad spectrum of applications in medicine, agriculture, industry and the environment. Fungal endophytes can also enhance the photoprotective effects and photochemical efficiency in the host plants. Modern omic approaches have facilitated research investigating symbiotic plant-endophytic fungi interactions. Therefore, research on endophytic fungi can help discovery novel biomolecules for various biotechnological applications and develop a sustainable agriculture.

Fungos endofíticos colonizam as regiões inter e/ou intracelulares de tecidos vegetais saudáveis e possuem uma relação de simbiose com seus hospedeiros. Esses microrganismos produzem antibióticos, enzimas e outros compostos bioativos que os permitem sobreviver em habitats competitivos com outros microrganismos. Além disso, os metabólitos secundários conferem proteção à planta hospedeira contra outros patógenos bacterianos e fúngicos e/ou podem promover o crescimento vegetal. Os fungos endofíticos são considerados uma fonte promissora de produtos naturais bioativos, que podem ser otimizados por meio de mudanças nas condições de cultivo. A exploração de novas moléculas bioativas produzidas por esses microrganismos tem chamado a atenção dos pesquisadores. A diversidade química e funcional dos produtos naturais de fungos endofíticos exibe um amplo espectro de aplicações na medicina, agricultura, indústria e meio ambiente. Os fungos endofíticos também podem aumentar os efeitos fotoprotetores e a eficiência fotoquímica nas plantas hospedeiras. As abordagens ômicas modernas têm facilitado as pesquisas sobre as interações simbióticas entre plantas e fungos endofíticos. Portanto, a pesquisa sobre fungos endofíticos pode ajudar na descoberta de novas biomoléculas para diversas aplicações biotecnológicas e a desenvolver uma agricultura sustentável.

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Abstract Endophytic fungi are a ubiquituos group that colonize all plant species on earth. Studies comparing the location of endophytic fungi within the leaves and the sampling time in Manihot esculenta Crantz (cassava) are limited. In this study, mature leaves of M. esculenta from Panama were collected in order to compare the cultivable diversity of endophytic fungi and to determine their distribution within the leaves. A total of one hundred sixty endophytes belonging to 97 species representing 13 genera and 8 morphospecies determined as mycelia sterilia that containing 63 isolates were isolated. Cladosporium, Nigrospora, Periconia, and mycelia sterilia 1 and 3 were the most predominant isolated endophytes. We detected that endophytes varied across the sampling time, but not amongst locations within leaves. The endophytes composition across sampling and the location of endophytes within leaf was similar, except for Periconia and mycelia sterilia 3 and 7. The data generated in this study contribute to the knowledge on the biodiversity of endophytic fungi in Panama, and establish the bases for future research focused on understanding the function of endophytes in M. esculenta crops.

Resumo Os fungos endofíticos são um grupo ubiquituo que colonizam todas as espécies de plantas na terra. Os estudos que comparam a localização dos fungos endofíticos dentro das folhas de Manihot esculenta Crantz (mandioca) e o tempo de amostragem são muito escassos. Neste estudo, folhas maduras de M. esculenta foram coletadas do Panamá com a finalidade de comparar a diversidade cultivável de endófitos e determinar sua distribuição dentro das folhas. Um total de 170 endófitos foram isolados de 97 espécies que representam 13 gêneros e 8 morfoespécies determinadas como micélios esterilizados contendo 63 isolados. Os fungos Cladosporium, Nigrospora, Periconia e mycelia sterilia 1 e 3 foram os isolados mais predominantes. Também detectamos que os endófitos variaram ao longo do tempo de amostragem, mas não entre os locais dentro das folhas. A composição de endófitos na amostragem e localização de endófitos dentro da folha foi semelhante, exceto para Periconia e mycelia sterilia 3 e 7. Os dados gerados neste estudo contribuem para o conhecimento da biodiversidade de fungos endofíticos no Panamá e estabelecem as bases para pesquisas sobre o entendimento da função de endófitos em culturas de M. esculenta.

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Several specialised insects can manipulate normal plant development to induce a highly organised structure known as a gall, which represents one of the most complex interactions between insects and plants. Thus far, the mechanism for insect-induced plant galls has remained elusive. To study the induction mechanism of insect galls, we selected the gall induced by Iatrophobia brasiliensis (Diptera: Cecidomyiidae) in cassava (Euphorbiaceae: Manihot esculenta Crantz) as our model. PCR-based molecular markers and deep metagenomic sequencing data were employed to analyse the gall microbiome and to test the hypothesis that gall cells are genetically transformed by insect vectored bacteria. A shotgun sequencing discrimination approach was implemented to selectively discriminate between foreign DNA and the reference host plant genome. Several known candidate insertion sequences were identified, the most significant being DNA sequences found in bacterial genes related to the transcription regulatory factor CadR, cadmium-transporting ATPase encoded by the cadA gene, nitrate transport permease protein (nrtB gene), and arsenical pump ATPase (arsA gene). In addition, a DNA fragment associated with ubiquitin-like gene E2 was identified as a potential accessory genetic element involved in gall induction mechanism. Furthermore, our results suggest that the increased quality and rapid development of gall tissue are mostly driven by microbiome enrichment and the acquisition of critical endophytes. An initial gall-like structure was experimentally obtained in M. esculenta cultured tissues through inoculation assays using a Rhodococcus bacterial strain that originated from the inducing insect, which we related to the gall induction process. We provide evidence that the modification of the endophytic microbiome and the genetic transformation of plant cells in M. esculenta are two essential requirements for insect-induced gall formation. Based on these findings and having observed the same potential DNA marker in galls from other plant species (ubiquitin-like gene E2), we speculate that bacterially mediated genetic transformation of plant cells may represent a more widespread gall induction mechanism found in nature.

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Endophytic bacteria play important roles in medicinal plant growth, abiotic stress, and metabolism. Mirabilis himalaica (Edgew.) Heimerl is known for its medicinal value as Tibetan traditional plant; however, little is known about the endophytic bacteria associated with this plant in different geographic conditions and vegetal tissues. To compare the endophytic bacterial community associated with this plant in different geographic conditions and vegetal tissues, we collected the leaves, stems, and roots of M. himalaica from five locations, Nongmu college (NM), Gongbujiangda (GB), Zhanang County (ZL), Lang County (LX), and Sangri County (SR), and sequenced the 16S rRNA V5-V7 region with the Illumina sequencing method. A total of 522,450 high-quality sequences and 4970 operational taxonomic units (OTUs) were obtained. The different tissues from different locations harbored unique bacterial assemblages. Proteobacteria and Actinobacteria were the dominant phyla in all the samples, while the dominant genera changed based on the different tissues. The endophytic bacterial structures in the leaf and stem tissues were different compared to root tissues. Redundancy analysis (RDA) showed that the endophytic bacterial community was significantly correlated with pH, available phosphorus (AP), total phosphorus (TP), total nitrogen (TN), and soil organic matter (SOM). These findings suggested that the geographic conditions, climate type, ecosystem type, and tissues determined the endophytic bacterial composition and relative abundances. This conclusion could facilitate an understanding of the relationship and ecological function of the endophytic bacteria associated with M. himalaica and provide valuable information for artificial planting of M. himalaica and identifying and applying functional endophytic bacteria.

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This editorial summarizes the main scientific contributions from 11 papers comprising the Special Issue (SI) "Molecular Basis of Crops and Fruit Plants in Response to Stress". Here, we collected papers from different research groups encompassing molecular studies from monocots (ginger, rice, maize) and eudicots (common hazel, cowpea, pepper, soybean, tomato) species submitted to abiotic stresses as heat, cold, salt, drought, and heavy metals or biotic stresses induced by different viruses, such as BPEV, PepGMV, PMMoV, and TEV. These studies explored different aspects of molecular mechanisms involved in plant stress tolerance, establishing comparative analyses among genotypes/cultivars to identify potential molecular markers of stresses that are now available for future application in biotechnological studies. This SI presents a collection of advanced concepts and emerging strategies for readers and researchers aiming to accelerate plant breeding.

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Endophytic fungi are associated with plant health and represent a remarkable source of potential of enzymes and bioactive compounds, but the diversity of endophytes remains uncertain and poorly explored, especially in Cactaceae, one of the most species-rich families adapted to growing in arid and semi-arid regions. The aim of this study was to conduct a systematic review on the diversity and bioprospecting of endophytic fungi from Cactaceae. We analysed peer-reviewed articles from seven databases using PRISMA guidelines. The results showed that the Cactaceae family is a source of new taxa, but the diversity of endophytic fungi of Cactaceae is little explored, mainly the diversity among tissues and by metagenomics. Bioprospecting studies have shown that these microorganisms can be used in the production of enzymes and larvicidal and antifungal compounds. Our results are relevant as a starting point for researchers to develop studies that expand the knowledge of plant mycobiota in arid and semi-arid ecosystems, as well as comprising a remarkable source of fungal compounds with several biotechnological applications.

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Plants associated with mycorrhizal fungi has the ability to establish on metal-contaminated soils playing an important role in phytoremediation programs. The objective of this study was to examine the presence of arbuscular mycorrhizal fungi (AMF) (spores density, diversity, indicator species, and root colonization) and dark septate endophytic fungi (DSE fungal root colonization) in three metal accumulator plants (Sorghum halepense, Bidens pilosa, and Tagetes minuta) growing in soils with high Pb content. The Pb content in AMF spores and plant biomass were also assessed. Rhizosphere soil samples were taken from the three dominant plant species at six study sites surrounding the abandoned Pb smelter and one uncontaminated site. The three studied plants were colonized by AMF and DSE fungi. A total of 24 AMF morphospecies were present in the Pb-contaminated areas. The AMF indicator species in the control site (non-contaminated area) was Funneliformis mosseae and in the most contaminated site were Gigaspora decipiens and Denticustata biornata. There was an increase in mycorrhizal variables such as the number of AMF vesicles, spore number, Pb content in AMF spores and plant biomass and DSE colonization (in Sorghum) with increasing soil Pb contamination, but a decrease in AMF diversity and richness was found. For upcoming soil restoration projects, it is crucial to understand the mycorrhizal fungi as well as the plant community that has adapted to the highly contaminated environment.

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