Genomic characteristics and comparative genomics analyses of non-rhizobial endophytic bacteria isolated from legumes.

In addition to typical nitrogen-fixing endosymbionts, legumes harbour other endophytic bacteria within their tissues that may also contribute to plant growth and health (Hardoim et al. 2015). Our previous works revealed that endophytic bacteria isolated from legumes not only have plant growth-promoting traits but are also well adapted to common constraints present in soils of the Mediterranean region (Brígido et al. 2019ab). In this work, we intend to further characterize these endophytic bacteria through genomic and comparative genomic analyses to potentiate their applications in agriculture, providing opportunities for sustainable plant health and food security. Twelve endophytic bacterial isolates were selected based on their potential for plant growth promotion and/or biocontrol of phytopathogens. Based on the 16S rRNA gene sequence analysis, the isolates were assigned to the genera Pseudomonas, Kosakonia, Stenotrophomonas, Serratia, Bacillus and Agrobacterium. Nevertheless, in silico DNA-DNA hybridization analyses revealed that 3 strains represent novel species distinct from their closest relatives. Their genome sizes ranged from 4.4 M to 7.1 M with a GC content varying from 35.41 to 66.4%. Orthologous gene clusters analysis revealed 9346 clusters and 345 single-copy gene clusters, albeit only 499 gene clusters (comprising 6110 proteins) were shared among all strains. Whole genome sequence analysis revealed genes potentially associated with attachment and plant colonization, growth promotion and stress protection as well as antifungal activity. In detail, sets of genes for twitching motility, chemotaxis, flagella biosynthesis, and ability to form biofilms (which are related with host plant colonization) were found in their genomes. Presence of genes associated to nitrogen fixation, auxin biosynthesis, siderophore production or phosphorous assimilation reveals their potential as plant growth promoters. Furthermore, genes required for biosynthesis of pyoluteorin, 2,4-diacetylphloroglucinol and pyrrolnitrin underline bacterial biocontrol potential against phytopathogens. Genes related to the production of different molecules and enzymes mediating stress tolerance suggest their ability to rapidly adapt to stressful conditions. Overall, our data provide a better understanding of these endophytic bacteria abilities and further comparative genomic analysis provided insight into the genomic basis of their endophytic lifestyle, plant growth promotion and antifungal activity

Evaluating the effect of various bacterial consortia isolated from arid wild legumes on heat stress tolerance of Pisum sativum

High-temperature stress affects the growth and developmental process of cool-season grain legumes. We hypothesized that endophytic bacteria associated with arid plants could be a potential resource to ensure the tolerance of cold-season legumes to high temperature stress events. To test our hypothesis, Phyllobacterium salinitolerans (PH), Starkeya sp. (ST) and Pseudomonas turukhanskensis (PS) endophytes of different spontaneous legumes localised in Tunisian arid regions were selected to evaluate their potential in improving Pisum sativum growth and pea-rhizobia symbiosis under a heat stress event. Three consortia (containing different combinations of endophytes) were used along with the pea microsymbiont Rhizobium leguminosarum 128C53 (WT) or with its ΔacdS mutant derivative (MT) (Ma et al., 2003). Uninoculated plants without or with nitrogen supplement were used as negative (NC) or positive controls (PC), respectively. The heat stress event was applied 2 weeks after sowing for a period of 2 weeks with consecutive cycles of 30-35°C/16h and 20°C/8h. Interestingly, the shoot dry weight (SDW) of all plants co-inoculated with WT and any of the consortia containing PH increased significantly compared to that of plants inoculated with WT alone. A similar effect was observed on the root dry weight (RDW) in the treatments WT+ST+PH and WT+PS+PH. On the other hand, the best results either in terms of SDW or RDW with the mutant strain was the treatment that included all endophytes (MT+ST+PS+PH), even overcoming all treatments inoculated with WT and equalling the PC. As expected, plants inoculated with the MT had a lower number of nodules (NN) compared to plants inoculated with WT, except for MT+ST+PS+PH with similar NN. A significant increase in the NN was observed in plants co-inoculated with WT+ST+PH and WT+PS+PH compared to those in WT. The highest total chlorophyll content was in WT+ST+PS, which was significantly different from all other treatments while no differences were observed in phenolic compounds content among the inoculated treatments. Overall, our results suggest that endophytic isolates from arid leguminous plants are good candidates for increasing the resilience of plants not adapted to heat stress

Endophytic bacteria associated with spontaneous legumes in arid zones of Tunisia: Genetic diversity, metabolic functionalities and potential application to mitigate the impact of climate change

Legumes naturally adapted to harsh climate environments represent a new source of plant growth promoting (PGP) bacteria that can be used to improve crop resilience to climate change. However, the diversity and functionality of endophytic bacteria associated with endemic wild legumes in Tunisia are almost unknown. To study the taxonomic and functional diversity of these species, we conducted a study on root nodules of 15 spontaneous legumes, some of which studied for the first time, growing in three different Tunisian bioclimates (arid, semi-arid and Saharan). More than 210 strains, corresponding to 78 different phylotypes, were isolated. Sequencing of the 16S rDNA revealed the presence of rhizobial isolates belonging to the genera: Rhizobium, Sinorhizobium, Bradyrhizobium, Mesorhizobium, Neorhizobium, Agrobacterium, Phyllobacterium, Cupriavidus and Burkholderia. Other non-rhizobial bacteria assigned to Microbacterium, Pseudomonas, Paenibacillus, Starkeya, Kocuria among others, were also obtained. In addition, the nucleotide similarity of housekeeping genes suggested the presence of new species in our collection. Indeed, the genomic sequencing analysis identified a new species of Mesorhizobium (PRJNA800673), a microsymbiont of Retama raetam, which is one of the most important Tunisian shrubs. Regarding PGP-screening abilities, several strains stood out for possessing several PGP traits, phosphate solubilization, indole acetic acid and siderophores production, along with high tolerance to abiotic stress (> 45°C; > 0.4M NaCl). For rhizobia, whole genome sequencing of the Saharan isolate Sinorhizobium meliloti IRAM:0087 (PRJNA842649) revealed the existence of several gene clusters coding for different PGP activities, rhizosphere competitiveness and stress tolerance, some of which were confirmed in vitro assays. Based on the evaluation of the PGP potential of non-rhizobial strains, three bacteria P. salinitolerans, P. turukhanskensis and Starkeya sp. were selected to improve Pisum sativum, a cold season crop, tolerance to a heat stress event. Our preliminary results suggest that endophytic isolates from arid legumes represent a promising resource of biofertilizers/biostimulants to increase plant resilience to heat stress. Future studies to explore the adaptative responses of these endophytes to different types of stress will allow to better understand their stress tolerance mechanisms and contribute to select strains for nature-based solutions towards the establishment of new agricultural technologies in drylands

Role of QseG membrane protein in beneficial enterobacterial interactions with plants and Mesorhizobia

Membrane protein Quorum sensing G (QseG) positively interferes in the process of colonization and infection of enteric pathogens in animals. Its gene is located between qseE and qseF genes and is co-transcribed with the two-component system. Homologs of qseG gene, along with qseEF, are present in many Enterobacteriaceae; however, its role in nonpathogenic strains is still unknown. To fill this knowledge gap, we investigated the role of QseG protein of a plant-associated enterobacterium in the interactions with its legume host and in the benefits induced by this enterobacterium in the Mesorhizobium-chickpea symbiosis. Here, we show that Kosakonia sp. MH5 ΔqseG mutant was defective in internal root colonization and inoculation of chickpea seedlings with this mutant increased the expression of the defence-related gene CaRBOH-like in host roots. Furthermore, we show that invasion and a proper establishment within the roots and/or root nodules are essential for MH5 strain to be able to exert beneficial effects on the symbiotic Mesorhizobium-chickpea association under salinity. This study demonstrates, for the first time, that the role of QseG is transversal to pathogenic and nonpathogenic enterobacteria and is a step forward to better understanding the molecular bases of plant-bacteria interactions established between legume and beneficial endophytic enterobacteria

Role of QseG membrane protein in beneficial enterobacterial interactions with plants and Mesorhizobia

Homologs of qseG gene (coding for the membrane protein QseG), along with the qseEF genes, are present in many Enterobacteriaceae; however, its role in non-pathogenic strains is still unknown. To fill this knowledge gap, we investigated the role of QseG protein of a plant-associated enterobacterium in the interactions with its legume host and in the benefits induced by this enterobacterium in the Mesorhizobium–chickpea symbiosis. Here, we showed that QseG of Kosakonia sp. MH5 is involved in the following processes: (i) the evasion of the plant immune system and (ii) the efficient colonization of chickpea root cells. Furthermore, these features are essential for the beneficial effects of this strain on the Mesorhizobium–chickpea symbiosis. This study demonstrates that the role of QseG is transversal to pathogenic and non-pathogenic enterobacteria and is a step forward to better understanding the molecular bases of plant–bacteria interactions established between legume and beneficial endophytic enterobacteria.ME

Splicing Factors in Breast Cancer: Drivers of the Breast Tumor Fate

Splicing is a critical step in gene expression, responsible for the excision of introns, producing the mature form of mRNA. Also, the possible arrangements of exons enlarge the proteome in 80%, enabling one gene to encode more than one protein isoform, thus increasing proteome. Growing data show deregulation of splicing events in cancer, being breast cancer the most studied. This aberrant pattern of splicing has an important role in breast tumor progression. These alterations are mainly caused by misexpression of some critical alternative splicing factors. The behavior of these splicing factors is implicated with important clinical features, such as chemoresistance, aggressiveness, and also metastases. In this chapter, the role of five splicing factors is discussed in the light of relevant data about in vitro, in vivo, and ex vivo studies to construct a representative scheme of their behavior in breast cancer progression. Although the presented five splicing factors have important role in breast cancer, only three of them (ESRP1, RBFOX2, and SRSF1) have a more prominent role in tumorigenesis and tumor progression. These concepts will elucidate their role in tumorigenesis and a prospective use as biomarkers in breast cancer

Adorno:: uma crítica aos advogados da indústria cultural

A proposta que norteia esta pesquisa encontra seu fundamento na crítica de Theodor Adorno aos advogados da “Indústria Cultural”. Procuramos investigar em que consiste tal crítica, dando evidência às suas principais características, bem como aos seus reflexos no corpo social, uma vez que, a arte e a cultura, que são manifestações do espírito humano, tornaram-se produtos industrializados e comercializados, perdendo a sua essência. O escopo da arte e da cultura, entendida como a libertação e a emancipação do homem, fora violado, sendo transformado em meras mercadorias descartáveis, com a finalidade de disseminar o pensamento da classe dominante através do seu sistema econômico, acarretando em uma pseudo-individualidade. O homem passou a ser objeto de manipulação da indústria que transforma tudo em mercadoria. Esta maquinaria engloba tudo, e nem mesmo alguns atos de contestação deixam de ser incorporados e diluídos pela Indústria Cultural que rapidamente procura transformá-las em produtos para comercialização, revelando que tudo aquilo que está contra o sistema é absorvido e reinterpretado, tragando a individualidade. Os homens, por sua vez, se não aderirem à forma de pensar imposta pela Indústria, soçobrarão em meio à multidão consumidora. Assim, nossa análise compreende esta Indústria como um braço do sistema capitalista, que através dos meios de comunicação de amplo acesso, exerce grande influência na difusão e disseminação da ideologia desse sistema

Introduction of exogenous AMF species alters the biological diversity and functionality of AMF communities associated with cowpea

The salinity in arid and semi-arid areas of the world is rapidly expanding due to climate change and anthropogenic activities. The use of inoculants containing beneficial microbes (e.g. arbuscular mycorrhizal fungi (AMF) and rhizobia) is a promising alternative to improve plant production in these regions. Here, we investigated the effect of common agricultural practices such as the use of beneficial microbes as inoculum and crop rotation on cowpea growth and on its association with soil microbes under non- and salt-stressed conditions. Plant experiments were carried out using non-sterilized soil (supplemented or not with NaCl) under greenhouse conditions. Bradyrhizobium yuanmingense BR 3267 strain and a commercial mixture of AMF (Endoplant Riego) were used as inoculants. In parallel, we assessed cowpea growth following succession of buffelgrass (Cenchrus ciliaris) with or without prior soil disturbance. Plant and symbiotic parameters, nutrient content in leaves and AMF and root nodule communities through DNA metabarcoding were evaluated. Under non-stressed conditions, inoculation with AMF and/or BR 3267 strain led to significant increase of cowpea biomass production and higher N or P content in leaves. The imposed saline condition affected the cowpea growth although without significantly affecting the symbiotic parameters. Moreover, the increase of AMF propagules available in the soil at buffelgrass sowing through the inoculation of commercial AMF was a determining factor to mitigate the effects of soil tillage and salinity on cowpea growth. The bacterial communities in the root nodules were affected by AMF communities rather by rhizobia inoculation. Benefits of commercial AMF could be explained by changes in the biological and functionality of the AMF communities associated with cowpea. This study reveals that microbial inoculation and crop rotation are effective practices for improvement of cowpea growth and on mitigating the harmful effects of salt

Dupla inoculação (rizóbio e fungos micorrízicos arbusculares) mitigam efeitos nocivos da salinidade no crescimento do feijão-caupi

A salinidade em áreas áridas e semiáridas do mundo está a expandir rapidamente devido às alterações climáticas e atividades humanas. O uso de inóculos contendo microrganismos benéficos, como fungos micorrízicos arbusculares (FMA) e bactérias simbióticas fixadoras de azoto, aliado ao manejo adequado do solo e das culturas, é uma alternativa promissora para melhorar a produção vegetal nessas regiões. Aqui, investigámos o efeito de práticas agrícolas comuns, nomeadamente a utilização de microrganismos benéficos como inóculo e a perturbação do solo entre a rotação de culturas, no crescimento do feijão-caupi e na sua associação com micróbios do solo sob condições salinas e não salinas. A estirpe Bradyrhizobium yuanmingense BR 3267, e uma mistura comercial de FMA (Endoplant Riego) foram utilizados como inóculos. Paralelamente, avaliámos o crescimento do feijão-caupi, após sucessão ao capim-buffel com ou sem perturbação prévia do solo. Ensaios de plantas em solo não-esterilizado (suplementado ou não com NaCl) foram realizados em dois ciclos de 75 dias em estufa. Parâmetros vegetais e simbióticos e o teor de nutrientes nas folhas foram determinados, bem como a diversidade bacteriana e de FMA em raízes e nódulos de feijão-caupi por meio de sequenciamento DNA metabarcode. Os nossos dados revelaram que os parâmetros simbióticos (número de nódulos e/ou taxa de colonização) foram melhorados no feijão-caupi inoculado com Bradyrhizobium e/ou FMA comercial, o que consequentemente resultou em maior teor de N ou P nas folhas. A salinidade imposta afetou negativamente o crescimento do feijão, porém sem afetar significativamente os parâmetros simbióticos analisados. O aumento de propágulos de FMA disponíveis no solo através da inoculação de FMA comercial foi um fator determinante para mitigar os efeitos do manejo do solo no crescimento do feijão. A perturbação do solo mostrou impacto negativo nos parâmetros vegetais e simbióticos, exceto para o número de nódulos. Além disso, os efeitos positivos do uso de FMA comercial no crescimento do feijão-caupi, em condições controlo ou de salinidade podem ser explicados pelas mudanças na funcionalidade das comunidades de FMA associadas ao feijão-caupi. Por outro lado, as comunidades bacterianas em nódulos ou raízes do feijão não foram afetadas pela inoculação de FMA ou de rizóbios. Este estudo revela que a dupla inoculação (mistura de rizóbio e FMA) e a rotação de culturas, sem a perturbação do solo, são práticas eficazes para melhorar o crescimento do feijão-caupi e mitigar os efeitos nocivos do sal no seu crescimento. Mais, estes resultados também sugerem que os efeitos sinérgicos entre rizóbios e FMA dependem principalmente de um estabelecimento bem-sucedido da simbiose entre FMA e a planta hospedeira e não da comunidade de FMA em si