Endophytic fungal community structure in olive orchards with high and low incidence of olive anthracnose

Fungal endophytes have been increasingly recognized to promote host plant protection to pathogens, but knowledge of the multiple effects that they could have in crop diseases is still scarce. This work attempts to understand the role of fungal endophytes in crop diseases, specifically in reducing disease development and interfering on lifestyle transition of the pathogen. To accomplish this, the endophytic fungal community of reproductive organs of olive tree from two orchards showing different levels of anthracnose incidence, a major disease of olive fruits, was characterized and compared between them. The two orchards showed distinct endophytic communities, differing in species richness, abundance and composition, with highest isolation rates and richness of endophytes in the orchard with low anthracnose incidence. These differences among orchards were greater on fruits than on flowers, suggesting that these changes in endophytic fungal composition may influence the lifestyle shifts in pathogen (from latent to pathogen). A number of fungal taxa were found to be positively associated to one of the two orchards. The fungal endophytes best correlated with high incidence of anthracnose are pathogens, while endophytes-associated to low anthracnose incidence are described to protect plants. Altogether, the results suggest varying pathogen-endophyte interactions among the two orchards.This work is supported by FEDER funds through the COMPETE (Operational Programme for Competitiveness Factors) and by the Foundation for Science and Technology (FCT, Portugal) within the POCI-01-0145- FEDER-031133 Project (MicOlives—Exploiting plant induced resistance by beneficial fungi as a new sustainable approach to olive crop protection), and FCT/MCTES to CIMO (UIDB/00690/2020). F. Martins thanks the award of a PhD scholarship (ref. SFRH/BD/112234/2015) by FCT.info:eu-repo/semantics/publishedVersio

Evaluation of the biocontrol potential of an antagonist against olive knot disease in olive trees (Olea europaea L.)

The olive knot, caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv), is one of the most serious diseases affecting olive tree (Olea europaea L.) in many regions of the world and mainly in Mediterranean countries. This disease produces tumors, especially in olive tree stems and trunk, leading to the death of the plant. In recent years, the use of microbial biocontrol agents for the control of plant diseases has gained considerable attention. Previous studies have revealed that, several bacteria strains naturally occurring in the olive tree phyllosphere, exhibit capacity to inhibit in vitro growth of Psv, being the greatest antagonistic effect displayed by Bacillus En40. The aim of the present study was to evaluate the ability of this strain to suppress Psv and olive knot development in olive trees. Pot experiments were conducted with 2-year-old olive plantlets cv. Cobrançosa inoculated with the selected strain or Psv, or in combination of both. Phenotypic traits associated with plant growth (e.g. biomass yield, total shoot/root height, and photosynthetic pigments content) and biocontrol abilities (e.g. abundance of Psv and assessment of disease symptoms) were evaluated, up to 120 days after inoculation. While development and growth of Psv+antagonist-inoculated plants showed to be similar to non-inoculated plants, photosynthetic pigments contents were observed to be higher in antagonist-inoculated plants than in other treatments. When compared with Psv-inoculated plants, plants treated with the antagonist revealed a significant reduction (p<0.01) in knots formation and size. Antagonist-inoculated plants showed also a reduction of the abundance of Psv in the inoculation sites (from 22.4 to 7.5 UFC/μL, p<0.01), suggesting its capacity to reduce the patogen's growth. This strain was identified to supres Psv and disease development on olive plants and thus, it should be considered in the future as a possible biocontrol agent against olive knot disease.This work is funded by FEDER funds through COMPETE (Programa Operacional Factores de Competitividade) and by national funds by FCT (Fundação para a Ciência e a Tecnologia) in the framework of the project EXCL/AGR-PRO/0591/2012. D. MINA thanks thinfo:eu-repo/semantics/publishedVersio

Impact of plant genotype and plant habitat in shaping bacterial pathobiome: a comparative study in olive tree

Plant-inhabiting microorganisms interact directly with each other affecting disease progression. However, the role of host plant and plant habitat in shaping pathobiome composition and their implication for host susceptibility/resistance to a particular disease are currently unknown. For the elucidation of these questions, both epiphytic and endophytic bacterial communities, present in asymptomatic and symptomatic twigs from olive cultivars displaying different susceptibilities to olive knot (OK) disease, were investigated using culturing methods. OK disease was the main driver of the bacterial community, causing changes on their diversity, abundance and composition. OK disease effect was most notorious on OK-susceptible cultivar and when considering the endophytic communities. Plant habitat (epiphytes vs. endophytes) also contributed to the bacterial community assembling, in particular on symptomatic twigs (knots) of OK-susceptible cultivar. In contrast, host cultivar had little effect on the bacterial community composition, but OK-symptomatic twigs (knots) revealed to be more affected by this driver. Overall, the pathobiome seems to result from an intricate interaction between the pathogen, the resident bacteria, and the plant host. Specific bacterial genera were associated to the presence or absence of OK disease in each cultivar. Their ability to trigger and/or suppress disease should be studied in the future.The authors are grateful to the FEDER and Foundation for Science and Technology (FCT, Portugal) under Programme PT2020 for financial support to CIMO (UIDB/00690/2020) and BioISI (UID/MULTI/04046/2013), as well as the Horizon 2020, the European Union's Framework Programme for Research and Innovation, for financial support the project PRIMA/0002/2018 INTOMED -Innovative tools to combat crop pests in the Mediterranean. D. Mina thanks FCT, POPH-QREN and FSE for SFRH-BD-105341/2014 grant

Epiphytic and endophytic bacteria on olive tree phyllosphere: Exploring tissue and cultivar effect

Variation on bacterial communities living in the phyllosphere as epiphytes and endophytes has been attributed to plant host effects. However, there is contradictory or inconclusive evidence regarding the effect of plant genetics (below the species' level) and of plant tissue type on phyllosphere bacterial community assembly, in particular when epiphytes and endophytes are considered simultaneously. Here, both surface and internal bacterial communities of two olive (Olea europaea) cultivars were evaluated in twigs and leaves by molecular identification of cultivable isolates, with an attempt to answer these questions. Overall,Proteobacteria,ActinobacteriaandFirmicuteswere the dominant phyla, being epiphytes more diverse and abundant than endophytes. Host genotype (at cultivar level) had a structuring effect on the composition of bacterial communities and, in a similar way, for both epiphytes and endophytes. Plant organ (leaf vs. twig) control of the bacterial communities was less evident when compared with plant genotype and with a greater influence on epiphytic than on endophytic community structure. Each olive genotype/plant organ was apparently selective towards specific bacterial operational taxonomic units (OTUs), which may lead to specific feedbacks on fitness of plant genotypes. Bacterial recruitment was observed to happen mainly within epiphytes than in endophytes and in leaves as compared with twigs. Such host specificity suggested that the benefits derived from the plant-bacteria interaction should be considered at genetic levels below the species.The authors are grateful to the FEDER and Foundation for Science and Technology (FCT, Portugal) under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2019) and BioISI (UID/MULTI/04046/2013), as well as the Horizon 2020, the European Union’s Framework Programme for Research and Innovation, for financial support the project PRIMA/0002/2018 INTOMED—Innovative tools to combat crop pests in the Mediterranean. D. Mina thanks FCT, POPH-QREN and FSE for SFRH-BD-105341/2014 grant

Biological control of Pseudomonas savastanoi pv. savastanoi by two bacterial isolated from olive tree phyllosphere

Olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv), has been responsible for high economical crop losses in olive orchards, especially in Mediterranean countries. Olive knot cannot be eradicated once it is established in an orchard, and therefore its control is based on preventive measures. Laboratory experiments previously performed by us have showed the capacity of some bacterial species, isolated from olive tree phyllosphere, to inhibited Psv growth. In the present work, the two most promising bacterial isolates (i.e. Frondihabitans sp. and Paenibacillus sp.) were evaluated for the control of Psv in olive plantlets (Olea europaea L.) under greenhouse conditions, to predict their effect in a more natural condition. In pot experiments, two-year-old olive plants cv. Cobrançosa were inoculated with the antagonistic bacteria and Psv individually or in combination. Inoculations were performed in wounds previously made in three different sites of the main stem. Thirty replicate plants were used per strain. The plants were observed for symptom development and the number of bacteria on the inoculation sites was periodically evaluated, for up to 120 days after inoculation. To quantify the reduction of symptom expression, knots were excised from stems and their weights were compared between treatments. Inoculation with Psv resulted in the formation of knots with significantly higher weight values compared to plants inoculated simultaneously with Psv and antagonistic bacteria. Both tested bacterial also showed the capacity to reduce the amount of Psv in the inoculation sites, suggesting their effectiveness in controlling the multiplication of the pathogen. Data presented here demonstrate for the first time the potential of these bacteria for suppression of olive knot, and these two species should be considered in the future as potential biocontrol agents against Psv.This work is funded by FEDER funds through COMPETE (Programa Operacional Factores de Competitividade) and by national funds by FCT (Fundação para a Ciência e a Tecnologia) in the framework of the project EXCL/AGR-PRO/0591/2012. D. MINA thanks the Fundação para a Ciência e Tecnologia (FCT), Portugal for the Ph.D. grant SFRH/BD/105341/2014info:eu-repo/semantics/publishedVersio

Biological control of Pseudomonas savastanoi pv. savastanoi by two bacterial isolated from olive tree phyllosphere

Olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv), has been responsible for high economical crop losses in olive orchards, especially in Mediterranean countries. Olive knot cannot be eradicated once it is established in an orchard, and therefore its control is based on preventive measures. Laboratory experiments previously performed by us have showed the capacity of some bacterial species, isolated from olive tree phyllosphere, to inhibited Psv growth. In the present work, the two most promising bacterial isolates (i.e. Frondihabitans sp. and Paenibacillus sp.) were evaluated for the control of Psv in olive plantlets (Olea europaea L.) under greenhouse conditions, to predict their effect in a more natural condition. In pot experiments, two-year-old olive plants cv. Cobrançosa were inoculated with the antagonistic bacteria and Psv individually or in combination. Inoculations were performed in wounds previously made in three different sites of the main stem. Thirty replicate plants were used per strain. The plants were observed for symptom development and the number of bacteria on the inoculation sites was periodically evaluated, for up to 120 days after inoculation. To quantify the reduction of symptom expression, knots were excised from stems and their weights were compared between treatments. Inoculation with Psv resulted in the formation of knots with significantly higher weight values compared to plants inoculated simultaneously with Psv and antagonistic bacteria. Both tested bacterial also showed the capacity to reduce the amount of Psv in the inoculation sites, suggesting their effectiveness in controlling the multiplication of the pathogen. Data presented here demonstrate for the first time the potential of these bacteria for suppression of olive knot, and these two species should be considered in the future as potential biocontrol agents against Psv.info:eu-repo/semantics/publishedVersio

Endophytic fungal community succession in reproductive organs of two olive tree cultivars with contrasting anthracnose susceptibilities

The factors shaping endophytic fungal assemblages in reproductive organs have been less evaluated than in vegetative organs. Here, the temporal dynamics of fungal endophytes in inflorescences and fruits of olive tree cultivars with contrasting anthracnose susceptibilities was assessed, starting before flowers open until fruit ripening. Fungal diversity assessed by rRNA sequencing of cultivable isolates revealed a higher richness and abundance of endophytes in inflorescences than in fruits. Endophytes from Sordariomycetes were dominant in inflorescences, while in fruits they were from Dothideomycetes. The overall assemblages of inflorescences and fruits were shaped mainly by the plant organ, followed by the phenological stage and lastly, by the plant cultivar. The importance of cultivar as a shaping factor varied according to the plant organ, being only significant in inflorescence-associated endophytes. A set of fungal taxa were positively associated with a particular cultivar and phenological stage, likely contributing to the plant anthracnose resistance.This work is supported by FEDER funds through the COMPETE (Operational Programme for Competitiveness Factors) and by the Foundation for Science and Technology (FCT, Portugal) within the POCI-01-0145-FEDER-031133 (MicOlives) project and FCT/MCTES to CIMO (UIDB/00690/2020). F. Martins thanks the award of a PhD scholarship (ref. SFRH/BD/112234/2015) by FCT.info:eu-repo/semantics/publishedVersio

“A verdade vos libertará”: a desinformação e a pós-verdade no Governo Bolsonaro no combate à Covid-19

Biblical verses are widely used by government officers in Jair Messias Bolsonaro Administration, president of Brazil since 2019. However, the practice has not been the same as the theory, since, in their official and unofficial speeches, fake news that promote misinformation. This paper aims to present evidence that the Government contributed to disinformation in the fight against Covid-19 in Brazil. The qualitative-quantitative, exploratory and descriptive research was developed by collecting the publications of the President of the Republic of Brazil on Twitter. It was counted the times that he mentioned, in the posts on his Twitter account, the use of medicines and substances with no proven effectiveness in combating the pandemic of the new coronavirus. His speech was analyzed from the notions of "information" of fundamental authors of Information Science and of truth and "post-truth", with the purpose of explaining the reasons why disinformation finds echoes in the followers of that president, leading to the context of their speeches and behaviors in other communication vehicles is taken into account. The results demonstrate how disinformation, even in a private account disguised as public/official, on social media, has major repercussions in the lack of adequate measures and treatment and, consequently, in the deaths caused by Covid-19 in the country. It is concluded that some of their posts and attitudes culminated in hate speeches and attacks by their followers on opponents of the Government, putting society in a limbo of misinformation, lost as to which health recommendation to follow and who to believe. After all, the word of the authority that should release (from the pandemic) did not align with scientific research and the recommendations of the World Health Organization, echoing contradictions, untruths and misinformation.Los versículos bíblicos son muy utilizados por los actores del Gobierno de Jair Messias Bolsonaro, presidente de Brasil desde 2019. Sin embargo, la práctica no ha sido igual a la teoría, ya que en sus discursos oficiales y extraoficiales aparecen fake news que promueven la desinformación. Este trabajo tiene como objetivo presentar evidencias de que el Gobierno contribuyó a la desinformación en la lucha contra el Covid-19 en el Brasil. La investigación cualitativa-cuantitativa, exploratoria y descriptiva se desarrolló a partir de la recopilación de las publicaciones del Presidente de la República de Brasil en Twitter. Se contaron las veces que mencionó, en las publicaciones de su cuenta de Twitter, el uso de medicamentos y sustancias sin eficacia comprobada para combatir la pandemia del nuevo coronavirus. Su discurso fue analizado desde las nociones de "información" de autores fundamentales de las Ciencias de la Información y de verdad y "posverdad", con el propósito de explicar las razones por las cuales la desinformación encuentra ecos en los seguidores de ese presidente, llevándolos al contexto de se tienen en cuenta sus discursos y comportamientos en otros vehículos de comunicación. Los resultados demuestran cómo la desinformación, incluso en una cuenta privada disfrazada de pública/oficial, en las redes sociales, tiene importantes repercusiones en la falta de medidas y tratamientos adecuados y, consecuentemente, en las muertes provocadas por la Covid-19 en el país. Se concluye que algunas de sus publicaciones y actitudes culminaron en discursos de odio y ataques de sus seguidores a opositores al Gobierno, poniendo a la sociedad en un limbo de desinformación, sin saber qué recomendación sanitaria seguir y a quién creer. Después de todo, la palabra de la autoridad que debería liberar (de la pandemia) no se alineó con la investigación científica y las recomendaciones de la Organización Mundial de la Salud, haciéndose eco de contradicciones, falsedades y desinformación.Versículos bíblicos são muito utilizados por atores do Governo Jair Messias Bolsonaro, presidente do Brasil desde 2019. Porém, a prática não tem sido a mesma que a teoria, uma vez que, nos seus discursos oficiais e extraoficiais, são veiculadas fake news que promovem a desinformação. Este trabalho objetiva apresentar evidências de que o Governo contribuiu com a desinformação no combate à COVID-19 no país. A pesquisa quali-quantitativa, exploratória e descritiva desenvolveu-se mediante a coleta das publicações do Presidente da República do Brasil no Twitter. Contabilizou-se as vezes que ele mencionou, nas postagens em sua conta no Twitter, o uso de remédios e substâncias sem eficácia comprovada no combate à pandemia do novo coronavírus. O seu discurso foi analisado a partir das noções de “informação” de autores fundamentais da Ciência da Informação e de verdade e “pós-verdade”, com o propósito de explicar as razões pelas quais a desinformação encontra ecos nos seguidores do referido presidente, levando-se em conta o contexto de suas falas e comportamentos em outros veículos de comunicação. Os resultados demonstram como a desinformação, mesmo em uma conta privada disfarçada de pública/oficial, em uma mídia social, tem grandes repercussões na falta de medidas e tratamento adequado e, por consequência, nas mortes ocasionadas pelo Covid-19 no país. Conclui-se que algumas de suas postagens e atitudes culminaram em discursos de ódio e ataques de seus seguidores aos opositores do Governo, colocando a sociedade em um limbo de desinformação, perdida quanto à qual recomendação sanitária seguir e em quem acreditar. Afinal, a palavra da autoridade que deveria libertar (da pandemia) não se alinhou às pesquisas científicas e às recomendações da Organização Mundial de Saúde, ressoando contradições, inverdades e desinformação

Presence and distribution of the African citrus psyllid in São Tomé island

The African citrus psyllid, Trioza erytreae (Hemiptera: Triozidae), is a natural vector of Candidatus Liberibacter spp., the causal agents of the citrus greening disease or Huanglongbing (HLB). Despite the global losses of the Citrus industry due to HLB, the vector is rapidly spread to new areas threatening citrus crops and raising con-cern for stakeholders. Until now, there was a single old register of T. er y treae from the São Tomé island (Bulletin of the British Museum of Natural History, Entomology, 49, 1–102). In this work, we provide up-to-date occurrence data on the presence of T. er y treae throughout the isle of São Tomé. The identity of the captured adults was assessed and confirmed through molecular identification by sequencing a portion of the mitochondrial COI. The psyllid was found in lemon, orange and tangerine or-chards. Further monitoring is advisable to manage potential outbreaksFundação para a Ciência e a Tecnologia, Grant/Award Number: LA/P/0007/2020 and UIDB/00690/2020; H2020 Environment, Grant/Award Number: H2020- SFS- 2018- 2 Topic SFS- 05- 2018-2019-2020; Foundation for Science and Technologyinfo:eu-repo/semantics/publishedVersio

Screening of potential biocontrol bacterial against Pseudomonas savastanoi pv. savastanoi and elucidation of their mode of action

Over the last decades, the olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv), has been responsible for irreversible damages on olive orchards. Reduced vigor and stem dryness caused by this phytopathogen lead to a decrease in olive fruit production, conducting to countless losses for farmers. In this work, bacterial endophytes and epiphytes of olive tree phyllosphere were screened for the suppression of Psv, and several mechanisms behind this activity was also studied by evaluating indoleacetic acid (IAA), siderophore and lytic enzymes production. Interspecific interaction was assessed on solid media with agar overlays. IAA was estimated spectrophotometrically, whereas siderophores and lytic enzymes were evaluated qualitatively. Several bacterial species tested showed to reduce Psv growth up to 70%, as well as its viability. The highest inhibition was observed for Frondihabitans sp. and Paenibacillus sp. A reduction on production of both IAA and siderophore, which are associated with knot development, by Psv was noticed in the presence of the most efficient bacterial. Production of lytic enzymes by antagonists such as lipase, chitinase, protease and amylase was also identified. Altogether the results indicate that some of the bacterial tested have great potential as biocontrol agents due to their capacity to produce metabolites/lytic enzymes that can interfere with Psv growth and/or development of knots. These potential biological agents should be further evaluated under natural conditions.This work is funded by FEDER funds through COMPETE (Programa Operacional Factores de Competitividade) and by national funds by FCT (Fundação para a Ciência e a Tecnologia) in the framework of the project EXCL/AGR-PRO/0591/2012. D. MINA thanks the Fundação para a Ciência e Tecnologia (FCT), Portugal for the Ph.D. grant SFRH/BD/105341/2014info:eu-repo/semantics/publishedVersio