Characterization of new IS elements and studies of their dispersion in two subspecies of Leifsonia xyli

<p>Abstract</p> <p>Background</p> <p><it>Leifsonia xyli </it>is a xylem-inhabiting bacterial species comprised of two subspecies: <it>L. xyli </it>subsp. <it>xyli </it>(<it>Lxx</it>) and <it>L. xyli </it>subsp. <it>cynodontis </it>(<it>Lxc</it>). <it>Lxx </it>is the causal agent of ratoon stunting disease in sugarcane commercial fields and <it>Lxc </it>colonizes the xylem of several grasses causing either mild or no symptoms of disease. The completely sequenced genome of <it>Lxx </it>provided insights into its biology and pathogenicity. Since IS elements are largely reported as an important source of bacterial genome diversification and nothing is known about their role in chromosome architecture of <it>L. xyli</it>, a comparative analysis of <it>Lxc </it>and <it>Lxx </it>elements was performed.</p> <p>Results</p> <p>Sample sequencing of <it>Lxc </it>genome and comparative analysis with <it>Lxx </it>complete DNA sequence revealed a variable number of IS transposable elements acting upon genomic diversity. A detailed characterization of <it>Lxc </it>IS elements and a comparative review with IS elements of <it>Lxx </it>are presented. Each genome showed a unique set of elements although related to same IS families when considering features such as similarity among transposases, inverted and direct repeats, and element size. Most of the <it>Lxc </it>and <it>Lxx </it>IS families assigned were reported to maintain transposition at low levels using translation regulatory mechanisms, consistent with our <it>in silico </it>analysis. Some of the IS elements were found associated with rearrangements and specific regions of each genome. Differences were also found in the effect of IS elements upon insertion, although none of the elements were preferentially associated with gene disruption. A survey of transposases among genomes of Actinobacteria showed no correlation between phylogenetic relatedness and distribution of IS families. By using Southern hybridization, we suggested that diversification of <it>Lxc </it>isolates is also mediated by insertion sequences in probably recent events.</p> <p>Conclusion</p> <p>Collectively our data indicate that transposable elements are involved in genome diversification of <it>Lxc </it>and <it>Lxx</it>. The IS elements were probably acquired after the divergence of the two subspecies and are associated with genome organization and gene contents. In addition to enhancing understanding of IS element dynamics in general, these data will contribute to our ongoing comparative analyses aimed at understanding the biological differences of the <it>Lxc </it>and <it>Lxx</it>.</p

Inheritance of resistance to Puccinia psidii G. Winter in a eucalyptus interspecific hybrid progeny evaluated under conditions of natural infection

A ferrugem, causada pelo fungo Puccinia psidii, é atualmente a mais importante doença do eucalipto. Esta doença está amplamente disseminada pelo Brasil e causa sérios danos em viveiros e plantações. A identificação de germoplasma resistente aliado ao conhecimento da base genética da resistência são os requerimentos primordiais para o sucesso de programas de melhoramento visando à produção de cultivares resistentes. Estudos anteriores sobre a herança da resistência em condições controladas sugerem tanto uma herança monogênica como a participação de pelo menos 2 genes conferindo resistência à doença. O objetivo deste estudo foi avaliar a resistência a P. psidii, em condições de campo em quatorze progênies obtidas a partir de cruzamentos e auto-cruzamentos controlados entre quatro clones híbridos de Eucalyptus grandis Hill ex Maiden x Eucalyptus urophylla ST Blake,que contrastam para a resistência ao fungo. Os resultados indicam que a resistência pode ser explicada por um loco com efeito principal e pelo menos três alelos diferentes, com interações entre os alelos, resultando no fenótipo de resistência ou suscetibilidade. Entretanto, locos com menor efeito devem influenciar a resistência, uma vez que foram observadas variações nas classes de severidade da escala utilizada. Nenhuma diferença na segregação para a resistência foi observada entre cruzamentos recíprocos, sugerindo que não existe influência citoplasmática no controle deste caráter.Rust caused by the fungus Puccinia psidii is currently the most important disease of eucalyptus. It is widely disseminated in Brazil, and causes serious damage in nurseries and plantation areas. The identification of resistant germplasm along with knowledge of the genetic basis of resistance heredity are the first requirements for the success of breeding programs aiming to develop resistant varieties. Earlier studies carried out under controlled conditions suggested a monogenic control as well as the participation of at least two genes promoting resistance to rust. The goal of this study was to evaluate the resistance to P. psidii under field conditions in fourteen progenies from controlled crosses and self-crosses among four hybrid clones of Eucalyptus grandis Hill ex Maiden x Eucalyptus urophylla ST Blake that contrast for resistance to the fungus. Results indicated that resistance could be explained by one locus with main effects and at least three different alleles. However, loci with minor effects may influence the resistance, since variation on severity classes was observed. Differences in segregation of resistance between reciprocal crosses were not observed, indicating absence of cytoplasmic effects.Votorantim Celulose e PapelConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

When enough should be enough: Improving the use of current agricultural lands could meet production demands and spare natural habitats in Brazil

Providing food and other products to a growing human population while safeguarding natural ecosystems and the provision of their services is a significant scientific, social and political challenge. With food demand likely to double over the next four decades, anthropization is already driving climate change and is the principal force behind species extinction, among other environmental impacts. The sustainable intensification of production on current agricultural lands has been suggested as a key solution to the competition for land between agriculture and natural ecosystems. However, few investigations have shown the extent to which these lands can meet projected demands while considering biophysical constraints. Here we investigate the improved use of existing agricultural lands and present insights into avoiding future competition for land. We focus on Brazil, a country projected to experience the largest increase in agricultural production over the next four decades and the richest nation in terrestrial carbon and biodiversity. Using various models and climatic datasets, we produced the first estimate of the carrying capacity of Brazil's 115 million hectares of cultivated pasturelands. We then investigated if the improved use of cultivated pasturelands would free enough land for the expansion of meat, crops, wood and biofuel, respecting biophysical constraints (i.e., terrain, climate) and including climate change impacts. We found that the current productivity of Brazilian cultivated pasturelands is 32–34% of its potential and that increasing productivity to 49–52% of the potential would suffice to meet demands for meat, crops, wood products and biofuels until at least 2040, without further conversion of natural ecosystems. As a result up to 14.3 Gt CO2 Eq could be mitigated. The fact that the country poised to undergo the largest expansion of agricultural production over the coming decades can do so without further conversion of natural habitats provokes the question whether the same can be true in other regional contexts and, ultimately, at the global scale

Nut production in Bertholletia excelsa across a logged forest mosaic: implications for multiple forest use

Although many examples of multiple-use forest management may be found in tropical smallholder systems, few studies provide empirical support for the integration of selective timber harvesting with non-timber forest product (NTFP) extraction. Brazil nut (Bertholletia excelsa, Lecythidaceae) is one of the world’s most economically-important NTFP species extracted almost entirely from natural forests across the Amazon Basin. An obligate out-crosser, Brazil nut flowers are pollinated by large-bodied bees, a process resulting in a hard round fruit that takes up to 14 months to mature. As many smallholders turn to the financial security provided by timber, Brazil nut fruits are increasingly being harvested in logged forests. We tested the influence of tree and stand-level covariates (distance to nearest cut stump and local logging intensity) on total nut production at the individual tree level in five recently logged Brazil nut concessions covering about 4000 ha of forest in Madre de Dios, Peru. Our field team accompanied Brazil nut harvesters during the traditional harvest period (January-April 2012 and January-April 2013) in order to collect data on fruit production. Three hundred and ninety-nine (approximately 80%) of the 499 trees included in this study were at least 100 m from the nearest cut stump, suggesting that concessionaires avoid logging near adult Brazil nut trees. Yet even for those trees on the edge of logging gaps, distance to nearest cut stump and local logging intensity did not have a statistically significant influence on Brazil nut production at the applied logging intensities (typically 1–2 timber trees removed per ha). In one concession where at least 4 trees ha-1 were removed, however, the logging intensity covariate resulted in a marginally significant (0.09) P value, highlighting a potential risk for a drop in nut production at higher intensities. While we do not suggest that logging activities should be completely avoided in Brazil nut rich forests, when a buffer zone cannot be observed, low logging intensities should be implemented. The sustainability of this integrated management system will ultimately depend on a complex series of socioeconomic and ecological interactions. Yet we submit that our study provides an important initial step in understanding the compatibility of timber harvesting with a high value NTFP, potentially allowing for diversification of forest use strategies in Amazonian Perù

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Cloning and endogenous expression of a Eucalyptus grandis UDP-glucose dehydrogenase cDNA

UDP-glucose dehydrogenase (UGDH) catalyzes the oxidation of UDP-glucose (UDP-Glc) to UDP-glucuronate (UDP-GlcA), a key sugar nucleotide involved in the biosynthesis of plant cell wall polysaccharides. A full-length cDNA fragment coding for UGDH was cloned from the cambial region of 6-month-old E. grandis saplings by RT-PCR. The 1443-bp-ORF encodes a protein of 480 amino acids with a predicted molecular weight of 53 kDa. The recombinant protein expressed in Escherichia coli catalyzed the conversion of UDP-Glc to UDP-GlcA, confirming that the cloned cDNA encodes UGDH. The deduced amino acid sequence of the cDNA showed a high degree of identity with UGDH from several plant species. The Southern blot assay indicated that more than one copy of UGDH is present in Eucalyptus. These results were also confirmed by the proteomic analysis of the cambial region of 3- and 22-year-old E. grandis trees by 2-DE and LC-MS/MS, showing that at least two isoforms are present. The cloned gene is mainly expressed in roots, stem and bark of 6-month-old saplings, with a lower expression in leaves. High expression levels were also observed in the cambial region of 3- and 22-year-old trees. The results described in this paper provide a further view of the hemicellulose biosynthesis during wood formation in E. grandis

Results on stellar occultations by (307261) 2002 MS4

Transneptunian Objects (TNOs) are the remnants of our planetary system and can retain information about the early stages of the Solar System formation. Stellar occultation is a groundbased method used to study these distant bodies which have been presenting exciting results mainly about their physical properties. The big TNO called 2002 MS4 was discovered by Trujillo, C. A., &amp; Brown, M. E., in 2002 using observations made at the Palomar Observatory (EUA). It is classified as a hot classical TNO, with orbital parameters a = 42 AU, e = 0.139, and i = 17.7º. Using thermal measurements with PACS (Herschel) and MIPS (Spitzer Space Telescope) instruments, Vilenius et al. 2012 obtained a radius of 467 +/- 23.5 km and an albedo of 0.051.Predictions of stellar occultations by this body in 2019 were obtained using the Gaia DR2 catalogue and NIMA ephemeris (Desmars et al. 2015) and made available in the Lucky Star web page (https://lesia.obspm.fr/lucky-star/). Four events were observed in South America and Canada. The first stellar occultation was detected on 09 July 2019, resulting in two positives and four negatives chords, including a close one which proven to be helpful to constrain the body’s size. This detection also allowed us to obtain a precise astrometric position that was used to update its ephemeris and improve the predictions of the following events. Two of them were detected on 26 July 2019, separated by eight hours. The first event was observed from South America and resulted in three positive detections, while the second, observed from Canada, resulted in a single chord. Another double chord event was observed on 19 August 2019 also from Canada.Facultad de Ciencias Astronómicas y Geofísica

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Unidad de excelencia María de Maeztu CEX2019-000940-MAim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types