Obtención de suero anti-Rice stripe necrosis virus por expresión heteróloga de la capside proteica viral

PosterEl entorchamiento del arroz”, causado por el Rice stripe necrosis virus ( es una gran amenaza para el cultivo del arroz en Argentina Hasta la fecha, se desconoce su distribución, cultivares promisoriamente resistentes y no se cuenta con un suero comercial para su detección El objetivo de este trabajo fue la obtención de suero anti RSNV para la detección del virus en un gran número de muestras en simultaneo y de bajo costo.Instituto de Patología VegetalFil: Celli, Marcos Giovani. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Fitopatología y Modelización Agrícola (UFyMA); ArgentinaFil: Celli, Marcos Giovani. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Bangratz, M. INRAE. CIRAD. Institut de Recherche pour le Développement (IRD); FranciaFil: Pinel Galzi, A. INRAE. CIRAD. Institut de Recherche pour le Développement (IRD); FranciaFil: Brizard, J.P. INRAE. CIRAD. Institut de Recherche pour le Développement (IRD); FranciaFil: Hébrard, E. INRAE. CIRAD. Institut de Recherche pour le Développement (IRD); FranciaFil: Brugidou, C. INRAE. CIRAD. Institut de Recherche pour le Développement (IRD); Franci

Identification of precursor transcripts for 6 novel miRNAs expands the diversity on the genomic organisation and expression of miRNA genes in rice

<p>Abstract</p> <p>Background</p> <p>The plant miRNAs represent an important class of endogenous small RNAs that guide cleavage of an mRNA target or repress its translation to control development and adaptation to stresses. MiRNAs are nuclear-encoded genes transcribed by RNA polymerase II, producing a primary precursor that is subsequently processed by DCL1 an RNase III Dicer-like protein.</p> <p>In rice hundreds of miRNAs have been described or predicted, but little is known on their genes and precursors which are important criteria to distinguish them from siRNAs. Here we develop a combination of experimental approaches to detect novel miRNAs in rice, identify their precursor transcripts and genes and predict or validate their mRNA targets.</p> <p>Results</p> <p>We produced four cDNA libraries from small RNA fractions extracted from distinct rice tissues. By <it>in silico </it>analysis we selected 6 potential novel miRNAs, and confirmed that their expression requires OsDCL1. We predicted their targets and used 5'RACE to validate cleavage for three of them, targeting a PPR, an SPX domain protein and a GT-like transcription factor respectively.</p> <p>In addition, we identified precursor transcripts for the 6 miRNAs expressed in rice, showing that these precursors can be efficiently processed using a transient expression assay in transfected <it>Nicotiana benthamiana </it>leaves. Most interestingly, we describe two precursors producing tandem miRNAs, but in distinct arrays. We focus on one of them encoding osa-miR159a.2, a novel miRNA produced from the same stem-loop structure encoding the conserved osa-miR159a.1. We show that this dual osa-miR159a.2-osa-miR159a.1 structure is conserved in distant rice species and maize. Finally we show that the predicted mRNA target of osa-miR159a.2 encoding a GT-like transcription factor is cleaved <it>in vivo </it>at the expected site.</p> <p>Conclusion</p> <p>The combination of approaches developed here identified six novel miRNAs expressed in rice which can be clearly distinguished from siRNAs. Importantly, we show that two miRNAs can be produced from a single precursor, either from tandem stem-loops or tandemly arrayed in a single stem-loop. This suggests that processing of these precursors could be an important regulatory step to produce one or more functional miRNAs in plants and perhaps coordinate cleavage of distinct targets in the same plant tissue.</p

Heredity and genetic mapping of domestication-related traits in a temperate Japonica weedy rice

Rice is often found as various weedy forms in temperate or newly cultivated rice growing regions throughout the world. The emergence of these forms in the absence of true wild rice remains unclear. A genetic analysis of domestication-related traits (weed syndrome) has been conducted to better understand the appearance of these plants in rice fields. A doubled haploid (DH) population was derived from a cross between a #japonica variety and a weedy plant collected in Camarque (France) to set up a genetic linkage map consisting of 68 SSR and 31 AFLP loci. Five qualitative traits related to pigmentation of different organs and 15 developmental and morphological quantitative traits were scored for genes and QTLs mapping. Despite a good reactivity in another culture and a high fertility of DH lines, segregation distortions were observed on chromosonal segments bearing gametophytic and sterility genes and corresponded to various QTLs evidenced in #indica x #japonica distant crosses. Mapping of the coloration genes was found to be in agreement with the presence of several genes previously identified and according to the genetic model governing the synthesis and distribution of anthocyan pigment in the plant. In addition, the main specific traits of weedy forms revealed the same genes/QTLs as progeny derived from a cross between #Oryza sativa and its wild progenitor #O. rufipogon$. A large variation for most characters was found in the DH population, including transgressive variation. Significant correlations were observed between morphology and traits related to weeds and corresponded to a distinct colocalization of most of the QTLs on a limited number of chromosomal regions. The significance of these results on the origin of weedy forms and the de-domestication process is discussed. (Résumé d'auteur

A preliminary assessment of a combination of rhodiola and saffron in the management of mild&ndash;moderate depression

Marie Bangratz,1 Samira Ait Abdellah,1 Aur&eacute;lie Berlin,1 Claude Blondeau,1 Ang&egrave;le Guilbot,1 Michel Dubourdeaux,1 Patrick Lemoine2 1Groupe PiLeJe, Paris, France; 2Clinique Lyon Lumi&egrave;re, Meyzieu, France Objective: The medicinal plants Rhodiola rosea L. (rhodiola, golden root) and Crocus sativus L. (saffron) have been shown separately to induce significant effects in depression. The objective of this study was to assess a fixed combination of rhodiola and saffron in mild&ndash;moderate depression.Methods: In this observational study conducted with general practitioners (GPs), 45 adults (aged 18&ndash;85 years) suffering from mild or moderate depression (International Statistical Classification of Diseases and Related Health Problems 10th Revision definition) and reaching a score on the Hamilton Rating Scale for Depression of 8&ndash;18 were supplemented with a combination of rhodiola and saffron extracts (one tablet, 154 mg of rhodiola and 15 mg of saffron; recommended dose two tablets per day for 6 weeks).Results: After 6 weeks (D42) of supplementation, Hamilton Rating Scale for Depression scores (primary outcome) decreased significantly by 58%&plusmn;28.5% (from 13.6&plusmn;2.3 at D0 to 5.6&plusmn;3.8 at D42, P&lt;0.0001; n=41). Score improvement was reported in 85.4% of patients. A significant drop in both Hospital Anxiety and Depression Scale anxiety and depression scores was also observed at D42, the decrease being significant from 2 weeks of supplementation. At the end of the study, both GPs and patients deemed there was a significant improvement in depression (Clinical Global Impression &ndash; improvement and Patient Global Impression of Change). Safety was excellent, and no serious adverse effects were recorded.Conclusion: Results of this observational study performed in primary care suggest that the combination of rhodiola and saffron tested could be useful for the management of mild&ndash;moderate depression and improve depressive and anxiety symptoms. A double-blind placebo-controlled study is needed to confirm these results. Keywords: major depressive disorder, anxiety, Rhodiola rosea, Crocus sativus&nbsp

Rice Yellow Mottle Virus stress responsive genes from susceptible and tolerant rice genotypes - art. no. 26

Background: The effects of viral infection involve concomitant plant gene variations and cellular changes. A simple system is required to assess the complexity of host responses to viral infection. The genome of the Rice yellow mottle virus (RYMV) is a single-stranded RNA with a simple organisation. It is the most well-known monocotyledon virus model. Several studies on its biology, structure and phylogeography have provided a suitable background for further genetic studies. 12 rice chromosome sequences are now available and provide strong support for genomic studies, particularly physical mapping and gene identification. Results: The present data, obtained through the cDNA-AFLP technique, demonstrate differential responses to RYMV of two different rice cultivars, i.e. susceptible IR64 (Oryza sativa indica), and partially resistant Azucena (O.s. japonica). This RNA profiling provides a new original dataset that will enable us to gain greater insight into the RYMV/rice interaction and the specificity of the host response. Using the SIM4 subroutine, we took the intron/exon structure of the gene into account and mapped 281 RYMV stress responsive (RSR) transcripts on 12 rice chromosomes corresponding to 234 RSR genes. We also mapped previously identified deregulated proteins and genes involved in partial resistance and thus constructed the first global physical map of the RYMV/rice interaction. RSR transcripts on rice chromosomes 4 and 10 were found to be not randomly distributed. Seven genes were identified in the susceptible and partially resistant cultivars, and transcripts were colocalized for these seven genes in both cultivars. During virus infection, many concomitant plant gene expression changes may be associated with host changes caused by the infection process, general stress or defence responses. We noted that some genes (e. g. ABC transporters) were regulated throughout the kinetics of infection and differentiated susceptible and partially resistant hosts. Conclusion: We enhanced the first RYMV/rice interaction map by combining information from the present study and previous studies on proteins and ESTs regulated during RYMV infection, thus providing a more comprehensive view on genes related to plant responses. This combined map provides a new tool for exploring molecular mechanisms underlying the RYMV/ rice interaction

Sites under positive selection modulate the RNA silencing suppressor activity of rice yellow mottle virus movement protein P1

RNA silencing is a eukaryotic mechanism for RNA-based gene regulation that plays an essential role in diverse biological processes, such as defence against viral infections. The P1 of rice yellow mottle virus (RYMV) is a movement protein and displays RNA silencing suppression activity with variable efficiency, depending on the origin of the isolates. In this study, the positive selection pressure acting on the P1 protein gene was assessed. A site-by-site analysis of the d(N)/d(S) ratio was performed and 18 positively selected sites were identified. Four of these were mutated, and the ability to suppress RNA silencing was evaluated for the resulting mutants in a transient expression assay. All mutations affected quantitatively RNA silencing suppression, one caused a significant decrease in the activity and three significantly increased it. This work demonstrates, for what is to the best of our knowledge the first time, that the RYMV gene encoding the P1 RNA silencing suppressor is under adaptive evolution

Effects of sweet potato feathery mottle virus, sweet potato chlorotic stunt virus and their co-infection on sweet potato yield in Western Burkina Faso

To determine the effects of sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV) and their co-infection on sweet potato yield, twelve sweet potato varieties were assessed in a hotspot area in Western Burkina Faso. The experiment was carried out in a randomized complete-block design with the twelve varieties in three replications. Data were collected on plant growth parameters, plant virus symptoms and yield parameters. Additional testing for selected sweet potato viruses was done using a nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) and RT-PCR. SPFMV and SPCSV were the viruses detected in this study. Varieties Djakani and Ligri were virus-free and had the highest average yields out of twelve sweet potato varieties assessed. Field monitoring indicated that 58% of plants were found to be virus-infected. The results suggest that severe symptoms were associated with sweet potato virus disease (SPVD) and yield reduction. However, the interaction of SPCSV with other viruses, which may result in synergistic negative effects on sweet potato yield and quality, needs further research