Durable resistance to blast, the most significant fungal disease of rice, represents an agronomically relevant character. Gigante Vercelli (GV) and Vialone Nano (VN) are two old temperate japonica Italian rice cultivars with contrasting response to blast infection: GV displays durable and broad resistance while VN is highly susceptible. RNA-seq was used to dissect the early molecular processes deployed during the resistance response of GV at 24 h after blast inoculation. Differential gene expression analysis identified 1,070 and 1,484 modulated genes, of which 726 and 699 were up regulated in response to infection in GV and VN, respectively. Gene ontology (GO) enrichment analyses revealed a set of GO terms enriched in both varieties but, despite this commonality, the gene sets contributing to common GO enriched terms were dissimilar. The expression patterns of genes grouped in GV-specific enriched GO terms were examined in detail including at the transcript isoform level. GV exhibited a dramatic up-regulation of genes encoding diterpene phytoalexin biosynthetic enzymes, flavin-containing monooxygenase, class I chitinase and glycosyl hydrolase 17. The sensitivity and high dynamic range of RNA-seq allowed the identification of genes critically involved in conferring GV resistance during the early steps of defence perception-signalling. These included chitin oligosaccharides sensing factors, wall associated kinases, MAPK cascades and WRKY transcription factors. Candidate genes with expression patterns consistent with a potential role as GV-specific functional resistance (R) gene(s) were also identified. This first application of RNA-seq to dissect durable blast resistance supports a crucial role of the prompt induction of a battery of responses including defence-related genes as well as members of gene families involved in signalling and pathogen-related gene expression regulation.

The antifungal properties of saponin mixtures from alfalfa (Medicago sativa L.) tops and roots, the corresponding mixtures of prosapogenins from tops, and purified saponins and sapogenins against the causal agent of rice blast Pyricularia oryzae isolates are presented. In vitro experiments highlighted a range of activities, depending upon the assayed metabolite. The antifungal effects of the most promising prosapogenin mixture from alfalfa tops were confirmed by means of in planta tests using three different Italian cultivars of rice (Oryza sativa L. ssp. japonica), known to possess high, medium, and low blast resistance. The evidenced antifungal properties of the tested metabolites allowed some considerations on their structure-activity relationship. Results indicate that prosapogenins are active compounds to prevent the fungal attack of P. oryzae on different rice cultivars. Therefore, if properly formulated, these substances could represent a promising and environmentally friendly treatment to control rice blast.

Rice cultivars exhibiting durable resistance to blast, the most important rice fungal disease provoking up to 30 % of rice losses, are very rare and searching for sources of such a resistance represents a priority for rice-breeding programs. To this aim we analyzed Gigante Vercelli (GV) and Vialone Nano (VN), two temperate japonica rice cultivars in Italy displaying contrasting response to blast, with GV showing a durable and broad-spectrum resistance, whereas VN being highly susceptible. An SSR-based genetic map developed using a GV × VN population segregating for blast resistance identified two blast resistance loci, localized to the long arm of chromosomes 1 and 4 explaining more than 78 % of the observed phenotypic variation for blast resistance. The pyramiding of two blast resistance QTLs was therefore involved in the observed durable resistance in GV. Mapping data were integrated with information obtained from RNA-seq expression profiling of all classes of resistance protein genes (resistance gene analogs, RGAs) and with the map position of known cloned or mapped blast resistance genes to search candidates for the GV resistant response. A co-localization of RGAs with the LOD peak or the marker interval of the chromosome 1 QTL was highlighted and a valuable tool for selecting the resistance gene during breeding programs was developed. Comparative analysis with known blast resistance genes revealed co-positional relationships between the chromosome 1 QTL with the Pi35/Pish blast resistance alleles and showed that the chromosome 4 QTL represents a newly identified blast resistance gene. The present genetic analysis has therefore allowed the identification of two blast resistance loci in the durable blast-resistant rice cultivar GV and tools for molecular selection of these resistance genes.

BackgroundPre-eclampsia (PE) is a common disorder of pregnancy that usually presents with hypertension and proteinuria. The clinical presentation arises from soluble factors released into the maternal circulation from the placenta owing to the stress of syncytiotrophoblast, consequence of defective placentation occurring in the first half of pregnancy. Reduced tolerance of the semiallogeneic fetus by the maternal immune system has been proposed as first trigger leading to poor placentation. We previously observed aberrant expression of human leukocyte antigen (HLA)-DR molecules in the syncytiotrophoblast of a subset of women with PE. Aim of this study was to investigate abnormal expression of circulating HLA-DR in syncytiotrophoblast-derived extracellular vesicles (STBEVs) in women with PE compared to normal pregnant women.Methodsperipheral venous blood was collected from 22 women with PE and 22 normal pregnant women. Circulating STBEVs were collected by ultra-centrifugation (120000 g) and analyzed for the expression of HLA-DR and placental alkaline phosphatase (PLAP), a specific marker of the placenta, by Western blot analysis and flow cytometry.Resultscirculating STBEVs positive for HLA-DR were observed in 64% of PE women while no HLA-DR positivity was detected in any of the controls (P<0.01).ConclusionsAberrant expression of HLA-DR in circulating STBEVs is specifically associated to PE. Further studies are required: a) to define the role of aberrant placental expression of HLA-DR molecules in the pathogenesis of PE; b) evaluate a possible application of detecting circulating HLA-DR positive STBEVs in the diagnosis and prediction of PE in the first and second trimester of pregnancy.