Factor analysis applied in genomic selection studies in the breeding of Coffea canephora

Euphytica - Head splitting is a major physiological disease in cabbage. The most effective approach for controlling head splitting is to deploy genetic resistance by breeding cabbage cultivars with...     

Annual dynamics of Zymoseptoria tritici populations in wheat cultivar mixtures: A compromise between the efficacy and durability of a recently broken-down resistance gene?

Cultivar mixtures slow polycyclic epidemics but may also affect the evolution of pathogen populations by diversifying the selection pressures exerted by their plant hosts at field scale. We compared the dynamics of natural populations of the fungal pathogen Zymoseptoria tritici in pure stands and in three binary mixtures of wheat cultivars (one susceptible cultivar and one cultivar carrying the recently broken-down Stb16q gene) over two annual field epidemics. We combined analyses of population “size” based on disease severity, and of population “composition” based on changes in the frequency of virulence against Stb16q in seedling assays with more than 3000 strains. Disease reductions were observed in mixtures late in the epidemic, at the whole-canopy scale and on both cultivars, suggesting the existence of a reciprocal protective effect. The three cultivar proportions in the mixtures (0.25, 0.5, and 0.75) modulated the decrease in (a) the size of the pathogen population relative to the two pure stands, (b) the size of the virulent subpopulation, and (c) the frequency of virulence relative to the pure stand of the cultivar carrying Stb16q. Our findings suggest that optimal proportions may differ slightly between the three indicators considered. We argue potential trade-offs that should be taken into account when deploying a resistance gene in cultivar mixtures: between the dual objectives “efficacy” and “durability,” and between the “size” and “frequency” of the virulent subpopulation. Based on current knowledge, it remains unclear whether virulent subpopulation size or frequency has the largest influence on interepidemic virulence transmission.     

Deletions in the pyruvate pathway of Salmonella Typhimurium alter SPIl-mediated gene expression and infectivity

Background： Salmonella enter/ca serovar Typhimurium is a major foodborne pathogen worldwide. S. Typhimurium encodes type III secretion systems via Salmonella pathogenicity islands （SPI）, producing the major effector proteins of virulence. Previously, we identified two genes of Salmonella pyruvate metabolism that were up-regulated during chicken cell infection： pyruvate formate lyase I （pf/B） and b/functional acetaldehyde-CoA/alcohol dehydrogenase （adhE）. We were therefore interested in examining the role these genes may play in the transmission of Salmonella to humans. Methods： Mutant strains of Salmonella with single gene deletions for pflB and adhE were created. Invasion and growth in human HCT-8 intestinal epithelial cells and THP-1 macrophages was examined. Quantitative PCR was performed on 19 SPI-1 genes. Results： In HCT-8 cells, both mutant strains had significantly higher intracellular counts than the wild-type from 4 to 48 h post-infection. Various SPI-1 genes in the mutants were up-regulated over the wild-type as early as 1 h and lasting until 24 h post-infection. In THP-1 cells, no significant difference in internal Salmonella counts was observed; however, SPI-1 genes were largely down-regulated in the mutants during the time-course of infection. We also found five SPI-1 genes - hilA, hiIC hill）, sicP and rtsA - which were up-regulated in at least one of the mutant strains in log-phase broth cultures alone. We have therefore identified a set of SPI-1 virulence genes whose regulation is effected by the central metabolism of Salmonella.     

Mucosal mRNA Cytokines’ Profile of Gastric Wall in Neonatal Foals: Comparison with Endoscopy and Histology

Gastritis and gastric ulcerations occur frequently in neonatal foals. The relationship between cytokines expressed by gastric mucosa and gastric histopathology in healthy or sick foals has never been investigated. The aim of this study was to compare the histological diagnosis and endoscopic view with cytokine expression (TNF-α, IL-1β, IL-4, IL-8, IL-13, and IFN-γ) of gastric mucosa. Twenty-two foals were definitively enrolled in the study: 19 were critically ill, and 3 were healthy foals. Gastric biopsy specimens were collected for histological examination and for cytokine mRNA qualitative real-time PCR analysis. This study shows that there is a substantial agreement between histology and endoscopy and that foals with evidence of gastritis and gastric ulcerations have higher probability of expressing TNF-α. Moreover, the overall profile of cytokines expression, with a low percentage of IFN-γ, a high percentage of IL-4, and the absence of IL-13, suggests a down-regulation of the Th1 cell-mediated immune response and an impaired Th2 response in the gastric wall in the neonatal period.     

Technical and Economic Analysis of Aeroponics and other Systems for Potato Mini-Tuber Production in Latin America

Producing large quantities of high quality mini-tubers at low cost is essential for an economically viable supply of seed potatoes. Here we systematize the technical and economic aspects of aeroponics and provide a benchmark comparison of this technology with other mini-tuber production systems as developed in Latin America: conventional, semi-hydroponics, and fiber-cement tiles technology. Research methodologies included: 3-year registration of cash flows and production registers of aeroponics, economic and technical surveys, in-depth inquiry with managers of technologies. Results show that aeroponics as promoted by the International Potato Center (CIP) has several advantages, including high multiplication rates (up to 1:45), high production efficiency per area (> 900 mini-tubers per m²), savings in water, chemicals and/or energy, and positive economic indicators. The fiber-cement tiles technology from Brazil is also shown to be highly efficient and slightly more robust compared to aeroponics. Preconditions for the successful adoption of the different technologies in developing countries are discussed.     

Prohibitin,an essential protein for Colorado potato beetle larval viability,is relevant to Bacillus thuringiensis Cry3Aa toxicity

Bacillus thuringienesis (Bt) Cry toxins constitute the most extensively used environmentally safe biopesticide and their mode of action relies on the interaction of the toxins with membrane proteins in the midgut of susceptible insects that mediate toxicity and insect specificity. Therefore, identification of Bt Cry toxin interacting proteins in the midgut of target insects and understanding their role in toxicity is of great interest to exploit their insecticidal action. Using ligand blot, we demonstrated that Bt Cry3Aa toxin bound to a 30 kDa protein in Colorado potato beetle (CPB) larval midgut membrane, identified by sequence homology as prohibitin-1 protein. Prohibitins comprise a highly conserved family of proteins implicated in important cellular processes. We obtained the complete CPB prohibitin-1 DNA coding sequence of 828 pb, in silico translated into a 276-amino acid protein. The analysis at the amino acid level showed that the protein contains a prohibitin-homology domain (Band7_prohibitin, cd03401) conserved among prohibitin proteins. A striking feature of the CPB identified prohibitin-1 is the predicted presence of cadherin elements, potential binding sites for Cry toxins described in other Bt susceptible insects. We also showed that CPB prohibitin-1 protein partitioned into both, detergent soluble and insoluble membrane fractions, as well as a prohibitin-2 homologous protein, previously reported to form functional complexes with prohibitin-1 in other organisms. Prohibitin complexes act as membrane scaffolds ensuring the recruitment of membrane proteases to facilitate substrate processing. Accordingly, sequestration of prohibitin-1 by an anti-prohibitin-1 antibody impaired the Cry3Aa toxin inhibition of the proteolytic cleavage of a fluorogenic synthetic substrate of an ADAM-like metalloprotease previously reported to proteolize this toxin. In this work, we also demonstrated that prohibitin-1 RNAi silencing in CPB larvae produced deleterious effects and together with a LD50 Cry3Aa toxin treatment resulted in a highly efficient short term response since 100% larval mortality was achieved just 5 days after toxin challenge. Therefore, the combination of prohibitin RNAi and Cry toxin reveals as an effective strategy to improve crop protection.     

Heterodera elachista the Japanese cyst nematode parasitizing corn in Northern Italy: integrative diagnosis and bionomics

The Japanese cyst nematode Heterodera elachista was detected parasitizing corn cv Rixxer in Bosco Mesola (Ferrara Province) in Northern Italy. The only previous report of this nematode was in Asia (Japan, China and Iran) attacking upland rice; being this work the first report of this cyst nematode in Europe, and confirmed corn as a new host plant for this species. Integrative morphological and molecular data for this species were obtained using D2-D3 expansion regions of 28S rDNA, ITS1-rDNA, the partial 18S rDNA, the protein-coding mitochondrial gene, cytochrome oxidase c subunit I (COI), and the heat-shock protein 90 (hsp90). Heterodera elachista identified in Northern Italy was morphologically and molecularly clearly separated from other cyst nematodes attacking corn (viz. H. avenae, H. filipjevi, H. delvii, H. oryzae, H. sacchari, H. sorghi, H. zeae, Punctodera chalcoensis, and Vittadera zeaphila) and rice (H. oryzae, H. sacchari). The phylogenetic relationships of H. elachista from Northern Italy with other cyst-nematodes using rDNA and mtDNA showed a separation of the genus Heterodera in various morphospecies groups based on vulval cone structures. The development and parasitic habit of H. elachista on naturally infected corn cv Rixxer confirmed a typical susceptible reaction, including multinucleate syncytial cells in parenchymatic cells. Under greenhouse conditions, H. elachista successfully reproduced on two crops widely used in Northern Italy, such as corn (cv PR 33) and rice (cv Baldo). Considering the limited host-range of this nematode, that include two of the three world’s most important crops, special attention is needed for avoiding the dispersal of this nematode into new areas, by movement of soil on equipment, water, and contaminated containers infested soil, or agricultural practices.     

Leaf physiological and anatomical characters contribute to drought tolerance of Nusa Tenggara Timur local rice cultivars

Journal of Crop Science and Biotechnology - Morpho-anatomical characters supporting the resilience of a plant under certain environmental conditions cannot be interpreted individually but...