DIBOA in wild Poaceae: Sources of resistance to the Russian wheat aphid (Diuraphis noxia) and the greenbug (Schizaphis graminum)

Hydroxamic acids are secondary metabolites typical of Poaceae that play a role in cereal resistance against pests and pathogens. The content of the hydroxamic acid aglucones DIBOA (2,4-dihydroxy-1,4-benzoxazin-3-one) and DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) was evaluated in wild Poaceae belonging to the tribes Triticeae (genera Hordeum and Elymus) and Aveneae (genera Deschampsia and Phalaris). The concentration of DIBOA in seedling extracts of the wild barleys Hordeum chilense, H. brevisubulatum subsp. violaceum and H. bulbosum was negatively correlated with parameters related to performance of the cereal aphids Schizaphis graminum and Diuraphis noxia. The relevance of the results obtained for breeding programs aimed at increasing cereal resistance against aphids is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rachis brittleness in a hybrid–parent barley (Hordeum vulgare) breeding germplasm with different combinations at the non-brittle rachis genes

Two dominant, closely linked and complementary genes, Btr1 and Btr2, control rachis brittleness in barley. Recessive mutations in any of these genes turn the fragile rachis (brittle) into a tough rachis phenotype (non-brittle). The cross of parents with alternative mutations in the btr genes leads to a brittle F₁ hybrid that presents grain retention problems. We evaluated rachis fragility through a mechanical test and under natural conditions, in F₁ crosses with different compositions at the btr genes. Brittleness was significantly higher in Btr1btr1Btr2btr2 crosses compared to hybrids and inbred parents carrying one of the mutations (btr1btr1Btr2Btr2/Btr1Btr1btr2btr2). This fact could jeopardize the efficient harvest of hybrids bearing alternative mutations, reducing the choice of possible crosses for hybrid barley breeding and hindering the exploitation of potential heterotic patterns. Furthermore, non-brittle hybrids showed higher brittleness than inbreds, suggesting the presence of other dominant factors affecting the trait. In conclusion, this work encourages a deeper study of the genetic control of the rachis brittleness trait and urges the consideration of rachis tenacity as a target for hybrid barley breeding.     

Resistance to powdery mildew in one Spanish barley landrace hardly resembles other previously identified wild barley resistances

Two major quantitative trait loci (QTLs) associated with resistance to powdery mildew (Blumeria graminis f. sp. hordei) were previously identified on chromosome 7H of the Spanish barley line SBCC097. The two QTLs seemed to share the same chromosomal position as the major genes mlt and Mlf, which were formerly described in Hordeum vulgare ssp. spontaneum-derived lines. In the present work, different lines that carry mlt (RS42-6*O), Mlf (RS137-28*E), or a combination of both (SI-4 and SI-6) were compared with SBCC097 to evaluate their relatedness at the phenotypic, cellular, and genetic levels. The resistance of the lines was characterised by inoculating them with a set of 27 isolates of B. graminis, which displayed a wide range of virulence. It was revealed that SBCC097 possessed a distinctive resistance spectrum. Microscopic assessment of the cytological development of the resistance response showed that SBCC097 clearly formed fewer well-established colonies and secondary hyphae than the other lines. This was confirmed by the infection type recorded after visual inspection. Genetic analyses of all five lines, based on markers flanking the QTLs derived from SBCC097, supported the macroscopic and microscopic data and pointed to the presence of a combination of novel genes or alleles in SBCC097, which may be included in the category of “intermediate-acting” genes, governing resistance mainly at the post-penetration stage.     

Effects of solid phase from pig slurry on soil chemical characteristics,nitrate leaching,composition, and yield of wheat

A two years lysimeter experiment was carried out using wheat plants (Triticum aestivum L. cv. Lotti) on two texturally contrasting soils. The main purpose of this study was to evaluate the influence of increasing applications (5,10, 15,20, and 25 t.ha^‐1) of solid phase (SP) from pig slurry on soil nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) content, nitrate‐N (NO₃‐N) leaching as well as on wheat composition and yield. As the control, a basic dressing of NPK fertilizer was applied. Results showed that plant growth was stimulated by increasing amounts of SP, yet the additions of 15 to 20 t SP ha^‐1 led to similar effects on yield as that for the control. An accumulation of P on both soils was observed as well as a significant increase on NO₃‐N leaching due to increasing rates of SP added to the soils. The N and P content in wheat plants (straw and grain) increased with increasing rates of applied SP.     

Cotyledon thermal behavior and pectic solubility as related to cooking quality in common beans

The characteristic of proteins, starch and pectic substances in cotyledons of two bean cultivars varying in cooking time were determined to investigate their possible contribution to bean cooking quality. Both cultivars showed the same enthalpies of starch gelatinization but different protein denaturation enthalpies. The proportion of hot water soluble pectins was higher in Michigan, the cultivar with the lower cooking time, than in Ojo de Cabra, the cultivar with the higher cooking time. These results were not due to differences in pectin methylation or in the ratio of monovalent to divalent cations in the tissue, suggesting that in fresh beans the β-elimination reaction is not the sole or predominant route of thermal pectin degradation. Overall, this study indicates that varietal differences in bean cooking quality may be reflections of the rate of pectin loss during soaking/heating and that the thermal properties of starch and protein fractions seem to have a minor contribution. Researchers involved in this study propose that in fresh beans, the thermal pectin loss results from a two step mechanism: pectin enzymic breakdown during the bean soaking followed by thermal solubilization rather than β-elimination during the bean heating.     

The Influence of Biofilm Treatment Systems on Particle Size Distribution in Three Wastewater Treatment Plants

This article presents the results of a research study that analyzed the effect that secondary biofilm treatment systems had on particle size distribution (PSD) in the effluent of wastewater treatment plants. This study focused on three biofilm technologies (i.e. a submerged biofilter system, a trickling filter system, and a rotating biological contactor system) in three working urban wastewater treatment plants. For this purpose, the variation of the fit parameters was analyzed after modeling the PSD with the power law. The greatest reduction in particle number was obtained with the submerged biofilter system, followed by the trickling filter system. In contrast, the rotating biological contactor showed the smallest reduction in particle number under the conditions of our study. It was also found that the variation of the fit parameters of the PSD, caused by the wastewater treatments was related to other wastewater parameters, such as the chemical oxygen demand, suspended solids, and the mean particle size. This showed a direct relation between these parameters and the particles in wastewater.     

Characterization and pathogenicity of Fusarium solani causing foot rot on hemp (Cannabis sativa L.) in Southern Italy

Journal of Plant Diseases and Protection - Symptoms of foot rot were observed on hemp (Cannabis sativa) plants in Campania region (Southern Italy) in 2018. The symptoms consisted of brownish areas...     

The age of parana flood volcanism, rifting of gondwanaland, and the jurassic-cretaceous boundary

The Paraná-Etendeka flood volcanic event produced approximately 1.5 x 10(6) cubic kilometers of volcanic rocks, ranging from basalts to rhyolites, before the separation of South America and Africa during the Cretaceous period. New (40)Ar/(39)Ar data combined with earlier paleomagnetic results indicate that Paraná flood volcanism in southern Brazil began at 133 +/- 1 million years ago and lasted less than 1 million years. The implied mean eruption rate on the order of 1.5 cubic kilometers per year is consistent with a mantle plume origin for the event and is comparable to eruption rates determined for other well-documented continental flood volcanic events. Paraná flood volcanism occurred before the initiation of sea floor spreading in the South Atlantic and was probably precipitated by uplift and weakening of the lithosphere by the Tristan da Cunha plume. The Parana event postdates most current estimates for the age of the faunal mass extinction associated with the Jurassic-Cretaceous boundary.     

Subunit influenza vaccine candidate based on CD154 fused to HAH5 increases the antibody titers and cellular immune response in chickens

World Health Organization has a great concern about the spreading of avian influenza virus H5N1. To counteract its massive spread, poultry vaccination is highly recommended together with biosecurity measures. In our study, a recombinant vaccine candidate based on the fusion of extracellular segments of hemagglutinin (HA) H5 of avian influenza virus and chicken CD154 (HACD) is tested with the aim of enhancing humoral and cellular immune responses in chickens. Protein expression was carried out by transducing several mammalian cell lines with recombinant adenoviral vectors. HACD purification was assessed by three distinct purification protocols: immunoaffinity chromatography by elution at acidic pH or with a chaotropic agent and size exclusion chromatography. Humoral and cellular immune responses were measured using the hemagglutination inhibition assay and the semiquantitative real time PCR, respectively. The results showed that humoral response against HACD was significantly higher than the obtained with HA alone after booster (P<0.01, P<0.05). From HACD molecules purified by distinct protocols, only the obtained by size exclusion chromatography generated hemagglutinationin-inhibition activity. IFN-γ levels indicated that cellular immune response was significantly higher with HACD, in its pure or impure form, compared to its counterpart HA (P<0.01). These data demonstrate that HACD is able to significantly enhance humoral and cellular immune responses against HA antigen, which make this fusion protein a promising subunit vaccine candidate against H5N1 virus outbreaks.