Identification of genetic regions associated with black point in barley

Black point (BP) can cause severe losses to the barley industry through downgrading and discounting of malting barley. The genetic improvement in BP resistance of barley is complex, requiring reliable screening tools, an understanding of genotype by environment interactions and an understanding of the biochemical mechanisms of melanisation involved in BP development. Thus the application of molecular markers for resistance to BP may be a useful tool for plant breeders. We have investigated the genetic regions associated with BP resistance in the barley F₂ population, Valier/Binalong. Quantitative trait loci (QTLs) contributed by the resistant parent Valier, were detected on chromosomes 2HS, 2HC, 3HL, 4HL and a QTL contributed by the susceptible parent, Binalong was detected on 5HL. Three of the four QTLs were detected in two distinctly different environments. The differences observed in BP resistance between these two environments and the implications for accelerated screening are discussed. Identified SSR markers in these regions may be useful for selecting black point resistance in related breeding materials.     

Preserving the tree of life

Phylogenies provide new ways to measure biodiversity, to assess conservation priorities, and to quantify the evolutionary history in any set of species. Methodological problems and a lack of knowledge about most species have so far hampered their use. In the future, as techniques improve and more data become accessible, we will have an expanded set of conservation options, including ways to prioritize outcomes from evolutionary and ecological processes.     

Enzyme Immunoassays for the Determination of Ovine LH and FSH

The development of competitive enzyme immunoassays for ovine plasma LH (oLH) and FSH (oFSH) is described. Standards and plasma samples were preincubated with diluted antiserum to oLH or oFSH and the reacted solution (100 μl per well) was transferred to plates previously coated with oLH or oFSH, respectively. The second antibody used was anti‐rabbit IgG horseradish peroxidase. The measuring range was 0.39–50 ng/ml for each hormone and the 50% relative binding sensitivity was 9 ng/ml for oLH. The respective value for oFSH was 3.5 or 34 ng/ml with different hormone and antibody preparations used for the assay. The enzyme immunoassays were used to determine oLH and oFSH levels in plasma from ewes of two breeds during the oestrous cycle. The assays detected the first FSH surge coincident with the LH surge, the second FSH surge about 24 h later and the periodic fluctuations of FSH concentrations during the luteal phase of the oestrous cycle. These enzyme immunoassays are an efficient and economic alternative to the established radioimmunoassays (RIA) for oLH and oFSH.     

Comparison of Gypsum and Sulfuric Acid for Sodic Soil Reclamation

In some field and laboratory studies , H2SO4 has shown better reclamation efficiency than gypsum, but the explanation for this has been debated. We tested the hypothesis that significant amounts of HCO might be formed during the reaction of HSO3 with CaCO3 leading to additional Ca2+ in solution and enhanced displacement of exchangeble Na +. To determine if H2SO4 is more efficient than gypsum , we compared four equivalent treatments of H2SO4 and gypsum on three soils and two clay minerals. Gypsum and H2SO4 were reacted with calcareous sodic soils and clay minerals in closed-system batch studies, with CO2 pressures typical of soil root zones. Column studies comparing two equivalent treatments of H2SO4 and gypsum were conducted on one of the soils and produced results comparable to the batch studies. Soluble ions, electrical conductivities (EC), and mineral saturation indices were determined and compared between treatments . Clay dispersion and average dispersed particle size were compared between amendments on bentonite . When H2SO4 was applied to calcite in the absence of exchangeable sodium (soil), the solution was fourfold oversaturated with respect to gypsum. This was not observed in the soils because the exchange phase of the soil was a sink for Ca2+. In the soils, there was significantly more HCO3 in all H2SO4 treatments, with an average of 8 % of the H+ applied producing H3CO3. The concentration of dispersed clay was significantly less in three of the four H2SO4 treatments on bentonite , while the mean particle diameter was significantly larger in two of the four treatments , suggesting better tactoid preservation . Compared to equivalent soil gypsum treat ments, H2SO4 generally caused (1) lower sodium adsorption ratios , (2) more soluble Ca 2+ and Mg2+, (3) lower pH , and (4) greater EC. In the calcareous sodic soils and clays we tested , it appears gypsum supersaturation , HCO3 production , lower pH , and higher EC frequently contributed to better reclamation with H2SO4.