Improvement of malting quality of barley by complementing the malt enzyme spectrum

The processing quality of cereals can be modified by altering the structural grain constituents or the enzyme activities that mobilize storage reserves of the seeds. In order to complement the malt enzyme spectrum, a gene encoding for a thermotolerant fungal endo-(1,4)--glucanase was introduced into two barley cultivars, Kymppi and Golden Promise. The gene was expressed in the seeds during germination, thus providing a thermotolerant enzyme that is active under mashing conditions. The amount of thermotolerant -glucanase produced by the seeds (ca. 0.025% soluble seed protein) has been shown to be sufficient to reduce wort viscosity by decreasing the soluble -glucan content. For the safe commercial cultivation of transgenic plants risk assessment of their cultivation is needed. In our study experimental estimates of the transgene flow from transgenic barley by pollen dispersal were produced. Field trials were conducted during the summers of 1996 and 1997. A transgenic barley line homozygous for the gene encoding for neomycin phosphotransferase was used as a source of pollen and male-sterile barley lines as recipients. In order to be able to transform the cross-fertilization frequencies to corresponding values of normal male-fertile barley, plots of normal barley were also included in the experimental plan. On the basis of our study, cross-fertilization in male-sterile recipient barley is possible with very low frequency up to 50 meters from the donor area. However, the frequency dramatically decreases with distance and due to self-pollination the possibility of cross-fertilization remains very low in normal cultivated barley.     

A polymorphic microsatellite in the limit dextrinase gene of barley (Hordeum vulgare L.)

A DNA fragment containing the exons 16, 17 and intron 16 of the limit dextrinase gene was cloned using a 654 bp cDNA as probe. Intron 16 contained a simple sequence repeat (microsatellite). PCR primers were designed to amplify that microsatellite. Using these primers, the limit dextrinase gene was mapped to the short arm of chromosome 1 (7H) using 150 DH lines from the Steptoe × Morex mapping population. This gene co-segregated with the RFLP marker ABC154A. QTLs for malt extract, -amylase activity, diastatic power and fine-coarse difference previously mapped in the North American Barley Genome Mapping Project have been located in this chromosome region. Five limit dextrinase alleles were detected in 31 barley cultivars with a PIC of 0.75. Ten different alleles/genes were identified in 23 uncultivated Hordeum species or subspecies using these microsatellite primers. The primers also amplified one fragment from wheat and two from oat. This microsatellite should be useful for marker-assisted selection for malting quality.     

Leaf expansion,photosynthesis, and water relations of sunflower plants grown on compacted soil

The potentially mineralisable nitrogen extracted from 10 soils by two methods involving boiling with dilute KCl were compared with the actual uptake of soil N by spring barley in the field, as determined with the use of ¹⁵N-labelled fertiliser. Generally good correlations were found for those soils which had previously been cropped with cereals (defined in Great Britain as either N-Index zero, or low nitrogen status soils, for fertiliser recommendations), with the results obtained by the more severe of the two methods being somewhat better than by the other method. When organic matter content was also taken into account, correlations were improved. Mineral nitrogen in the soil at sowing was highly correlated with potentially mineralisable nitrogen, and with uptake, but this relationship did not hold for soil samples taken in January, well before the likely sowing date. This suggested that early measurement of soil mineral nitrogen (when decisions on cropping are normally made) was not a practicable method for determinining spring fertiliser applications, and that the measure of potentially mineralisable nitrogen appeared more promising in this regard.     

二棱啤酒大麦杂种一代及其亲本主要性状的灰色系统分析

研究采用灰色关联分析方法,对20组二棱型啤酒大麦杂种一代及其亲本的7个主要性状之间的关联系数、关联度和关联序进行了分析。结果表明：在关联度和关联序中,大麦的穗粒数、穗粒重,千粒重分别与穗长这一性状的关联度最大,关联序中穗长全排在首位;而穗粒数,穗粒重,千粒重分别与有效穗数这一性状的关联度最小,关联序中有效穗数全排在末位,为了提高单株产量应注意协调好有效穗数与穗长这一对主要矛盾明确各性状对籽粒产量所起的直接和间接作用及其相对重要性,确定主攻方向,配制各种优势组合。为大麦亲本选配提供科学依据。从而达到二棱型啤酒大麦预期的育种目标。     

Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin

AIMS: To identify the dominant micro-organisms involved in the production of gowé, a fermented beverage, and to select the most appropriate species for starter culture development. METHODS AND RESULTS: Samples of sorghum gowé produced twice at three different production sites were taken at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia anomala, Candida krusei and Candida tropicalis. CONCLUSIONS: Gowé processing is characterized by a mixed fermentation dominated by Lact. fermentum, W. confusa and Ped. acidilactici for the LAB and by K. marxianus, P. anomala and C. krusei for the yeasts. SIGNIFICANCE AND IMPACT OF THE STUDY: The diversity of the LAB and yeasts identified offers new opportunities for technology upgrading and products development in gowé production. The identified species can be used as possible starter for a controlled fermentation of gowé.     

Short communication: Brewing properties of Nigerian white and yellow malted sorghum varieties mashed with external enzymes

Both white and yellow varieties of Nigerian sorghum have good brewing properties although the white are better. Thermamyl, the industrial enzyme used by the breweries in Nigeria in mashing unmalted sorghum, influences the brewing properties of both varieties, and yields of extract are increased when a combination of malt and Thermamyl is used. The mashing of sorghum with added enzymes is therefore recommended to improve both malt and beer quality.     

Identification and molecular characterisation of hordoindolines from barley grain

Grain texture in barley is an important quality character as soft-textured cultivars have better malting quality. In wheat, texture is considered to be determined by the puroindolines, a group of basic hydrophobic proteins present on the surface of the starch granule. Hard wheats have been proposed to lack puroindoline a or to have mutant forms of puroindoline b which do not bind to the granule surface. Analysis of six barley cultivars (three soft-textured and three hard) showed that all contained proteins homologous to wheat puroindoline b, but PCR analysis failed to show any differences in amino acid sequences similar to those which have been proposed to determine textural differences in wheat. Southern blot analysis showed two hordoindoline b genes which were isolated and shown to encode proteins with 94% sequence identity. Expression of hordoindoline b mRNA occurred in the starchy endosperm and aleurone layer of the developing seed, but not in the embryo. Analysis of seven soft- and six hard-textured barley varieties showed that all contained hordoindoline a except two hard varieties (Sundance, Hart) which were subsequently shown to both lack hordoindoline a mRNA. It was therefore concluded that there is not a clear relationship between the presence of hordoindoline a and grain texture in barley.     

Studies on the patterns of nitrogen uptake and translocation to the grain of winter barley intended for malting

In five experiments carried out between 1987 and 1989, crops of winter barley were grown under a range of agronomic treatments to study the way the treatments influenced the patterns of nitrogen uptake, dry matter production, translocation of assimilates and malting quality. Rate and timing of nitrogen fertiliser had large effects. Increased and late applications invariably increased nitrogen concentration in the grain by affecting the partitioning of nitrogen between the vegetative and reproductive parts of the plant. Foliar fungal diseases also affected nitrogen partitioning, apparently by interfering with the transport of stored nitrogen to the developing grain. Seasonal influences, especially rainfall during the grain filling period, were found to have profound effects on the pattern of change in ear and grain nitrogen concentration, and hence malting quality. The ability to predict final grain nitrogen concentration from measurements made earlier in the season is not therefore likely to be feasible.