Genomewide association study reveals novel quantitative trait loci associated with resistance towards Septoria tritici blotch in North European winter wheat

Fungal diseases are a major constraint for wheat production. Effective disease resistance is essential for ensuring a high production quality and yield. One of the most severe fungal diseases of wheat is Septoria tritici blotch (STB), which influences wheat production across the world. In this study, genomewide association mapping was used to identify new chromosomal regions on the wheat genome conferring effective resistance towards STB. A winter wheat population of 164 North European varieties and breeding lines was genotyped with 15K single nucleotide polymorphism (SNP) wheat array. The varieties were evaluated for STB in field trials at three locations in Denmark and across 3 years. The association analysis revealed four quantitative trait loci, on chromosomes 1B, 2A, 5D and 7A, highly associated with STB resistance. By comparing varieties containing several quantitative trait loci (QTL) with varieties containing none of the found QTL, a significant difference was found in the mean disease score. This indicates that an effective resistance can be obtained by pyramiding several QTL.     

Evaluation of dog owners' perceptions concerning radiation therapy

Background

External radiation therapy (RT) has been available for small animals in Sweden since 2006. This study was designed to obtain information on owner experiences and perceptions related to RT of cancer in their dogs. Another survey was used to determine the attitudes about use of RT in a group of Swedish veterinarians. Their responses were analyzed and compared to their level of knowledge of oncology and RT.

Methods

Owners of all dogs (n = 23) who had undergone RT for malignancy at Jönköping Small Animal Hospital between March 2006 to September 2007 were interviewed. A questionnaire was given to a selected group of veterinarians.

Results

All 23 owners responded. All owners thought that their dog did well during RT and most that their dog was also fine during the following phase when acute RT-related skin reactions occur and heal. Three owners stated that their dog had pain that negatively impacted quality of life because of radiation dermatitis. Five owners reported that RT positively impacted quality of life of the dog during the first weeks after RT because palliation was achieved. The owners were not disturbed by the efforts required of them. All but one owner (22 of 23) stated that they would make the same decision about RT again if a similar situation occurred. The most important factor for this decision was the chance to delay occurrence of tumour-related discomfort. The chance for cure was of less importance but still essential, followed by expected side effects. Time commitments, travel, number of treatments required and financial cost; all had low impact. The veterinarian survey showed that less background knowledge of small animal oncology/RT was associated with more negative expectations of RT for small animals.

Conclusion

The results show that for these owners, RT was a worthwhile treatment modality and that the discomfort for the dog was manageable and acceptable relative to the benefits. Improved continuing education about small animal RT in Sweden will likely result in increased evidence-based and positive treatment recommendations concerning RT by veterinarians.     

Seaweed Hydrocolloid Production: An Update on Enzyme Assisted Extraction and Modification Technologies

Agar, alginate, and carrageenans are high-value seaweed hydrocolloids, which are used as gelation and thickening agents in different food, pharmaceutical, and biotechnological applications. The annual global production of these hydrocolloids has recently reached 100,000 tons with a gross market value just above US$ 1.1 billion. The techno-functional properties of the seaweed polysaccharides depend strictly on their unique structural make-up, notably degree and position of sulfation and presence of anhydro-bridges. Classical extraction techniques include hot alkali treatments, but recent research has shown promising results with enzymes. Current methods mainly involve use of commercially available enzyme mixtures developed for terrestrial plant material processing. Application of seaweed polysaccharide targeted enzymes allows for selective extraction at mild conditions as well as tailor-made modifications of the hydrocolloids to obtain specific functionalities. This review provides an update of the detailed structural features of κ-, ι-, λ-carrageenans, agars, and alginate, and a thorough discussion of enzyme assisted extraction and processing techniques for these hydrocolloids.     

Heat induced formation of free radicals in wheat flour

Oxidative Stability of bread is increasingly being recognized as important for long shelf-life. Formation of free radicals in whole wheat flour and white flour during heating was compared using Electron Spin Resonance spectroscopy in order to identify the primary oxidative events. Heating lead to a higher content of free radicals in wholemeal wheat flour than in white flour, since components in the husk seem to make a major contribution. Two different pathways are suggested for the formation of free radicals in wheat flour. The activation energy for the radical formation in the flours was estimated by Arrhenius plot as 34 kJ mol⁻¹ up to 453 K, and above 473 K higher activation energies were observed. The change in activation energies indicates a change in reaction mechanisms for oxidation probably involving species with different mobility, i.e. different molecular weight. The accumulated concentration of free radicals in heated flour increased during one month storage and it is slightly affected by the water activity in the storage container.     

Chromosomal regions associated with the in vitro culture response of wheat (Triticum aestivum L.) microspores

Generation of doubled haploid plants is a powerful tool in breeding, as homozygous individuals will be obtained directly from hybrids. However, genotype variability in regeneration efficiency of most European wheat (Triticum aestivum L.) varieties has limited its use in wheat. This study intended to identify quantitative trait loci (QTLs) for green plantlet regeneration from wheat microspore cultures. A QTL analysis using DArT markers was conducted based on a bi‐parental F₃ population, derived from a cross between the varieties Svilena and Jensen, which displayed markedly different capacity for plantlet regeneration. Two QTLs on chromosome 1B and 7B explained 53% of the variation in green plantlet regeneration. Furthermore, a collection of 94 European wheat varieties was genotyped and phenotyped. The microspore response level was low among western and northern European wheat varieties, and the positive QTLs found in the bi‐parental population were rare in the variety collection. Identification of the two QTLs enables introduction of high regeneration efficiency into wheat germplasm. Moreover, our results proved that the efficient regeneration observed for one variety could be crossed into modern winter wheat.     

重金属胁迫对紫叶稠李叶片解剖结构的影响

以城市绿化栽培品种紫叶稠李(Prunus padus L.)为研究对象,在6种重金属锌、铜、铅、汞、铬、镉的不同浓度胁迫条件下,观测紫叶稠李叶片解剖结构以及抗重金属特征,测定叶片厚度、上表皮厚度、下表皮厚度、栅栏组织厚度、海绵组织厚度、栅栏组织/海绵组织、角质层厚度等7个指标,并进行了综合评价。结果表明:除镉外,随着其他重金属浓度的增加,栅栏组织逐渐变厚,海绵组织逐渐变薄,而随着镉浓度的逐渐增加,栅栏组织先变厚后变薄,海绵组织逐渐分化,在不同梯度镉浓度重量处理下,角质层厚度显著增加。可见,紫叶稠李具有较强的抗重金属特征,该树种可作为重金属富集区园林绿化树种。