Diurnal rhythm of release of phytosiderophores and uptake rate of zinc in iron-deficient wheat

Abstract

The diurnal rhythm of release of phytosiderophores and uptake rate of zinc (Zn) was studied in iron (Fe) deficient wheat (Triticum aestivum L. cv. Ares) plants grown in nutrient solution under controlled environmental conditions. Different forms of Zn (e.g. ZnSO₄, ZnEDTA) were used to obtain different degrees of loading of the root apoplasmic pool with Zn.

In the Fe-deficient plants the release of phytosiderophores from the roots followed a distinct diurnal rhythm with a steep peak about 4 h after the onset of the light period. These plants also showed a similar pattern in the rates of Zn uptake over the 24 h day-night cycle. During the light period there was a steep transient peak (factor 3.8) in Zn uptake rate in the Fe-deficient plants supplied with ZnSO₄. This transient peak was much less distinct in plants supplied with ZnEDTA (factor 1.8) and absent in plants supplied with ZnEDTA plus free chelator (+ NaEDTA) in excess. The peak in Zn uptake coincided with the maximum rate of phytosiderophore release in the Fe-deficient plants. In the Fe-sufficient plants the release of phytosiderophores was very low and no such peak in Zn uptake rates could be observed.

These results demonstrate that phytosiderophores mobilize Zn not only in the rhizosphere, but also from the root apoplast. Thus, the apoplasmic pool of micronutrient cations has to be taken into account as potential source for both uptake and diurnal variation in uptake rates of Micronutrient cations.     

Genomic prediction of sunflower hybrid performance

Predicting single‐cross performance is of high importance to improve the efficiency of sunflower (Helianthus annuus L.) hybrid breeding programmes. We used experimental data from inter‐ and intragroup sunflower hybrids and their parental lines adapted to Central Europe to (i) study the genetic diversity and combining ability and (ii) examine the accuracy to predict hybrid performance based on phenotypic and genomic data. We evaluated 133 intragroup and 104 intergroup hybrids with their parental lines in replicated trials at four environments for grain yield, oil yield and oil content. Furthermore, the parental lines were fingerprinted with 572 AFLP markers. Variance due to specific combining ability was comparable for intergroup and intragroup crosses. This suggested a lack of clearly defined heterotic groups for the sample of studied sunflower lines. Prediction accuracy of hybrid performance based on general combining ability effects was high and could not be increased using genomic selection approaches. For situations where no information on GCA effects of parental lines was available, hybrid prediction based on genomic selection methods was accurate for groups of related lines. For groups of unrelated lines, however, we observed a strong decrease in the prediction accuracy. This suggests that prediction of hybrid performance for crosses based on genetically distant parents remains challenging.     

Efficient application of in vitro anther culture for different European winter wheat (Triticum aestivum L.) breeding programmes

The efficiency of our anther culture protocol was tested with high‐ and low‐responding genotypes, ‘Svilena’ and ‘Berengar’, and 93 F₁ winter wheat crosses in 2010 and 2011. Based on data for these genotypes, the effect of genotype influenced the number of embryo‐like structures, regenerated plantlets and green plantlets, while the number of albino plantlets was affected by genotype, year and environmental factors. Although genotype also influenced the production of green plantlets from breeding crosses, with green plantlets per 100 anthers ranging from 0.04 to 28.67, the average regeneration rate over all crosses was 5.3 green plantlets/100 anthers, which resulted in a total of 11 416 well‐rooted green plantlets. The survival rate of green plantlets following acclimatization was 97.21% in 2010 and 96.34% in 2011. In this study, the phenomenon of albinism and genotype dependency did not hinder the production of more than five thousand green plantlets each year. In our experiments, anther culture proved to be an efficient method in winter wheat breeding programmes with lower costs than alternative technologies.     

Administration of poly[di(sodium carboxylatoethylphenoxy)]phosphazene (PCEP) as adjuvant activated mixed Th1/Th2 immune responses in pigs

The selection of an optimal adjuvant to enhance the potency and longevity of antigen specific immune responses has always been imperative for the development of more effective and safer vaccines. A balanced type of immune enhancing ability of a new adjuvant known as polyphosphazene (PCEP) has been demonstrated in mice. In the present study we have compared the humoral and cellular immune responses to vaccine formulations containing Actinobacillus pleuropneumoniae outer membrane antigen (OmlA) with PCEP or Emulsigen as adjuvants. Our data showed a significant improvement and a shift toward more balanced immune responses when OmlA antigen was formulated with PCEP and CpG ODN. Moreover, in contrast to Emulsigen, immunization with PCEP did not result in local injection site reactions highlighting its potential as a safe and effective adjuvant for pigs. Further, the ease of formulation, administration and relatively low per dose cost of PCEP make it a promising adjuvant for pigs.     

Farmers and researchers: How can collaborative advantages be created in participatory research and technology development?

This article examines differences in the research approaches of farmers and scientists and analyzes how these differences are related to the conditions under which both groups engage in experimental work. Theoretical considerations as well as practical experiences are presented to emphasize the great potential of farmer–researcher collaboration for rural innovation. In the first part of the article, the innovative power of farmer research and experimentation is acknowledged by presenting examples such as crop and animal breeding, development of new production systems, farm equipment, and social innovations. Considering the respective comparative advantages of farmers and scientists, and inspired by theoretical concepts in the fields of knowledge management and innovation processes, we discuss five topics for optimizing the collaboration between farmers and scientists in the field of technological innovation: user orientation, decentralization, informal modes of experimentation, externalization of tacit knowledge, and economic considerations. A better understanding of such issues could help researchers to define their own role in the research process, acknowledge the strengths and weaknesses of their own and farmers’ research approaches, overcome communication gaps, and find creative solutions for problems that typically occur in the process of participatory technology development.     

Cesium‐137‐based erosion‐rate determination of a steep mountainous region

Data on quantification of erosion rates in alpine grasslands remain scarce but are urgently needed to estimate soil degradation. We determined soil‐erosion rates based on ¹³⁷Cs in situ measurements. The method integrates soil erosion over the last 22 y (time after the Chernobyl accident). Measured erosion rates were compared with erosion rates modeled with the Universal Soil Loss Equation (USLE). The comparison was done in order to find out if the USLE is a useful tool for erosion prediction in steep mountainous grassland systems. Three different land‐use types were investigated: hayfields, pasture with dwarf shrubs, and pasture without dwarf shrubs. Our test plots are situated in the Urseren Valley (Central Switzerland) with a mean slope steepness of 37°. Mean annual soil‐erosion rates determined with ¹³⁷Cs of the investigated sites ranged between the minimum of 4.7 t ha^–1 y^–1 for pastures with dwarf shrubs to >30 t ha^–1 y^–1 at hayfields and pastures without dwarf shrubs. The determined erosion rates are 10 to 20 times higher compared to previous measurements in alpine regions. Our measurements integrated over the last 22 y, including extreme rainfall events as well as winter processes, whereas previous studies mostly reported erosion rates based on summer time and short‐term rainfall simulation experiments. These results lead to the assumption that heavy‐rainfall events as well as erosion processes during winter time and early spring do have a considerable influence on the high erosion amounts that were measured. The latter can be confirmed by photographs of damaged plots after snowmelt. Erosion rates based on the USLE are in the same order of magnitude compared to ¹³⁷Cs‐based results for the land‐use type “pasture with dwarf shrubs”. However, erosion amounts on hayfields and pasture without dwarf shrubs are underestimated by the USLE compared to ¹³⁷Cs‐based erosion rates. We assume that the underestimation is due to winter processes that cause soil erosion on sites without dwarf shrubs that is not considered by the USLE. Dwarf shrubs may possibly prevent from damage of soil erosion through winter processes. The USLE is not able to perform well on the affected sites. Thus, a first attempt was done to create an alpine factor for the USLE based on the measured data.     

Nutrient flows and balances in intensively managed vegetable production of two West African cities

This study reports and analyzes nutrient balances in experimental vegetable production systems of the two West African cities of Tamale (Ghana) and Ouagadougou (Burkina Faso) over a two‐year period comprising thirteen and eleven crops, respectively. Nutrient‐use efficiency was also calculated. In Tamale and Ouagadougou, up to 2% (8 and 80 kg N ha^?1) of annually applied fertilizer nitrogen were leached. While biochar application or wastewater irrigation on fertilized plots did not influence N leaching in both cities, P and K leaching, as determined with ion‐absorbing resin cartridges, were reduced on biochar‐amended plots in Tamale. Annual nutrient balances amounted to +362 kg N ha^?1, +217 kg P ha^?1, and –125 kg K ha^?1 in Tamale, while Ouagadougou had balances of up to +692 kg N ha^?1, +166 kg P ha^?1, and –175 kg K ha^?1 y^?1. Under farmers' practice of fertilization, agronomic nutrient‐use efficiencies were generally higher in Tamale than in Ouagadougou, but declined in both cities during the last season. This was the result of the higher nutrient inputs in Ouagadougou compared to Tamale and relatively lower outputs. The high N and P surpluses and K deficits call for adjustments in local fertilization practices to enhance nutrient‐use efficiency and prevent risks of eutrophication.     

Genetic analysis of falling number in three bi‐parental common winter wheat populations

The objective of the present study was to analyse the genetic basis of falling number in three winter wheat populations. Samples for falling number determination for each population originated from at least three test environments that were free from the occurrence of preharvest sprouting at harvest time. Quantitative trait locus (QTL) analysis employing falling number values from single environments identified eight, five and three QTL in the populations Dream/Lynx, Bussard/W332‐84 and BAUB469511/Format, respectively. A major QTL common to all three populations and consistently detected in each environment mapped to the long arm of chromosome 7B. The QTL was located to a similar genomic region as the previously described major QTL for high‐isoelectric point α‐amylase content. The T1BL.1RS wheat‐rye translocation and the dwarfing gene Rht‐D1 segregating in Dream/Lynx and BAUB469511/Format were found to be important factors of falling number variation. In both populations, the presence of Rht‐D1b or the absence of T1BL.1RS increased falling number. The results indicate that late maturity α‐amylase, responsible for low falling numbers, has now been documented in German wheat germplasm.