Swedish University of Agricultural Sciences

About: Swedish University of Agricultural Sciences is a education organization based out in Uppsala, Sweden. It is known for research contribution in the topics: Population & Soil water. The organization has 13510 authors who have published 35241 publications receiving 1414458 citations. The organization is also known as: Sveriges Lantbruksuniversitet & SLU.

Theory for growth of plants derived from the nitrogen productivity concept

Abstract: A theory is developed on the assumption that growth of plants is determined by the current amount of nitrogen in the plants. The nitrogen-growth relation is formalized in the nitrogen productivity concept (amount of biomass produced per amount of nitrogen in the biomass and per unit of time), which is essentially a constant for a given species under fixed environmental conditions. A number of results follow for increases in whole plant biomass: (A) The relative growth rate is a linear function of the internal nitrogen concentration. (B) The maximal relative growth rate uniquely determines the scaling of the time axis. (C) Exponential growth is consistent only with stable internal nitrogen concentration. Dose-response curves expressed in reduced variables (the ratio between a variable and the same variable for a plant growing under optimal conditions) are universal, so that all species and all environmental conditions yield the same curve. This is confirmed by experimental data. The shape (linear, exponential, etc.) of the nitrogen uptake curve is the only parameter differentiating these universal curves. The Mitscherlich curve or variations of it can be fitted very closely to the derived dose-response curves, except under exponential growth. A conclusion drawn from the analysis is that the results of nutrition experiments cannot be properly interpreted unless the variation with time of the amount of nitrogen in the plant is known. The theory can be extended to more complex situations, for example, time-varying environmental conditions.

Genome editing in potato via CRISPR-Cas9 ribonucleoprotein delivery

Abstract: Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein-9 (CRISPR-Cas9) can be used as an efficient tool for genome editing in potato (Solanum tuberosum). From both a scientific and a regulatory perspective, it is beneficial if integration of DNA in the potato genome is avoided. We have implemented a DNA-free genome editing method, using delivery of CRISPR-Cas9 ribonucleoproteins (RNPs) to potato protoplasts, by targeting the gene encoding a granule bound starch synthase (GBSS, EC 2.4.1.242). The RNP method was directly implemented using previously developed protoplast isolation, transfection and regeneration protocols without further adjustments. Cas9 protein was preassembled with RNA produced either synthetically or by in vitro transcription. RNP with synthetically produced RNA (cr-RNP) induced mutations, i.e. indels, at a frequency of up to 9%, with all mutated lines being transgene-free. A mutagenesis frequency of 25% of all regenerated shoots was found when using RNP with in vitro transcriptionally produced RNA (IVT-RNP). However, more than 80% of the shoots with confirmed mutations had unintended inserts in the cut site, which was in the same range as when using DNA delivery. The inserts originated both from DNA template remnants from the in vitro transcription, and from chromosomal potato DNA. In 2-3% of the regenerated shoots from the RNP-experiments, mutations were induced in all four alleles resulting in a complete knockout of the GBSS enzyme function.

Members' perception of their participation in the governance of cooperatives: the key to trust and commitment in agricultural cooperatives.

Abstract: This study explores to which extent the members’ assessment of their cooperatives’ degree of success are related to various member attributes, with special reference to the members’ perception of their participation in the governance of the cooperatives. Three categories of member attributes are identified: Satisfaction with the profitability of farm operations, Age, and Experience from board work. The cooperatives’ degree of success is measured as members’ commitment towards cooperatives, and members’ trust in the board of directors. The data originates from a mail survey among Swedish farmers. A total of 2,250 farmers received a questionnaire. The response rate was 52%. The results indicate differences in members’ cooperative commitment and their trust towards directors to be due to farm operations profitability, age and experience as directors. After adding members’ perception of their participation in the governance as a covariate, most of the other differences are explained by this variable. Age is still to some extent associated with trust towards directors, as older farmers have less trust in directors.

Inter‐ and intraspecific variation in the ITS region of rDNA of ectomycorrhizal fungi in Fennoscandia as detected by endonuclease analysis

Abstract: Interspecific and intraspecific variation in the internal transcribed spacer (ITS) region of rDNA of ectomycorrhizal fungi of 44 species in 17 genera were examined using the restriction fragment length polymorphism (RFLP) method. For each species, two to five herbarium vouchers (mainly basidiocarps), collected throughout Fennoscandia, were examined. The ITS region was amplified using the polymerase chain reaction (PCR) and the universal primers ITS1 and ITS4, and subjected to RFLP analysis with three endonucleases. Intraspecific polymorphisms in the ITS region were found in seven species (in nine of the 132 herbarium vouchers). Polymorphisms were due to length mutations, ranging from 5 to 15 bp in four of the seven polymorphic species and mutations in endonuclease restriction sites in six species, mostly affecting only one endonuclease, but in two species two endonucleases. Using a single endonuclease, a unique RFLP pattern could be obtained for more than half the investigated species. By combining different endonucleases, 34 (77%) of the species could be distinguished from another. The remaining RFLP types occurred in one genus. On the basis of the low intra- but high interspecific variation in the ITS region, it is concluded that most ectomycorrhizas formed by the 44 investigated species should be recognized by comparison with this dataset, if the mycorrhizas are sampled from a site located in Fennoscandia. However, in datasets from even larger geographical areas encompassing a higher degree of intraspecific variation in the ITS region, or when mycorrhizas from several sites distant from each other are compared, it might be necessary to include local reference species.