University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Computing Heritability and Selection Response From Unbalanced Plant Breeding Trials

Abstract: Heritability is often used by plant breeders and geneticists as a measure of precision of a trial or a series of trials. Its main use is for computing the response to selection. Most formulas proposed for calculating heritability implicitly assume balanced data and independent genotypic effects. Both of these assumptions are often violated in plant breeding trials. This article proposes a simulation-based approach to tackle the problem. The key idea is to directly simulate the quantity of interest, e.g., response to selection, rather than trying to approximate it using some ad hoc measure of heritability. The approach is illustrated by three examples.

Physiological adaptations to phosphorus deficiency during proteoid root development in white lupin

Abstract: Release of large amounts of citric acid from specialized root clusters (proteoid roots) of phosphorus (P)-deficient white lupin (Lupinus albus L.) is an efficient strategy for chemical mobilization of sparingly available P sources in the rhizosphere. The present study demonstrates that increased accumulation and exudation of citric acid and a concomitant release of protons were predominantly restricted to mature root clusters in the later stages of P deficiency. Inhibition of citrate exudation by exogenous application of anion-channel blockers such as ethacrynic- and anthracene-9-carboxylic acids may indicate involvement of an anion channel. Phosphorus-deficiency-induced accumulation and subsequent exudation of citric acid seem to be a consequence of both increased biosynthesis and reduced metabolization of citric acid in the proteoid root tissue, indicated by increased in-vitro activity and enzyme protein levels of phosphoenolpyruvate carboxylase (EC 4.1.1.31), and reduced activity of aconitase (EC 4.2.1.3) and root respiration. Similar to citric acid, acid phosphatase, which is secreted by roots and involved in the mobilization of the organic soil P fraction, was released predominantly from proteoid roots of P-deficient plants. Also 33Pi uptake per unit root fresh-weight was increased by approximately 50% in juvenile and mature proteoid root clusters compared to apical segments of non-proteoid roots. Kinetic studies revealed a K m of 30.7 μM for Pi uptake of non-proteoid root apices in P-sufficient plants, versus K m values of 8.5–8.6 μM for non-proteoid and juvenile proteoid roots under P-deficient conditions, suggesting the induction of a high-affinity Pi-uptake system. Obviously, P-deficiency-induced adaptations of white lupin, involved in P acquisition and mobilization of sparingly available P sources, are predominantly confined to proteoid roots, and moreover to distinct stages during proteoid root development.

Betalain stability and degradation--structural and chromatic aspects

Abstract: In recent years, food coloring with artificial colorants has been increasingly disapproved by consumers In return, application of coloring foodstuffs, among them betalain-containing fruits and vegetables, has gained importance for the food industry As commonly true for natural pigments, betalains are afflicted with inferior stability compared to synthetic dyes Especially temperature, oxygen, and light are known to exhibit detrimental effects on betalain integrity, while certain antioxidants and chelating agents may act as stabilizers Only recently, several studies expanded the knowledge on betalain degradation pathways, especially focusing on betacyanin decomposition Additionally, new findings on stability and stabilization of betalains in cactus fruit juices extended the application range of betalainic foodstuffs Focusing on betacyanins, the present review discusses betalain degradation mechanisms and provides a survey of compounds and conditions governing betalain stability in a beneficial or an unfavorable way Finally, strategies for maintaining the chromatic properties and tinctorial strength of betalain-based juices and pigment preparations as well as tools for color modulation by targeted betacyanin degradation are discussed

Robust identification of local adaptation from allele frequencies

Abstract: Comparing allele frequencies among populations that differ in environment has long been a tool for detecting loci involved in local adaptation. However, such analyses are complicated by an imperfect knowledge of population allele frequencies and neutral correlations of allele frequencies among populations due to shared population history and gene flow. Here we develop a set of methods to robustly test for unusual allele frequency patterns, and correlations between environmental variables and allele frequencies while accounting for these complications based on a Bayesian model previously implemented in the software Bayenv. Using this model, we calculate a set of `standardized allele frequencies' that allows investigators to apply tests of their choice to multiple populations, while accounting for sampling and covariance due to population history. We illustrate this first by showing that these standardized frequencies can be used to calculate powerful tests to detect non-parametric correlations with environmental variables, which are also less prone to spurious results due to outlier populations. We then demonstrate how these standardized allele frequencies can be used to construct a test to detect SNPs that deviate strongly from neutral population structure. This test is conceptually related to FST but should be more powerful as we account for population history. We also extend the model to next-generation sequencing of population pools, which is a cost-efficient way to estimate population allele frequencies, but it implies an additional level of sampling noise. The utility of these methods is demonstrated in simulations and by re-analyzing human SNP data from the HGDP populations. An implementation of our method will be available from this http URL