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.

Genotypic variation in cold tolerance influences the yield of Miscanthus

Abstract: Farrell, A. D., Clifton-Brown, J. C., Lewandowski, I., Jones, M. B. (2006). Genotypic variation in cold tolerance influences the yield of Miscanthus. Annals of Applied Biology, 149, (3), 337-345.

The immediate cause of the diurnal changes of nitrogen metabolism in leaves of nitrate‐replete tobacco: a major imbalance between the rate of nitrate reduction and the rates of nitrate uptake and ammonium metabolism during the first part of the light period

Abstract: To assess how diurnal changes of nitrate reductase (NIA) expression in leaves interact with upstream and downstream processes during nitrate utilization, nitrate uptake, and nitrate and ammonium metabolism were investigated at several times during the diurnal cycle in wild-type tobacco. Plants were grown hydroponically on 2 mM nitrate to exclude possible complications due to changes in the external availability of nitrate, and to allow nitrate uptake to be measured in the growth conditions. (a) In leaves, the NIA transcript decreases during the day and recovers at night, and NIA activity increases three-fold during the first part and declines during the second part of the light period. Nitrate decreases during the day and recovers at night, ammonium, glutamine, glycine and serine increase during the day and decrease at night, and 2-oxoglutarate increases three-fold after illumination and decreases during the last part of the light period. The amplitudes of the diurnal changes are similar to or larger than in tobacco grown on high nitrate in sand. The transcript for plastid glutamine synthetase (GLN2) is low at the end of the night and increases during the day, and glutamine synthetase activity increases to a peak at the end of the day and decreases at night. (b) In the roots, transcript levels for the high affinity nitrate transporter (NRT2) increase in the day and decrease at night. Nitrate uptake is about 40% higher during the day than at night. (c) Comparison of the diurnal changes of the leaf metabolite pools with the rate of nitrate uptake allows diurnal changes in fluxes to be estimated. During the first part of the light, the rate of nitrate assimilation is about two-fold higher than the rate of nitrate uptake, and also exceeds the rate at which reduced nitrogen is metabolized in the GOGAT pathway. The resulting decrease of leaf nitrate and accumulation of nitrogen in intermediates of ammonium metabolism and photorespiration represent about 40 and 15%, respectively, of the total nitrate that enters the plant in 24 h. Later in the diurnal cycle as NIA expression and activity decline, this imbalance is reversed. NRT2 expression and nitrate uptake remain relatively high, and nitrate taken up during the night is used to replenish the leaf nitrate pool. Increased GLN2 expression in leaves during the second part of the light period allows continued assimilation of ammonium released during photorespiration and remobilization of the reduced nitrogen that accumulated earlier in the diurnal cycle.

Genomic regions influencing resistance to the parasitic weed Striga hermonthica in two recombinant inbred populations of sorghum

Abstract: Molecular markers for resistance of sorghum to the hemi-parasitic weed Striga hermonthica were mapped in two recombinant inbred populations (RIP-1, -2) of F3:5 lines developed from the crosses IS9830 × E36-1 (1) and N13 × E36-1 (2). The resistant parental lines were IS9830 and N13; the former is characterized by a low stimulation of striga seed germination, the latter by “mechanical” resistance. The genetic maps of RIP-1 and RIP-2 spanned 1,498 cM and 1,599 cM, respectively, with 137 and 157 markers distributed over 11 linkage groups. To evaluate striga resistance, we divided each RIP into set 1 (116 lines tested in 1997) and set 2 (110 lines evaluated in 1998). Field trials were conducted in five environments per year in Mali and Kenya. Heritability estimates for area under the striga number progress curve (ASNPC) in sets 1 and 2 were respectively 0.66 and 0.74 in RIP-1 and 0.81 and 0.82 in RIP-2. Across sites, composite interval mapping detected 11 QTL (quantitative trait loci) and nine QTL in sets 1 and 2 of RIP-1, explaining 77% and 80% of the genetic variance for ASNPC, respectively. The most significant RIP-1 QTL corresponded to the major-gene locus lgs (low stimulation of striga seed germination) in linkage group I. In RIP-2, 11 QTL and nine QTL explained 79% and 82% of the genetic variance for ASNPC in sets 1 and 2, respectively. Five QTL were common to both sets of each RIP, with the resistance alleles deriving from IS9830 or N13. Since their effects were validated across environments, years and independent RIP samples, these QTL are excellent candidates for marker-assisted selection.

Genome-wide linkage and QTL mapping in porcine F2 families generated from Pietrain, Meishan and Wild Boar crosses

Abstract: Summary Three informative pig F2 families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome-wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F2 phenotypic variance could be identified at p < 0.05 chromosome-wide level. Differences in the numbers and positions of QTLs were observed between families. Genome-wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body-conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1-A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073-NGFB). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2-S0102) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome-wide QTL mapping in F2 families represents an essential starting point and is therefore significant for animal breeding. Zusammenfassung Drei informative F2-Familien, die aus Kreuzungen von Europaischem Wildschwein (W), Meishan (M) und Pietrain (P) erstellt worden waren, wurden fur eine genomweite Kopplungs- und QTL-Analyse benutzt. Insgesamt wurden 129 Mikrosatellitenloci, 56 Type-I-Loci und 46 Merkmalsdefinitionen (fur Wachstum, Mastleistung, Fettansatz, Bemuskelung, Fleischqualitat, Stressresistenz und Korperform) in die Untersuchungen einbezogen. In den Kopplungskarten der Familien M × P, W × P und W × M wurden durchschnittliche Markerabstande von 18.4, 19.7 bzw. 18.8 cM erreicht und 582, 534 bzw. 625 informative Meiosen beobachtet. Fur die Gesamtlangen der Autosomen wurden in den drei Familien 27.3, 26.0 bzw. 26.2 Morgan-Einheiten gemessen. Die maternalen Kopplungskarten waren durchschnittlich 1.3-fach langer als die paternalen. QTLs, die mehr als 3% der phanotypischen Varianz in der F2-Generation erklarten, konnten mit p < 0.05 chromosomenweitem Signifikanzniveau nachgewiesen werden. Zwischen den Familien wurden Differenzen in den Anzahlen und Positionen der QTLs beobachtet. Genomweit signifikante QTL-Effekte wurden fur Wachstum und Fettansatz auf acht Chromosomen (1, 2, 4, 13, 14, 17, 18 und X) kartiert, fur Fettansatz auf sieben Chromosomen (1, 2, 3, 4, 6, 7 und X), fur Bemuskelung auf elf Chromosomen (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 und X), fur Fleischqualitat/Stressresistenz auf sieben Chromosomen (2, 3, 6, 13, 16, 18 und X), und QTLs fur die Korperform wurden auf 14 Chromosomen kartiert. Eng korrelierte Merkmale zeigten ahnliche QTL-Profile innerhalb Familien. Die bedeutsamsten QTL-Effekte wurden fur Fleischqualitats- und Stressresistenzmerkmale auf Chromosom 6, Intervall RYR1-A1BG, in den Familien W × P und M × P gefunden, wahrend in diesem Chromosomenintervall in der Familie W × M, in der der RYR1-Locus keine segregierenden Exon-Allele aufwies, kein QTL zu erkennen war. Mehrere der QTL-Positionen waren fur die Korperform wie auch fur Wachstum, Mastleistung, Fettansatz und Bemuskelung in zwei von drei Familien ahnlich. Dies galt besonders fur Chromosom 4 (Intervall SW1073-NGFB). QTLs mit grosen Effekten wurden auf Chromosom 7 im MHC (Intervall CYP21A2-S0102) kartiert; sie beeinflussten Korperlange, Kopfgewicht, aber auch viele weitere Merkmale. Zur Identifizierung der DNA-Varianten, die einem QTL zugrunde liegen, ist eine Feinkartierung von QTLs und positionale Klonierung erforderlich. Fur diese nachfolgenden Untersuchungsmethoden ist jedoch die genomweite QTL-Kartierung in F2-Familien ein entscheidender Ausgangspunkt; sie ist deshalb bedeutungsvoll fur die Tierzuchtung.

Crystal structure of 12-oxophytodienoate reductase 3 from tomato: Self-inhibition by dimerization

Abstract: 12-Oxophytodienoate reductase (OPR) 3, a homologue of old yellow enzyme (OYE), catalyzes the reduction of 9S,13S-12-oxophytodienoate to the corresponding cyclopentanone, which is subsequently converted to the plant hormone jasmonic acid (JA). JA and JA derivatives, as well as 12-oxophytodienoate and related cyclopentenones, are known to regulate gene expression in plant development and defense. Together with other oxygenated fatty acid derivatives, they form the oxylipin signature in plants, which resembles the pool of prostaglandins in animals. Here, we report the crystal structure of OPR3 from tomato and of two OPR3 mutants. Although the catalytic residues of OPR3 and related OYEs are highly conserved, several characteristic differences can be discerned in the substrate-binding regions, explaining the remarkable substrate stereoselectivity of OPR isozymes. Interestingly, OPR3 crystallized as an extraordinary self-inhibited dimer. Mutagenesis studies and biochemical analysis confirmed a weak dimerization of OPR3 in vitro, which correlated with a loss of enzymatic activity. Based on structural data of OPR3, a putative mechanism for a strong and reversible dimerization of OPR3 in vivo that involves phosphorylation of OPR3 is suggested. This mechanism could contribute to the shaping of the oxylipin signature, which is critical for fine-tuning gene expression in plants.