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.

Two high-density AFLP linkage maps of Zea mays L.: analysis of distribution of AFLP markers.

Abstract: This study demonstrates the relative ease of generating high-density linkage maps using the AFLP® technology. Two high-density AFLP linkage maps of Zea mays L. were generated based on: (1) a B73 × Mo17 recombinant inbred population and (2) a D32 × D145 immortalized F2 population. Although AFLP technology is in essence a mono-allelic marker system, markers can be scored quantitatively and used to deduce zygosity. AFLP markers were generated using the enzyme combinations EcoRI/MseI and PstI/MseI. A total of 1539 and 1355 AFLP markers have been mapped in the two populations, respectively. Among the mapped PstI/MseIAFLP markers we have included fragments bounded by a methylated PstI site (mAFLP markers). Mapping these mAFLP markers shows that the presence of C-methylation segregates in perfect accordance with the primary target sequence, leading to Mendelian inheritance. Simultaneous mapping of PstI/MseIAFLP and PstI/MseI mAFLP markers allowed us to identify a number of epi-alleles, showing allelic variation in the CpNpG methylation only. However, their frequency in maize is low. Map comparison shows that, despite some rearrangements, most of the AFLP markers that are common in both populations, map at similar positions. This would indicate that AFLP markers are predominantly single-locus markers. Changes in map order occur mainly in marker-dense regions. These marker-dense regions, representing clusters of mainly EcoRI/MseI AFLP and PstI/MseI mAFLP markers, co- localize well with the putative centromeric regions of the maize chromosomes. In contrast, PstI/MseImarkers are more uniformly distributed over the genome.

Microbial ecology of cereal fermentations

Abstract: Cereals are globally number one as food crops as well as substrates for fermentation Well known products are beer, sake, spirits, malt vinegar, and baked goods made from doughs leavened by yeasts or sourdough Fermentation processes are enabled by technological measures that act on the metabolically resting grains and direct ecological factors controlling the activity of lactic acid bacteria and yeasts Fermentable substrates originate from endogenous or added hydrolytic enzyme activities Examples of their management are malting, koji technology, addition of enzymes from external sources and sourdough, which stands on the origin of all fermentation When sourdough is continuously propagated under the conditions applied in bakery practice, a stable association of only few species of lactic acid bacteria (LAB) and yeasts achieve dominance and ensure a controlled process The variation of the ecological parameters acting on the microbial association such as the nature of cereal, temperature, size of inoculum, and length of propagation intervals leads in each case to a characteristic species association, thus explaining that altogether 46 LAB species and 13 yeast species have been identified as sourdough specific

Overview of Heterosis and Heterotic Groups in Agronomic Crops

Abstract: Heterotic groups and patterns are of fundamental importance in hybrid breeding. We start with definitions of these tenns. Theoretical and experimental arguments are given demonstrating the superiority of inter-group compared with intra-group crosses under two aspects: (i) a higher mean heterosis and hybrid perfonnance and (ii) a reduced specific combining ability (SCA) variance and lower ratio of SCA to general combining ability (GCA) variance, which implies that identification of superior hybrids can be based mainlyon testing for GCA. We review the degree of heterosis, history and current status of hybrid breeding, and development of heterotic groups in five major crops with different pollination systems: allogamous—maize (Zea mays L.) and rye (Secale cereale L.); partially allogamous—faba bean (Vicia faba L.) and oilseed rape (Brassica napus L.); autogamous— rice (Oryza sativa L.). Fundamental principles and systematic approaches for identification of heterotic groups and patterns and enlarging their genetic base are suggested with special consideration of the use of molecular markers for grouping of gennplasm. Adapted populations, isolated either by time and/or space are most suitable candidates for promising heterotic patterns. The potential of heterotic groups in clone and population breeding also is discussed.

Population structure and genetic diversity in a commercial maize breeding program assessed with SSR and SNP markers

Abstract: Information about the genetic diversity and population structure in elite breeding material is of fundamental importance for the improvement of crops. The objectives of our study were to (a) examine the population structure and the genetic diversity in elite maize germplasm based on simple sequence repeat (SSR) markers, (b) compare these results with those obtained from single nucleotide polymorphism (SNP) markers, and (c) compare the coancestry coefficient calculated from pedigree records with genetic distance estimates calculated from SSR and SNP markers. Our study was based on 1,537 elite maize inbred lines genotyped with 359 SSR and 8,244 SNP markers. The average number of alleles per locus, of group specific alleles, and the gene diversity (D) were higher for SSRs than for SNPs. Modified Roger's distance (MRD) estimates and membership probabilities of the STRUCTURE matrices were higher for SSR than for SNP markers but the germplasm organization in four heterotic pools was consistent with STRUCTURE results based on SSRs and SNPs. MRD estimates calculated for the two marker systems were highly correlated (0.87). Our results suggested that the same conclusions regarding the structure and the diversity of heterotic pools could be drawn from both markers types. Furthermore, although our results suggested that the ratio of the number of SSRs and SNPs required to obtain MRD or D estimates with similar precision is not constant across the various precision levels, we propose that between 7 and 11 times more SNPs than SSRs should be used for analyzing population structure and genetic diversity.