Somatic Fusion for Breeding of Tetraploid Potatoes

From two tetraploid, one Transformed tetraploid, one triploid and 11 dihaploid clones of Solanum tuberosum somatic hybrids were produced by polyethylene glycol mediated somatic fusion. The inter-dihaploid clones comprised clones of agronomic value, homozygous doubled monohaploids, and in vitro selected clones resistant t0 Fusarium or Phytophthora toxins. Presumptive hybrids were enriched at the callus Stage in vitro by using differentiating media and by growth characteristics; further identification was performed by chromosome counting in vitro shoots and by isozyme analysis of in vitro plants. Final analysis was made from morphological characteristic of plant and tuber phenotypes. From 15 different combinations, 6009 plantlets have been regenerated. From five combinations, 310 reentrants were checked for hybrid nature by morphology and cytology and 88 by peroxidase and esterase isozyme analyses. Amongst these, from two combinations, a total of 17 different hybrids were confirmed by all methods. The procedures described are general enough to allow genome combination of interdihaploids resulting in tetraploids of practical breeding value.     

Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response

In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection.     

Public-health instruction necessary to supplement the veterinary professional curriculum: the DVM/MPH coordinated-degree program at Auburn University

To meet long-term needs, many veterinary colleges and schools are participating in dual-degree DVM/MPH programs. Auburn University's College of Veterinary Medicine and the School of Public Health at the University of Alabama at Birmingham have developed a coordinated-degree curriculum in which the DVM and the MPH are not necessarily awarded simultaneously. Other opportunities at Auburn include Public Health Careers Day, trips to the Centers for Disease Control and Prevention, several elective courses related to veterinary epidemiology, and online access to the Emerging and Exotic Diseases of Animals course available from the Veterinary Information Network. We have been able to increase our students' exposure to the role of the veterinarian in public health and to develop a program to augment their training in public practice.     

Aspects of fusion combining ability of dihaploidSolanum tuberosum L.: influence of the cytoplasm

Summary Creation from 4x hybrid clones from protoplast fusion of 2x clones of potato was evaluated. Besides combined nuclear genomes, composition of the cytoplasm significantly influenced the phenotypic traits of hybrid clones. To ascertain the influence of parental cytoplasm on the success of protoplast fusion and regeneration of hybrid plants, data from 74 fusion combinations of 50 dihaploid clones were analyzed. The majority of dihaploid breeding clones belonged to the cytoplasm types Wα, Tβ and Wγ. When the closely related mt types α, β and γ were used, fusion combinations had a better combining ability compared with more distantly related cytoplasms δ and ⃛. Fusions containing the same mitochondrial type (homofusions) were not superior to closely related mitochondrial types. However, homofusions of cytoplasm type Wα yielded significantly more hybrids than homofusions of type Tβ. In general, parental cytoplasm types had little impact on the fusion combining behaviour. Thus the cytoplasm type of the fusion parents is not a suitable marker for predicting the combining ability in protoplast fusion experiments.     

Quantitative trait loci mapping of forage agronomic traits in six mapping populations derived from European elite maize germplasm

Four agronomic traits were analysed including dry matter concentration (DMC) and dry matter yield (DMY) for stover, plant height (PHT) and days from planting to silking (DPS). We mapped quantitative trait loci (QTL) in three populations with doubled haploid lines (DHL), one RIL population and two testcross (TC) populations derived from crosses between two of the four populations mentioned above to elite tester lines, based on field phenotyping at multiple locations and years for each; 146–168 SSRs were used for genotyping of the four mapping populations. Significant high phenotypic and genotypic correlations were found for all traits at two locations, while DMC was negatively correlated with the other traits. A total of 42, 41, 54, and 45 QTL were identified for DMC, DMY, PHT, and DPS, respectively, with 9, 7, 12, and 7 major QTL for each trait. Most detected QTL displayed significant interactions with environment. Major QTL detected in more than two populations will contribute to marker‐assisted breeding and also to fine mapping candidate genes associated with maize agronomic traits.     

Molecular analysis of genetic variation in potato (Solarium tuberosum L.). II. International cultivar spectrum

Summary Seventy-five commercial potato cultivars orginating from North America, Europe and Japan were analysed using AFLP and SSR markers to assess their genetic relationships. Results of cluster and principal coordinate analysis reflect in most cases known pedigree information. Independent of the marker system used it was possible to identify groups based on their geographical descent. Cultivars from Central and East Europe formed two overlapping pools. An Anglo-American gene pool was also identified. Additionally, principal coordinate analysis based on AFLP data uncovered that this pool is subdivided in two groups. One group is more closely related to the European pools and dominated by cultivars with immediate background of cv. Kathadin. Japanese cultivars gave no distinct cluster.