Irfan Gunduz

AUGUSTUS is a software tool for gene prediction in eukaryotes based on a Generalized Hidden Markov Model, a probabilistic model of a sequence and its gene structure. Like most existing gene finders, the first version of AUGUSTUS returned one transcript per predicted gene and ignored the phenomenon of alternative splicing. Herein, we present a WWW server for an extended version of AUGUSTUS that is able to predict multiple splice variants. To our knowledge, this is the first ab initio gene finder that can predict multiple transcripts. In addition, we offer a motif searching facility, where user-defined regular expressions can be searched against putative proteins encoded by the predicted genes. The AUGUSTUS web interface and the downloadable open-source stand-alone program are freely available from http://augustus.gobics.de.

Tobacco (Nicotiana tabacum L.) is a species in the large family of the Solanaceae and is important as an agronomic crop and as a model system in plant biotechnology. Despite its importance, only limited molecular marker resources are available that can be used for genome analysis, genetic mapping and breeding. We report here on the development and characterization of 5,119 new and functional microsatellite markers and on the generation of a high-resolution genetic map for the tetraploid tobacco genome. The genetic map was generated using an F2 mapping population derived from the intervarietal cross of Hicks Broadleaf × Red Russian and merges the polymorphic markers from this new set with those from a smaller set previously used to produce a lower density map. The genetic map described here contains 2,317 microsatellite markers and 2,363 loci, resulting in an average distance between mapped microsatellite markers which is less than 2 million base pairs or 1.5 cM. With this new and expanded marker resource, a sufficient number of markers are now available for multiple applications ranging from tobacco breeding to comparative genome analysis. The genetic map of tobacco is now comparable in marker density and resolution with the best characterized genomes of the Solanaceae: tomato and potato.

Soybean mosaic virus (SMV) causes a disease of soybean [ Glycine max (L.) Merr.] that is prevalent throughout the United States. The disease can be effectively managed through the deployment of single‐dominant resistance genes known as Rsv genes that confer resistance to different strains of SMV. Pyramiding respective Rsv genes from different loci ( Rsv1, Rsv3 , and Rsv4 ) through marker‐assisted selection (MAS) is an ideal method for creating durable and wide spectrum resistance to all strains of SMV. In this study, simple sequence repeat markers were used to create isogenic lines of the susceptible cultivar Essex containing one, two, or three Rsv loci for observing background and epistatic effects of Rsv1, Rsv3 , and Rsv4 on inoculation with six strains of SMV. Results indicate that an Essex background or modifier genes from the donor source had effects on reactions of Rsv3 and Rsv4 genes, causing the isogenic lines to be more susceptible than the Rsv donor parents. Two‐gene and three‐gene isolines of Rsv1Rsv3, Rsv1Rsv4 and Rsv1Rsv3Rsv4 , acted in a complementary manner, conferring resistance against all strains of SMV, whereas isolines of Rsv3Rsv4 displayed a late susceptible reaction to selected SMV strains. We demonstrate with MAS and three near‐isogenic lines, each containing a different SMV‐resistance gene, that pyramided lines can be generated in a straightforward manner into two‐ or three‐gene–containing lines with high levels of resistance to SMV.

Soybean mosaic virus (SMV) is a major viral pathogen, affecting soybean [Glycine max (L.) Merr.] production worldwide. The Rsv3 gene of soybean confers resistance to three of the most virulent strains (G5-G7) of SMV. The objectives of this study were to map Rsv3 and develop polymerase chain reaction (PCR) based markers for marker-assisted selection (MAS) purposes. Disease-response data were collected from two F(2) mapping populations, L29 (Rsv3) x Lee68 (rsv3) and Tousan 140 (Rsv3) x Lee68 (rsv3). Bulk segregant analysis based on amplified fragment length polymorphism (AFLP) markers demonstrated that the Rsv3 locus maps to the soybean molecular linkage group (MLG) B2 between restriction fragment length polymorphism (RFLP) markers A519 and Mng247. These two tightly linked RFLP markers were converted to PCR-based markers to expedite MAS. Sequence analysis of the Mng247 genomic region revealed similarity to the consensus sequence of a leucine-rich repeat (LRR) characteristic of the extracellular LRR class of disease resistance genes. Results from this study will be useful in pyramiding viral resistance genes and in cloning the Rsv3 gene.