Items from Germany.

ITEMS FROM GERMANY

 

INSTITUT FÜR PFLANZENGENETIK UND KULTURPFLANZENFORSCHUNG (IPK)

Corrensstraße 3, 06466 Gatersleben, Germany.

 

Genetic integrity of wheat germ plasm preserved in the Gatersleben genebank.

In gene banks worldwide, about six million accessions of cultivated crops are conserved, including about 750,000 wheats. One of the main challenges for gene banks is maintenance of the genetic integrity of accessions. The contamination by foreign pollen or incorrect handling during multiplication may affect the genetic identity of the material. Molecular methods assessing genetic variation at the DNA level will be useful to prove the purity of genebank accessions after long-term maintenance.

Eight wheat accessions differing in their frequency of multiplication were selected randomly out of the Gatersleben genebank wheat collection consisting of about 17,000 accessions in total. For each accession, samples of grain and complete spikes are deposited as vouchers when they are grown initially. Although the samples are stored at room temperature and, therefore, have lost their germinability, it is still possible to extract DNA for comparative studies. Living seed material originating from the most recent regeneration are stored at a temperature of 0°C.

Grain derived from the first and last regeneration cycles was used to study the genetic identity of wheat accessions regenerated up to 24 times using wheat microsatellite markers. No contamination resulting from cross pollination or erroneous handling during harvesting, threshing, or labeling was detected. For one accession (TRI 4599), genetic drift was observed, whereas for TRI 249, a heterogenous situation for two markers was maintained over the years. We concluded that microsatellites can be used as a simple and reliable marker system for the verification of the integrity and genetic stability of genebank accessions.

 

Mapping a wheat GA insensitive Rht gene homoeologue in barley.

Wheat breeding programs worldwide successfully have exploited the GA-insensitive dwarfing genes Rht1 (Rht-B1b) and Rht2 (Rht-D1b). The corresponding loci Rht-B1 and Rht-D1, which are located on chromosomes 4BS and 4DS, respectively, were mapped recently using RFLP markers (Börner et al. 1997, Theor Appl Genet 95:1133-1137). As a result of somaclonal variation, a mutant showing no response to GA was detected in barley (Falk 1994, Barley Genet Newslet 24:87-89). This mutant, which carries a dominant GA-insensitive dwarfing gene (Dwf2), was of extremely short stature and resembled wheat plants that have the very potent dwarfing genes/alleles Rht3 (Rht-B1c) or Rht10 (Rht-D1c), which are on chromosomes 4BS and 4DS, respectively. Using RFLP and microsatellite markers, Dwf2 was mapped on the short arm of barley chromosome 4H at a position homoeologous to the multiallelic Rht-B1 and Rht-D1 loci. The colinearity of the molecular markers confirms the hypothesis that a homoeoallelic relationship exists between the GA-insensitive dwarfing genes of wheat and barley.

 

Publications.

  • Börner A and Koran V. 2000. Major gene and QTL mapping in rye (Secale cereale L.). In: Proc Internat Triticeae Mapping Initiative Public Workshop, Viterbo, Italy, 24-28 August 1999 (In press).
  • Börner A, Chebotar S, and Korzun V. 2000. Molecular characterization of the genetic integrity of wheat (Triticum aestivum L.) germplasm after long term maintenance. Theor Appl Genet (In press).
  • Börner A, Unger O, and Meinel A. 1999. Genetics of durable adult plant resistance to rust diseases in wheat (Triticum aestivum L.). In: Genetics and Breeding for Crop Quality and Resistance (Scarascia-Mugnozza GT, Porceddu E, and Pagnotta MA eds). Pp. 61-66.
  • Börner A, Röder MS, Unger O, and Meinel A. 2000. The detection and molecular mapping of a major gene for non specific adult plant disease resistance against stripe rust (Puccinia striiformis) in wheat. Theor Appl Genet (In press).
  • Börner A, Korzun V, Voylokov AV, and Weber WE. 1999. Detection of quantitative trait loci on chromosome 5R of rye (Secale cereale L.). Theor Appl Genet 98:1087-1090.
  • Börner A, Korzun V, Malyshev S, Ivandic V, and Graner A. 1999. Molecular mapping of two dwarfing genes differing in their GA response on chromosome 2H of barley. Theor Appl Genet 99:670-675.
  • Ivandic V, Malyshev S, Korzun V, Graner A, and Börner A. 1999. Comparative mapping of a gibberellic acid insensitive dwarfing gene (Dwf2) on chromosome 4HS in barley. Theor Appl Genet 98:728-731.
  • Korzun V, Malyshev S, Pickering RA, and Börner A. 1999. RFLP mapping of a gene for hairy leaf sheath using a recombinant line from Hordeum vulgare L. x Hordeum bulbosum L. cross. Genome 42:960-963.
  • Korzun, V, Börner A, Siebert R, Malyshev S, Hilpert M, Kunze R, and Puchta H. 1999. Chromosomal location and genetic mapping of the mismatch repair gene homologs MSH2, MSH3 and MSH6 in rye and wheat. Genome 42:1255-1257.
  • Pestsova E, Salina E, Börner A, Korzun V, Maystrenko OI, and Röder MS. 2000. Microsatellites support the authenticity of inter-varietal chromosome substitution lines of wheat (Triticum aestivum L.). Theor Appl Genet (In press).
  • Salina E, Börner A, Leonova I, Korzun V, Laikova L, Maystrenko O, and Röder MS. 2000. Comparative microsatellite mapping of the induced sphaerococcoid mutation genes in Triticum aestivum. Theor Appl Genet (In press).
  • Specht C-E and Börner A. 2000. Comparative study on seed germination of selected species of the Gatersleben genebank testing the effect of freezing and defrosting on their germinability. Plant Genet Resour Newslet (In press).