Interspecific or intergeneric hybridization, followed by chromosome doubling, can lead to the formation of new allopolyploid species. Recent studies indicate that allopolyploid formation is associated with genetic and epigenetic changes. Despite these studies, it is not yet clear whether the C value of an allopolyploid is the sum of its diploid parents. To address this question, six newly synthesized wheat allopolyploids and their parental plants were investigated. It was found that allopolyploids have a genome size significantly smaller than the expected value. The reduction of the nuclear genome size in the synthetic allotetraploids and allohexaploids was 2 pg DNA at 2C. It was also found that changes in the genome size already existed in the first generation amphiploids, indicating that the change was a rapid event. There was no difference in the reduction of nuclear genome size between the allotetraploid and the allohexaploid. These data clearly show that genome differentiation in allopolyploids was not related to the ploidy level. The data obtained clearly suggested that the nonadditive change in genome size that occurred during allopolyploidization may represent a preprogrammed adaptive response to genomic stress caused by hybridization and allopolyploidy, which serves to stabilize polyploid genomes.

Faba bean is cultivated worldwide and widely used in Mediterranean countries, Asia and Europe. However, only a few faba bean breeders are active in cultivar development. As a result, a limited number of varieties are available for growers. Plant genetic resources or germplasm are fundamental sources for plant breeding, and the assessment of the genetic diversity among germplasm accessions is useful to facilitate more efficient use of plant genetic resources. A mini-core collection of faba bean germplasm (178 landraces and four cultivars), from diverse geographic regions of Turkey, was assessed for agro-morphological performance and some quality traits. There were substantial variations for the investigated morphological and quality characteristics. The analysis of variance revealed that the differences among 182 accessions were significant for all the studied characters. Some accessions showed very good agronomic performance for some traits. Positive and negative correlations existed among different morphological and agronomic traits. Landraces have been classified into four different groups using a cluster analysis. These results suggest that an a priori classification of accessions according to the growing area does not strictly correspond to phenotypic grouping. From the spatial distribution of landraces, however, it has been possible to identify ‘superior’ accessions of some traits. These findings indicate a number of useful traits in the gene pools and a wide range of phenotypic variation that provides a good source of diversity for use in modern faba bean breeding programmes.

Dwarfing genes play an important role in improving yield and adaptability of wheat cultivars in most production environments. Understanding the allelic distribution at dwarfing loci is very important for any wheat-breeding programmes. In this study, we reported the allelic constitution at microsatellite locus Xgwm261 and the two major height-reducing genes Rht-B1 and Rht-D1 among a set of 56 bread wheat cultivars and nine landraces, based on diagnostic polymerase chain reaction assays. With respect to Rht-B1, 37% of the accessions carried the dwarfing allele Rht-B1b, while at Rht-D1, only one accession carried the dwarfing allele Rht-D1b. The allelic state at Rht8 was assayed indirectly by genotyping for the linked microsatellite locus Xgwm261. About 26% of the accessions carried the 192 bp allele (linked with Rht8 gene in some cases), whereas 35 and 12% genotypes carried 165 and 174 bp allele at the microsatellite locus Xgwm261. Cultivars released from 1980 onwards increasingly carried either Rht-B1b or Rht8. This information should allow for a more rational use of this collection for the purpose of wheat improvement in Turkey.