The NPGS-USDA core collection with 85 accessions of red clover, an important forage species, is little described. The goal of the present study was to evaluate the diversity of a set of accessions from the core collection at the morphological and molecular level in order to extract some valuable accessions for Brazilian red clover breeding programs. Twentyone morphological traits, collected in field and greenhouse in South Brazil, and seven SSR markers were used to describe 57 accessions from the U.S. core collection and one population cultivated in Southern Brazil. Variation between accessions was large for most of the 21 morphological traits. A cluster analysis based on the morphological traits revealed five distinct clusters that separated the populations according to flowering earliness, as already described, but also according to persistency, growth habit and dry matter productivity. Over seven SSR loci, the number of alleles averaged 11.1 alleles per locus. Genetic diversity measured with SSR markers was high, with a mean expected heterozygosity of 0.86. An analysis of molecular variance revealed that the largest proportion of variation (83.6%) resided at the within population level. Although the molecular markers also separated accessions into five clusters, there was no coincidence between the composition of groups found with morphological and molecular data. Use of genetic diversity in breeding programs requires to use the most promising populations, to combine positive traits such as persistency and forage yield, and probably to use within population variation to detect valuable genotypes that could be used as parents of synthetic varieties.

Enhancing the knowledge on the genetic basis of germination and heterotrophic growth at extreme temperatures is of major importance for improving crop establishment. A quantitative trait loci (QTL) analysis was carried out at sub- and supra-optimal temperatures at these early stages in the model Legume Medicago truncatula. On the basis of an ecophysiological model framework, two populations of recombinant inbred lines were chosen for the contrasting behaviours of parental lines: LR5 at sub-optimal temperatures (5 or 10°C) and LR4 at a supra-optimal temperature (20°C). Seed masses were measured in all lines. For LR5, germination rates and hypocotyl growth were measured by hand, whereas for LR4, imbibition and germination rates as well as early embryonic axis growth were measured using an automated image capture and analysis device. QTLs were found for all traits. The phenotyping framework we defined for measuring variables, distinguished stages and enabled identification of distinct QTLs for seed mass (chromosomes 1, 5, 7 and 8), imbibition (chromosome 4), germination (chromosomes 3, 5, 7 and 8) and heterotrophic growth (chromosomes 1, 2, 3 and 8). The three QTL identified for hypocotyl length at sub-optimal temperature explained the largest part of the phenotypic variation (60% together). One digenic interaction was found for hypocotyl width at sub-optimal temperature and the loci involved were linked to additive QTLs for hypocotyl elongation at low temperature. Together with working on a model plant, this approach facilitated the identification of genes specific to each stage that could provide reliable markers for assisting selection and improving crop establishment. With this aim in view, an initial set of putative candidate genes was identified in the light of the role of abscissic acid/gibberellin balance in regulating germination at high temperatures (e.g. ABI4, ABI5), the molecular cascade in response to cold stress (e.g. CBF1, ICE1) and hypotheses on changes in cell elongation (e.g. GASA1, AtEXPA11) with changes in temperatures based on studies at the whole plant scale.

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The BCR/ABL junctional region and the b3 exon from chronic myeloid leukaemia (CML) patients were sequenced. In all 21 samples analysed the junctional region, as well as the b3 exon of 8 b3a2 mRNA molecules, presented no differences to the already described sequences. However, we identified a polymorphic base in the b2 exon in two out of seven b3a2 samples, four out of 10 b2a2 samples and all four b3a2/b2a2 samples analysed. In the eighth position before the junctional region of BCR/ABL cDNA, a cytosine replaces thymine in these cases. The polymorphism described here could be a useful marker for the differentiation of normal and rearranged BCR alleles in heterozygotes.

RESUMO -Bromus auleticus é uma espécie perene, nativa do estado do Rio Grande do Sul, que tem demonstrado adaptabilidade, potencial para produção de forragem de qualidade e alta diversidade morfológica. Neste trabalho, foram analisados padrões de bandas de sistemas enzimáticos e de marcadores RAPD, com o objetivo de determinar a variabilidade genética em 16 acessos de Bromus auleticus do Rio Grande do Sul. A variabilidade foi avaliada pelo índice de similaridade de Jaccard, utilizando-se o método UPGMA nas análises de agrupamento. Os índices de similaridade variaram de 0,0 a 0, 50 com base em isoenzimas e de 0,15 a 0,71 com base em marcadores RAPD. Os dados foram eficientes para a formação de grupos, indicando a variabilidade genética dos acessos analisados. Entretanto, houve baixa relação entre os agrupamentos e os locais de coleta. A variabilidade genética dos acessos é importante sob o ponto de vista do melhoramento genético, permitindo a seleção futura dos genótipos a partir de seus respectivos desempenhos. A utilização simultânea de isoenzimas e RAPD foi eficiente na caracterização da diversidade genética dos acessos analisados.Palavras-chave: Bromus auleticus, isoenzimas, RAPD, variabilidade genética, forrageiras nativas Genetic Variability in Natural Populations of Bromus auleticus Trin. ex Nees (Poaceae) Using Isozymes and RAPD MarkersABSTRACT -Bromus auleticus is a perennial, native species of the state of Rio Grande do Sul, which has demonstrated adaptability, potential yield of good quality forage as well as high morphological diversity. This work has analyzed band patterns from enzymatic systems and RAPD markers, with the objective to access the genetic variability in 16 accessions of Bromus auleticus from Rio Grande do Sul. The variability was evaluated using Jaccard similarity index. The method of grouping based on the average (UPGMA) was used in cluster analyses. The similarity index ranged from 0.0 to 0.50 using isozumes and from 0.15 to 0.71 using RAPD markers. The data have been efficient for the formation of different groups, indicating the genetic variability of the accession analyzed. However, these groupings have little relationship with the respective collecting places. The genetic variability of the accessions is important to the genetic improvement, allowing future genotype selection based on their respective performances. The simultaneous utilization of isozymes and RAPD was efficient in characterizing the genetic diversity of the accessions evaluated.