Chilling requirement (CR) for bud dormancy completion determines the time of bud break in apple (Malus × domestica Borkh.). The molecular control of bud dormancy is highly heritable, suggesting a strong genetic control of the trait. An available Infinium II SNP platform for genotyping containing 8,788 single nucleotide polymorphic markers was employed, and linkage maps were constructed in a F1 cross from the low CR M13/91 and the moderate CR cv. Fred Hough. These maps were used to identify quantitative trait loci (QTL) for bud break date as a trait related to dormancy release. A major QTL for bud break was detected at the beginning of linkage group 9 (LG9). This QTL remained stable during seven seasons in two different growing sites. To increase mapping efficiency in detecting contributing genes underlying this QTL, 182 additional SNP markers located at the locus for bud break were used. Combining linkage mapping and structural characterization of the region, the high proportion of the phenotypic variance in the trait explained by the QTL is related to the coincident positioning of Arabidopsis orthologs for ICE1, FLC, and PRE1 protein-coding genes. The proximity of these genes from the most explanatory markers of this QTL for bud break suggests potential genetic additive effects, reinforcing the hypothesis of inter-dependent mechanisms controlling dormancy induction and release in apple trees.

Elionurus muticus naturally occurs in southern Brazil and its economic potential is due to the presence of essential oils. There are few studies about this genus. Thus, the aim of the present study was to characterize native E. muticus populations. The study was performed with five "capim-carona" populations collected in the state of Rio Grande do Sul, totaling 50 plants grown in pots in the Agronomy School. All five E. muticus populations presented variability for phenotypic traits and phenolic compound concentration. The presence of citral was identified in all populations, except in that from the "Morro da Polícia" region. RAPD analysis showed high variability for these populations, allowing the separation of individuals into five groups according to their geographic origin. The highest variability occurred within each population. Based on the results, the populations from São Borja and Agronomy School can be recommended to be used in breeding programs.

-Elionurus muticus is a native aromatic grass from the Pampa biome that produces an

Genetic variability is the basis of plant breeding. In corn, a large and diverse genetic pool permits manipulation of different genotypes, but the genetic diversity of tropical