ABSTRACT. Agronomic performance and external and internal appearance of watermelon (Citrullus lanatus) fruit are important traits that should be taken into consideration during the development of a new cultivar, as well as being the principal identification elements used by the consumer, which are based on the external appearance and quality of the fruit. Externally, the fruit can be characterized in terms of the shape, the color of the lower rind, and the presence of grooves and stripes, the stripes can be classified as clearly defined or diffuse. The objective of this study was to identify microsatellite markers linked to the stripe pattern of watermelon fruit to support watermelon improvement programs, with the selection of this characteristic in the plantlet stage. F1 and F2 populations, result of a cross between the cultivars BRS Opara (clearly defined stripes) and Pérola (diffuse stripes), were phenotyped for their fruit stripe pattern. The CTAB 2X protocol was used for DNA extraction and 116 microsatellite markers were examined in a group of F2 plants that had fruit with well-defined stripes and fruit with diffuse stripes. The microsatellite loci MCPI_05 and MCPI_16 exhibited a linkage to the stripe pattern at a distance of 1.5 and 1.8 cM, respectively, with LOD scores of 39.28 and 38.11, respectively, which were located on chromosome six of the watermelon genome. These markers can be used in marker-assisted selection in watermelon improvement programs, by various research institutions.

Allelic patterns and genetic similarity among 17 watermelon cultivars were established using microsatellite markers. For visualization of the genetic similarity, the dendrogram UPGMA (Unweighted Pair Group Method with Arithmetic Means) was generated by the similarity matrix of the Jacquard coefficient, based on 34 alleles of ten microsatellite loci. Total DNA was extracted by the CTAB 2x method and PCR (Polymerase Chain Reaction) products were analyzed in denaturing polyacrylamide 6% gels, stained with silver nitrate. The number of base pairs was estimated by the method of inverse mobility, based on known size product regression. Similarity ranged from 34 to 100%, reflecting high genetic variability. Analyzed loci were not enough to distinguish all 17 watermelon cultivars. The pairs 'Sugar Baby' and 'Omaru Yamato', 'Charleston Gray' and 'Sunshade', 'Crimson Sweet' and 'Nova Crimson' presented 100% of similarity. In dendrogram two groups were observed at 0.42 similarity cut point, with Citrullus colocynthis, positioned as an out group. One watermelon group was formed predominantly by cultivars derived from 'Crimson' and another group was formed by cultivars of different types such as 'Sugar Baby', 'Charleston Gray' and 'Pérola'. Allele pattern and base pair (bp) estimates for the 34 alleles in the 10 microsatellite loci revealed in the present study are a first endeavor to use microsatellite markers in situations of cultivar protection for the watermelon agribusiness in Brazil. They can also be used in situations of commercial disputes regarding certification of the main watermelon cultivars used in the country.

The umbu tree (Spondias tuberosa) is one of the best known plants of the Brazilian semi-arid region; it has great potential for the fruit market due to excellent consumer acceptance. This tree is not presently cultivated; fruit commercialization is based on extrativism. Consequently, there has been little research on the genetics of this species. Our objective was to develop, evaluate and transfer single sequence repeat (SSR) loci to S. tuberosa to support work on genetic resources and agronomic improvement of this species. SSR loci for the umbu tree were developed from a new enriched genomic library and evaluated by PCR. Fourteen SSR loci developed for S. radlkoferi were evaluated for use in S. tuberosa, as well as 18 SSR loci previously identified for this species. DNA was extracted from leaf tissue of eight umbu trees available that are part of a germplasm collection located in Petrolina, PE, Brazil. Of the 14 pairs of primers that were tested, six yielded amplicons, and two showed polymorphism in the genotyped samples. All SSR loci of S. radlkoferi transferred to the umbu tree species, yielding amplicons; however, only four were polymorphic in this sample. Among the eighteen available species-specific SSR loci, six were polymorphic ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 20 (2): gmr18778 V.N. Santos et al. 2for these eight trees. Among the 38 loci that we evaluated, 12 were polymorphic in the sample, including two new loci for S. tuberosa.The number of alleles ranged from 2 to 12, and 10 of them were moderately to highly informative (PIC>0.50), while nine had heterozygosity greater than 0.50. The six new SSR loci and the 14 SSR loci transferred from S. radlkoferi increase the number of available loci for population studies, germplasm collection and resource management for the development of new umbu tree cultivars.