Introduction: Spondias tuberosa is a tree endemic to the semiarid region of Brazil with fruticulture potential. Objective: To estimate the diversity and genetic structure of S. tuberosa accessions from four areas of the semiarid region of Brazil, in order to facilitate conservation genetic resources studies in this species. Methods: DNA was extracted, using the CTAB 2x method, from leaf samples of 24 accessions of S. tuberosa available in the germplasm bank at Embrapa Semiárido, Brazil. Ten microsatellite loci were used in this study. Results: The UPGMA dendrogram, generated with a Jaccard coefficient similarity matrix, contains four groups at a 0.44 cutoff point. The similarity coefficient ranged from 0.30 to 0.84, indicating great divergence among the accessions. A Bayesian analysis conducted with the software Structure suggests there are two subpopulations, one formed by accessions from the Januária region and another by accessions from the Juazeiro, Uauá and Petrolina regions. The ΦST value of 0.12 for the analysis of molecular variance indicates moderate genetic differentiation among the four populations, suggesting that the genetic variability is moderately structured in function of region. Conclusions: Together, the analyses indicate that the genetic diversity of S. tuberosa is not uniformly distributed in the studied regions. Thus, germplasm from a greater number of populations should be collected to increase the germplasm bank genetic diversity of the species.

The umbu tree (Spondias tuberosa) is endemic to the Brazilian semiarid region. This species is not cultivated and commercialized fruits are a result of extrativism; consequently little has been done to develop new and more productive cultivars. Hybrids of different accessions are a result of natural open pollination, so identifying putative male parents among progenies of umbu tree accessions is difficult. Eight accessions were pre-selected for larger fruit size and clones were established at Petrolina, PE. Female plants were randomly chosen among accessions of an established umbu tree experimental plot. Alleles of putative male parents were evaluated based on simple sequence repeat (SSR) loci. Of the 32 SSR loci evaluated, 10 showed polymorphism. Thirty-four alleles were identified, with an average of 3.4/locus. Polymorphism information content ranged from 0.195 to 0.744; the expected ranged from 0.233 to 0.825 and the observed heterozygosity ranged from 0.250 to 0.825. Accessions similarity ranged from 0.44 to 0.68, distributed into two groups: (I) common umbu, BGU30, BGU37, BGU44, BGU55 and BGU68, and (II) BGU 48 and BGU52. Hybrids and self-fertilized V.N. Santos et al. 2 plants were identified among BGU30 and BGU37 progenies; 17 out of 20 and 14 out of 44 hybrids were identified by SSR loci in the BGU30 and BGU37 progenies, respectively. The putative hybrids BGU30 × BGU48, BGU30 × BGU55, BGU30 × BGU44, BGU30 × BGU68, BGU37 × BGU44, BGU37 × BGU55 and BGU37 × BGU52 have potential for future evaluations, as they were more divergent in the dendrogram or had male parents with higher weight fruits. The 10 SSR loci were sufficient to identify a single parent in 12 of 20 BGU30 hybrids and all 14 BGU37 hybrids, demonstrating the potential of this procedure.

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.