Development and transferability of microsatellite loci for Spondias tuberosa (Anacardiaceae: Sapindales), a species endemic to the Brazilian semi-arid region
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 for 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.