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J.I. Hormaza, L. Dollo, and V.S. Polito

The Random Amplified Polymorphic DNA (RAPD) technique was used to develop molecular markers linked to sex expression in Pistacia vera, a dioecious species. Progenies from two female parents (`Lassen' and `Kerman') pollinated by a common male parent (`Peters') were studied. Two bulks of DNA were made in each cross, one from males and one from females. DNA was extracted from each bulked sample as well as from each of the contributing individuals and from 14 additional P. vera cultivars. Twelve hundred decamer oligonucleotide primers were used to perform DNA amplification on the bulk DNA. This analysis led to the identification of one primer (OPO08) that produces a 945 bp. amplification band present only in females and absent in males. The relationship between band presence and female sex expression was conserved in every individual obtained from the two crosses and in 14 cultivars unrelated to the crosses. This band, which we propose is tightly linked to the gene(s) controlling sex determination, provides a reliable marker for sex of pistachio seedlings and should be a useful tool in pistachio breeding.

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A. Fabbri, J.I. Hormaza, and V.S. Polito

We have been screening olive (Olea europea L.) cultivars using the Random Amplified Polymorphic DNA (RAPD) technique. We examined 23 olive cultivars selected to represent the important olive-growing regions of the world. These include oil and table olive cultivars originating from throughout the Mediterranean area. A high degree of polymorphisms is evident in the olive germplasm we examined. Early results indicate that polymorphisms that exist within the species are sufficient to enable efficient development of RAPD markers for distinguishing olive cultivars.

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J.I. Hormaza, L. Dollo, and V.S. Polito

The Random Amplified Polymorphic DNA (RAPD) technique was used to characterize 15 cultivars of pistachio (Pistacia vera L.). A total of 37 polymorphic markers were considered in this study. Each cultivar exhibited a unique molecular phenotype and, as a consequence, can be uniquely fingerprinted. A similarity and cluster analysis based on the amplified fragments produced two distinct groups which are consistent with the known geographical origin of the cultivars. Our results suggest that RAPD analysis can provide a new alternative for cultivar identification and classification of pistachio.

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A. Fabbri, J.I. Hormaza, and V.S. Polito

Seventeen olive (Olea europaea L.) cultivars, including oil and table olive cultivars originating from throughout the Mediterranean area, were screened using random amplified polymorphic DNA (RAPD) markers. The results indicate that a high degree of polymorphism is evident in the olive germplasm reexamined. Forty random decamer primers were screened; seventeen of these produced 47 reproducible amplification fragments useful as polymorphic markers. Each of the 17 cultivars can be discriminated with a few primers. Results were analyzed for similarity among the cultivars and a cluster analysis was performed. These analyses revealed two main groups: one comprising primarily small-fruited cultivars grown mainly for oil production, and the other characterized by having large fruit. There was no apparent clustering of olive cultivars according to their geographic origins.

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P. Escribano, M.A. Viruel, and J.I. Hormaza

Cherimoya (Annona cherimola Mill.) is an underused fruit crop with a clear niche for expansion in subtropical climates. In this study, 16 simple sequence repeat (SSR) loci were used to find molecular polymorphisms among 279 cherimoya accessions from a worldwide ex situ field germplasm collection. A total of 79 amplification fragments were amplified with 16 pairs of SSR primers, with an average of 4.9 bands/SSR. Mean expected and observed heterozygosities averaged 0.53 and 0.44, respectively. The total value for the probability of identity was 4.34 × 10−8. The SSRs studied resulted in 267 different fingerprinting profiles, of which 258 were unique genotypes; the rest were putative cases of synonymies or mislabeling errors. Unweighted pair group method with arithmetic averages (UPGMA) cluster analysis indicated the relationships among the analyzed accessions, showing some specific groups related to their geographical origins. Analysis of molecular variance (AMOVA) was performed to examine the distribution of genetic variation of the 148 accessions collected from putative cherimoya origin areas in Ecuador and Peru, showing that the major variations occurred within valleys in each country. The results confirmed the usefulness of microsatellites for identification of genetic diversity and geographic origin of cherimoya and are discussed in terms of their implications for ex situ conservation of cherimoya genetic resources.