Are Mission Olives Actually Picholine Marocaine?

Opinion & Commentary

By Liliana Scarafia, on October 18, 2012

Mission olives have spread over California since  their introduction in the late 1700’s to the missions dotting El Camino Real. With time they became the primary cultivar for table olives and olive oil, so widely cultivated that Mission is listed as the only olive cultivar from the United States in the World Catalogue of Olive Varieties. The understanding was that, in spite of its Old World origin, Mission was a different cultivar that underwent genetic changes in the New World and was unlike any other. However, modern DNA fingerprinting techniques suggest otherwise.

In the last decade, olive germplasm banks based in the Mediterranean basin (the ancestral birthplace of the olive) have used DNA techniques to characterize, identify and preserve wild and commercial olive varieties. Such work has been used to settle conflicting cases of synonyms (different names applied to a single cultivar at different locations) or homonyms (the same variety name used for two different cultivars). At Agbiolab we use the same fingerprinting methods to match olive plants that could have been mislabeled or misidentified.

Thus it was surprising that olive samples collected from several Mission olive orchards and from ancient trees shared a DNA fingerprint matching the one from Picholine Marocaine. As its name implies, Picholine Marocaine (not to be confused with Picholine from France, or Redding Picholine from the USA) is the most common variety in Morocco. It shares agronomic and morphological traits with Mission olives, and both are dual purpose olive cultivars that yield good quality oil.

Could this tantalizing genetic finding be corroborated by historical records? Are Mission olives actually Picholine Marocaine? Why were they chosen for the New World missions? We welcome any contribution that can shed some light into this conundrum.

Do you have an opinion you’d like to share in an article? See our submission form and guidelines here.

More articles on: ,

This article was last updated November 23, 2014 - 3:27 PM (GMT-5)

  • Jorge Pereira

    Polyclonal cultivars have been documented in olive. However, it is highly unlikely that differences at one or two DNA fragment sequences could be the result of sexual reproduction in a highly heterozygous, out-crossing species such as olive. Another possible cause of this type of clonal variation is a somatic mutation event occurring as bud sports in the mother cultivar tree, and subsequent clonal propagation. This may explain instances of slight clonal variation found. However, this variation occurs between different accessions not known to be synonyms or closely related–the sole exception is ‘Mission Variant’ with ‘Mission’. These observations suggest misidentification of at least one accession. For example, ‘Zitoum’ is putatively a synonym of ‘Picholine marocaine’, a unique cultivar from Morocco, yet the results suggest that the accession labeled ‘Zitoum’ is actually an incorrectly named, clonal variant of ‘Mission. The cases of synonymy or near synonymy encountered in several study may be the result of accession mislabeling, however, the problem may also lie in the assumption that an olive cultivar is a homogeneous entity. Many olive cultivars have a long history of cultivation in the regions where they were selected by local farmers. Traditional farmers, in the past and still today, develop and name crop cultivars based on distinct phenotypes associated with specific agronomic, morphological, phenological and organoleptic qualities , some of which may be achieved via different genotypes, potentially resulting in heterogeneous cultivars. In the case of olive, the issue is further complicated by: both clonal and seed propagation, changing selection pressures, exposure to new growing environments, gene flow with other cultivars or locally occurring oleasters (O. europaea L. ssp. europaea var. sylvestris (Miller) Lehr.), all of which may result in intracultivar heterogeneity. Additionally, phenotypic or genetic changes may occur, triggering a new name for an extant genotype, or a new genotype for an established name. Finally, germplasm collections may themselves be sources of identification confusions contributing to intracultivar heterogeneity. ‘Mission’, a widely grown main stay of the California olive industry, was first grown in California by Spanish Franciscan missionaries in the eighteenth Century, but its precise origin remains unclear. An analysis with several other ancient and well-established Iberian cultivars: ‘Nevadillo’, ‘Manzanillo’, ‘Cordovil’, ‘Picual’, ‘Verdeal’, and one genotype synonymous among several South American cultivar names (‘Azapa’, ‘Yuaca’, ‘Mission Leiva’, and ‘Mostazal’) shares the most allelic diversity in the DNA sequences. This supports a Spanish origin of ‘Mission’. A comparison of the ‘Mission’ genotype to the above mentioned cultivars and ‘Sevillano’, another widely grown Spanish cultivar, revealed that all could contribute at least one allele to the ‘Mission’ genotype at thirteen or fourteen DNA sequences,, and at all fifteen loci for ‘Sevillano’ suggesting that ‘Mission’ could have originated as a seedling selection of the Iberian germplasm imported to the New World by the Spanish missionaries. Another possibility in the cases of both ‘Zitoum’ and ‘Mission’ accessions is that these are catch-all names that may have included distinct cultivars that at one time were subsumed under those names for ease or because of broad shared characteristics. Another Californian cultivar, ‘Redding Picholine’, is thought to have been imported into California in the late nineteenth century as a rootstock variety initially mistaken for the French ‘Picholine’ scion cultivar analysis places ‘Redding Picholine’ into the cultivar most closely associated with the French cultivar, ‘Rubra’, suggesting that the former cultivar may derive from French germplasm. users. Instances of misidentification or ambiguous identity, as with the ‘Zitoum’ example above, high- light the need for a standardized set of molecular markers used to build a database of verified olive cultivar genotypes a set harmonized with researchers in the Mediterranean and worldwide to ensure robust, globally accurate identities. From: Molecular characterization of genetic diversity, structure, and differentiation in the olive (Olea europaea L.) germplasm collection of the United States Department of Agriculture Anne M. Koehmstedt • Mallikarjuna K. Aradhya • Daniela Soleri • Jenny L. Smith • Vito S. Polito. Genet Resour Crop Evol (2011) 58:519–531 Posted By Jorge Pereira. Genetic Prof. of Agronomy High Scholl. Montevideo Uruguay