New insights in the Spanish gene pool of olive (Olea europaea L.) preserved ex situ and in situ based on high-throughput molecular markers

In Spain, several local studies have highlighted the likely presence of unknown olive cultivars distinct from the approximately 260 ones previously described in the literature. Furthermore, recent advancements in identification techniques have significantly enhanced in terms of efficacy and precision. This scenario motivated a new nationwide prospecting effort aimed at recovering and characterizing new cultivated germplasm using high-throughput molecular markers. In the present study, the use of 96 ESTSNP markers allowed the identification of a considerable amount of new material (173 new genotypes) coming from areas with low intensification of production in different regions of Spain. As a result, the number of distinct national genotypes documented in the World Olive Germplasm Bank of IFAPA, Có rdoba (WOGBC-ESP046) increased to 427. Likewise, 65 and 24 new synonymy and homonymy cases were identified, respectively. This rise in the number of different national cultivars allowed to deepen the knowledge about the underlying genetic structure. The great genetic variability of Spanish germplasm was confirmed, and a new hot spot of diversity was identified in the northern regions of La Rioja and Aragon. Analysis of the genetic structure showed a clear separation between the germplasm of southern and northern-northeastern Spain and indicated a significantly higher level of admixture in the latter. Given the expansion of modern olive cultivation with only a few cultivars, this cryptic germplasm is in great danger of disappearing. This underlines the fact that maintaining as many cultivars as possible will increase the genetic variability of the olive gene pool to meet the future challenges of olive cultivation.

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was financially supported by the regional IFAPA projects PR.CRF.CRF201900.004 and PR.CRF.CRF202200.004, partially funded by European Agricultural Fund for Rural Development (EAFRD). The conservation and management of WOGBC IFAPA Córdoba has been financially supported by INIA (RFP 2013-00005; RFP 2017-00007) and IFAPA (PP.PEI.IDF201601.2.; PR.CRF.CRF201900.004) projects. The authors are grateful to all the farmers, associations, researchers, and collaborators at regional, national, and international levels for their help during prospecting and/or reception of new accessions. The authors are also grateful for the EST-SNP genotyping support of staff at UPV/EHU—Scientific Park Maria Goyri Biotechnology Center (Bizkaia, Spain). FJ G-G thanks the Programme of Grants for the Recruitment, Incorporation and Mobility of R+D+i Human Capital within the Andalusian Research, Development and Innovation Plan (PAIDI2020).

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