SILVOLIVE, a Germplasm Collection of Wild Subspecies With High Genetic Variability as a Source of Rootstocks and Resistance Genes for Olive Breeding.

Pablo Díaz-Rueda,Carlos M Rivero-Núñez,Jose L García-Fernández,Juan D Franco-Navarro,Lorenzo León,Manuel Cantos,Nieves Capote,Angjelina Belaj,Jose M Colmenero-Flores,Rita Messora,Alfonso De Cires,Pablo Aleza,Joaquín Espartero,Guillaume Besnard

doi:10.3389/fpls.2020.00629

Abstract

Wild subspecies of Olea europaea constitute a source of genetic variability with huge potential for olive breeding to face global changes in Mediterranean-climate regions. We intend to identify wild olive genotypes with optimal adaptability to different environmental conditions to serve as a source of rootstocks and resistance genes for olive breeding. The SILVOLIVE collection includes 146 wild genotypes representative of the six O. europaea subspecies and early-generations hybrids. These genotypes came either from olive germplasm collections or from direct prospection in Spain, continental Africa and the Macaronesian archipelago. The collection was genotyped with plastid and nuclear markers, confirming the origin of the genotypes and their high genetic variability. Morphological and architectural parameters were quantified in 103 genotypes allowing the identification of three major groups of correlative traits including vigor, branching habits and the belowground-to-aboveground ratio. The occurrence of strong phenotypic variability in these traits within the germplasm collection has been shown. Furthermore, wild olive relatives are of great significance to be used as rootstocks for olive cultivation. Thus, as a proof of concept, different wild genotypes used as rootstocks were shown to regulate vigor parameters of the grafted cultivar “Picual” scion, which could improve the productivity of high-density hedgerow orchards.

Highlights

The wild relatives of domesticated crops possess genetic diversity useful for developing more productive, nutritious and resilient crop varieties (Castaneda-Alvarez et al, 2016), and for preserving global food security against the serious threat of climate change (Vincent et al, 2013)
The wild olive germplasm collection, called SILVOLIVE, includes 146 genotypes obtained from seeds of mother trees prospected in their natural habitats or maintained in different Olive Germplasm Banks (WOGB-IFAPA Córdoba, WOGB-INRA Marrakech, and CEFE Montpellier; Table 1)
Olives are represented in the SILVOLIVE collection (Figure 1), confirming the wide genetic variability represented in the germplasm collection

Summary

Introduction

The wild relatives of domesticated crops possess genetic diversity useful for developing more productive, nutritious and resilient crop varieties (Castaneda-Alvarez et al, 2016), and for preserving global food security against the serious threat of climate change (Vincent et al, 2013). Wild olives grow in arid and semiarid regions at different altitudes and soil types, including those exposed to severe water deficit, salinity and low temperatures (Cantos et al, 2002; Baldoni et al, 2006; Klepo et al, 2013; Belaj et al, 2016; Chiappetta et al, 2017) This adaptability to adverse environmental conditions makes wild olive trees suitable to grow in marginal soils (e.g., at risk of desertification), to colonize deforested habitats or to rehabilitate devastated regions (Bekele, 2005; Kassa et al, 2019).

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Discussion

Conclusion