Olive domestication and diversification in the Mediterranean Basin

Area of Science:

• Agricultural Science
• Genetics
• Mediterranean Flora

Background:

• The olive (Olea europaea ssp. europaea) is a key oil crop in temperate regions.
• The precise origin and domestication history of cultivated olives remain subjects of debate.
• Understanding olive's genetic diversity is crucial for crop improvement and conservation.

Purpose of the Study:

• To investigate the genetic diversity and demographic history of cultivated olives.
• To determine the number and location of domestication events.
• To elucidate the role of admixture in shaping olive germplasm.

Main Methods:

• Genotyping of 387 cultivated and wild olive accessions using 25 simple-sequence repeat (SSR) loci.
• Analysis of genetic relationships and population structure.
• Application of approximate Bayesian computation for demographic modeling.

Main Results:

• Cultivated olives resolved into three primary gene pools (Q1, Q2, Q3) reflecting western, central, and eastern Mediterranean Basin origins.
• Gene pool Q1, from southern Spain, shows evidence of a genetic bottleneck and relation to eastern Mediterranean olives.
• Gene pool Q2 exhibits recent admixture with wild olives, suggesting a potential local domestication event in the central Mediterranean.

Conclusions:

• Olive domestication likely involved multiple events across the Mediterranean Basin.
• Genetic admixture played a significant role in shaping the diversity of cultivated olive varieties.
• The findings provide insights into the complex evolutionary history of this important crop.