A recent study has unveiled the genetic blueprint behind flowering time in olive trees, a crucial trait for fruit production that is increasingly under threat from climate change. By analyzing 318 olive genotypes from across the Mediterranean, researchers identified key genetic loci governing flowering time, shedding light on the complex polygenic control of this trait. These findings not only deepen our understanding of olive tree adaptation but also offer new genetic insights to guide breeding programs in developing climate-resilient olive cultivars.
As a cornerstone of Mediterranean agriculture, olive trees are highly sensitive to temperature shifts, which can significantly alter their flowering patterns. Warmer winters may delay flowering, while unseasonably warm springs can trigger premature blooming, increasing the risk of frost damage and disrupting pollination cycles. With climate change amplifying these challenges, olive production—and the livelihoods of millions who depend on it—faces growing uncertainty. Understanding the genetic basis of flowering time has therefore become a scientific imperative for ensuring the future stability of olive cultivation.
Published (DOI: 10.1093/hr/uhae265) on September 24, 2024, in Horticulture Research , a new study led by researchers from the University of Montpellier and CIRAD, France, in collaboration with Moroccan institutions, has mapped the genetic determinants of flowering time in olive trees. Using genome-wide association studies (GWAS) on 318 diverse olive genotypes, the team pinpointed three significant loci associated with flowering time, paving the way for breeding strategies aimed at improving climate adaptability in olive trees.
The research focused on the full flowering date (FFD), a critical phenological stage closely tied to temperature fluctuations. Leveraging capture sequencing, scientists analyzed genetic data from the Worldwide Olive Germplasm Bank of Marrakech, Morocco, uncovering three robust genetic loci on chromosomes 01 and 04 that account for 7.1%, 6.2%, and 6.5% of flowering time variance, respectively. Despite their modest individual effects, these loci suggest a polygenic regulation of flowering, aligning with similar findings in other perennial fruit crops.
The study further emphasized the power of genomic prediction models, revealing that Ridge Regression (RR) outperformed LASSO in predicting flowering times, reinforcing the polygenic nature of the trait. Additionally, researchers identified three distinct genetic clusters within the olive germplasm, corresponding to eastern, central, and western Mediterranean regions, each exhibiting unique flowering behaviors. This geographical genetic structure provides a crucial framework for targeted breeding efforts.
"Our findings highlight the intricate genetic control of flowering time in olive trees and underscore the potential of genomic tools in breeding for climate adaptation," said Dr. Bouchab Khadari, a leading researcher on the study. "This research marks an important step toward developing olive varieties that can withstand the challenges of a shifting climate."
By pinpointing key genetic loci and deciphering their effects, this study provides a critical foundation for breeding programs aimed at optimizing flowering dates in olive trees. Such advancements could help mitigate the risk of frost damage, enhance pollination synchronization, and ultimately strengthen the resilience of olive cultivation in the face of global warming. Beyond securing olive yields, these insights support the long-term sustainability of Mediterranean agriculture—an industry vital not only to regional economies but also to global food security.
