Scientists map the genome of Morocco’s endangered argan tree

Friday 22 August 2025 - 10:20

By: Dakir Madiha

Scientists map the genome of Morocco’s endangered argan tree

A scientific milestone has been achieved as an international team of researchers, including Moroccan scientists, successfully mapped the full genome of the argan tree. This groundbreaking work, the first chromosome-level genome assembly of the species, promises significant advancements in the conservation and sustainable use of one of Morocco’s most iconic natural resources.

Advancing knowledge of a national treasure

The argan tree, Sideroxylon spinosum, is an endemic species essential to Morocco’s ecology and economy. Renowned for its oil, which is prized in culinary and cosmetic markets worldwide, the tree also supports rural livelihoods, particularly women’s cooperatives. However, decades of overgrazing, unsustainable exploitation, and climate change have placed the species under severe strain.

Published this month in Scientific Data (Nature portfolio), the genome project used cutting-edge sequencing technologies, including PacBio HiFi and Illumina Hi-C. The research team independently assembled both parental genomes, achieving a landmark BUSCO completeness score exceeding 97.8%.

“This high-quality assembly provides a valuable resource for future research on argan biology, genetic diversity, and traits relevant to adaptation and oil biosynthesis,” the authors wrote.

Unlocking the biology of the argan tree

The genome reveals critical insights into the tree’s biology. Each haplotype, inherited from the tree’s parents, was resolved into 11 fully assembled chromosomes. Scientists discovered that 60% of the genome is composed of repetitive DNA, while roughly 28,720 protein-coding genes were predicted per haplotype.

Structural variations further distinguish the argan tree from its botanical relatives. Researchers identified a significant inversion on chromosome 2 and evidence of chromosome fusion events in its largest chromosomes (chr1 and chr2). A fully reconstructed chloroplast genome was also produced, correcting errors found in previous studies.

Professor Mohamed Hijri, director of the African Genomics Center at Mohammed VI Polytechnic University (UM6P), called this project “a decisive step toward understanding the evolution, genetic diversity, and adaptation of the argan tree.”

A tool for conservation and agriculture

The genome assembly could revolutionize agricultural practices. A lack of genetic data has long hindered efforts to improve argan tree productivity and oil quality through methods like grafting. The next phase of research will analyze genetic variations across Morocco’s argan tree populations, paving the way for more effective conservation and reforestation strategies.

For Morocco, where the Arganeraie region is recognized as a UNESCO biosphere reserve, this research offers hope amid growing environmental pressures. Hotter summers, prolonged droughts, and erratic rainfall patterns have endangered this fragile ecosystem, exacerbated by surging global demand for argan oil.

The genome also holds promise for exploring traits such as oil quality, drought tolerance, and disease resistance, which will be essential as Morocco adapts to climate challenges.

Open science and international collaboration

In accordance with open science principles, the research team has made its data publicly available. Raw sequencing data can be accessed through the European Nucleotide Archive, annotated genomes on Zenodo, and assembly scripts on GitHub.

The project was supported by the Swiss National Science Foundation and the University of Fribourg, with key contributions from Moroccan institutions, including UM6P and Cadi Ayyad University.

With this genetic blueprint, Morocco now has an invaluable tool to balance the conservation of its natural heritage with the growing economic opportunities presented by global interest in argan oil.