Morus nigra - EUFORGEN European forest genetic resources programme

Genetic summary

Genetic diversity and variation

Despite its cultural and economic importance, research on the genetics and conservation of black mulberry remains limited (Kılınçer et al., 2024). Across its range, black mulberry has remarkably low genetic diversity and minimal population structure (Kılınçer et al., 2024; Ismail et al., 2022). Studies consistently report that both wild and cultivated accessions, including those from Europe and surrounding regions, show little genetic variation within the species, although wild black mulberry is genetically distinct from other mulberry species (Ismail et al., 2022).

This low genetic diversity is thought to result from historical genetic bottlenecks, the species’ predominant vegetative propagation, and widespread clonal propagation in cultivation, leading to the formation of clonal populations (Kılınçer et al., 2024). The nearly identical genetic structure observed is highly unusual among domesticated perennial fruit crops and suggests that black mulberry globally lacks genetic variability (Kılınçer et al., 2024).

In Syria, black mulberry cultivars also displayed low overall genetic diversity, reinforcing this pattern of uniformity across its distribution (Baroudi, Choumane, and Makhoul, 2023). The species’ very high ploidy level, specifically decosaploidy (22x), is a unique feature within the genus Morus and among flowering plants, contributing to its distinctive genetic stability and evolutionary isolation (Baroudi, Choumane, and Makhoul, 2023; Kılınçer et al., 2024).

Genetic distribution and clustering

Studies on the genetic structure of black mulberry indicate limited but distinct genetic clustering within certain regions. In Syria, populations have been shown to group into two main genetic clusters (Baroudi, Choumane, and Makhoul, 2023). However, across its broader range, there is a lack of clear correlation between geographical origin and genetic similarity. This pattern results from centuries of human-mediated introduction, cultivation, and later naturalization of mulberry genotypes outside their original centres of diversity (Baroudi, Choumane, and Makhoul, 2023).

Gene flow

Black mulberry is wind pollinated, with seeds being dispersed by birds and other animals, facilitating long-distance gene flow. However, in cultivation the species is often clonally propagated.

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Further relevant genetic traits

Interspecific taxa dynamics

Black-fruited cultivars of white mulberry (Morus alba) are often mistaken for black mulberry, as both can produce dark-coloured fruits and share similar leaf morphologies (Kılınçer et al., 2024). This misidentification complicates both conservation and breeding efforts, as it obscures true patterns of genetic diversity and species distribution.

Molecular and cluster analyses have confirmed that black mulberry forms a distinct genetic group separate from other mulberry species, although it has very high genetic similarity between its own accessions, indicating low intraspecific variation (Ismail et al., 2022). Comparative studies show that white mulberry possesses greater genetic diversity than black mulberry, reflecting its broader distribution, extensive cultivation, and hybridization potential (Baroudi, Choumane, and Makhoul, 2023). Despite their genetic similarity, the two species can be clearly distinguished at the molecular level, supporting their classification as separate taxa (Baroudi, Choumane, and Makhoul, 2023).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Genetic conservation

Threats

Black mulberry has extremely low genetic diversity due to its clonal propagation, making it highly vulnerable to pests, diseases, and environmental change (Kılınçer et al., 2024). This lack of variability limits its adaptability and long-term survival potential. In Europe, where black mulberry is mainly cultivated rather than naturally regenerating, opportunities for gene flow and recombination are minimal. Climate change creates risks and opportunities; warmer and drier conditions may stress existing populations but could also expand suitable habitats northward into Central Europe (Švagr et al., 2023). Additional threats include fungal pathogens and insect pests, although their current impact in Europe remains limited (Švagr et al., 2023). The species’ restricted genetic base and dependence on vegetative propagation represent major concerns for its conservation and resilience.

Management

Conservation of black mulberry should prioritize the preservation of ancient and heritage trees, which may contain rare genetic variants (Kılınçer et al., 2024). Ex situ germplasm conservation and molecular characterization are essential to safeguard remaining diversity and clarify species identification, especially where confusion with white mulberry exists (Baroudi, Choumane, and Makhoul, 2023). Although genetic improvement through cross-breeding or new rootstocks could enhance commercial use, such interventions risk compromising genetic integrity (Kılınçer et al., 2024). In situ protection, propagation from diverse source trees, and genetic monitoring are key to maintaining the species’ limited diversity while supporting its continued cultural and ecological value.

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Morus nigra
Morus nigra

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Interspecific taxa dynamics

Genetic conservation

Threats

Management

Further reading

References

Morus nigraMorus nigra

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Interspecific taxa dynamics

Genetic conservation

Threats

Management

Further reading

References

Morus nigra
Morus nigra