Evidence map›Paper›PMID 42185990›Full record

ArticleBMC plant biology2026

Uncovering the historic genetic diversity of Ugandan Robusta coffee germplasm: a foundation for core collection design.

Mildred Julian Nakanwagi, Peter Wasswa, Mathieu Gonin, Remi Auguste, Tram Bao Vi, Pascal Musoli, Pierre Marraccini, Catherine Kiwuka, Jeninah Karungi, Isaac Onziga Dramadri and 7 more

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Article in BMC plant biology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

17 authors.

Mildred Julian NakanwagiDepartment of Crop Science and Horticulture, Makerere University, Kampala, Uganda. mildredjuliannakanwagi@gmail.com.
Peter WasswaDepartment of Crop Science and Horticulture, Makerere University, Kampala, Uganda.
Mathieu GoninNational Coffee Research Institute, National Agricultural Research Organisation, Kituza, Mukono, Uganda.
Remi AugusteCIRAD, UMR DIADE, Montpellier, F-34398, France.
Tram Bao ViCIRAD, UMR DIADE, Montpellier, F-34398, France.
Pascal MusoliNational Coffee Research Institute, National Agricultural Research Organisation, Kituza, Mukono, Uganda.
Pierre MarracciniCIRAD, UMR DIADE, Montpellier, F-34398, France.
Catherine KiwukaPlant Genetic Resource Center, National Agricultural Research Organisation, Entebbe, Uganda.
Jeninah KarungiDepartment of Crop Science and Horticulture, Makerere University, Kampala, Uganda.
Isaac Onziga DramadriDepartment of Crop Science and Horticulture, Makerere University, Kampala, Uganda.
Mildred Ochwo SsemakulaDepartment of Crop Science and Horticulture, Makerere University, Kampala, Uganda.
Claude Patrick MilletUMR DIADE, Univ Montpellier, IRD, CIRAD, Montpellier, France.
Ali MiltonNational Coffee Research Institute, National Agricultural Research Organisation, Kituza, Mukono, Uganda.
Geofrey ArinaitweNational Coffee Research Institute, National Agricultural Research Organisation, Kituza, Mukono, Uganda.
Godfrey SserembaNational Coffee Research Institute, National Agricultural Research Organisation, Kituza, Mukono, Uganda.
Boris Delahaie *CIRAD, UMR DIADE, Montpellier, F-34398, France.
Valerie Poncet *UMR DIADE, Univ Montpellier, IRD, CIRAD, Montpellier, France.

Funding

European Union (EU) for the project "Robusta coffee agroforestry to adapt and mitigate climate change in Uganda" (GCCA+-Global Climate Change Alliance & DESIRA Project/Grant No. FOOD/2021/427-759
6 · The paper itself

Abstract

backgroundUganda is a primary centre of diversity for Coffea canephora (Robusta coffee), a crop that underpins both the national coffee sector and global breeding programs. The National Coffee Research Institute (NaCORI) of Uganda conserves more than 2058 accessions that were collected from different agroecological zones of the country. However, their genetic diversity has been only partly characterized, limiting their effective use in conservation and breeding.

resultsA total of 909 C. canephora accessions from the NaCORI collection was genotyped, using 236 KASPar SNP markers. To investigate genetic structure and diversity we combined multivariate analyses, genetic diversity and differentiation metrics as well as hierarchical clustering. Genetic clusters were then spatially mapped according to the agroecological regions of origin across Uganda. Using reference genotypes from known wild Ugandan forests and major African genetic groups we observed that accessions from NaCORI were majorly related to the genetic group O from Uganda (and to a lesser extent Congolese group E). Despite the low differentiation among regional subpopulations of origin, reflecting gene flow driven by historical dissemination and admixture within the collection, the cultivated accessions were separated into six distinct clusters using Ward's hierarchical method. From these genetic clusters, two core collections were designed using Core Hunter 3. The first comprised 109 accessions with high allelic coverage (CV = 0.981), while the second comprised 328 accessions that, in addition to allelic coverage, optimized the representation of both geographical origin and genetic clusters. These corresponded to 13% and 42% of the entire studied collection, respectively. The core collection of 328 accessions was defined as the GWAS population for downstream association studies. Including representative wild Ugandan accessions in the analyses reveals that some forests may harbour unique diversity absent from the cultivated germplasm.

conclusionCharacterizing this diversity and designing representative core and GWAS collections are essential to optimize resource management and enable the targeted development of climate-resilient cultivars. The multi-regional origin of our core collections revealed the influence of ecological and socio-cultural factors on germplasm diversity. Our results also suggest that including wild accessions from Ugandan forests could greatly enhance the cultivated genetic pool.

Indexed as

CoffeaGenetic VariationGenotypePhylogenyPolymorphism, Single NucleotideUgandaCoffea canephoraCore collectionCrop wild relativesEarly culture historiesEx situ conservationGeographical sourcesKASPar markers

Identifiers

PMID42185990
PMCPMC13551851

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.