Abstract
Wild genetic resources and their ability to adapt to environmental change are critically important in light of the projected climate change, while constituting the foundation of agricultural sustainability. To address the expected negative effects of climate change on Robusta coffee trees (Coffea canephora), collecting missions were conducted to explore its current native distribution in Uganda over a broad climatic range. Wild material from seven forests could thus be collected. We used 19 microsatellite (SSR) markers to assess genetic diversity and structure of this material as well as material from two ex-situ collections and a feral population. The Ugandan C. canephora diversity was then positioned relative to the species’ global diversity structure. Twenty-two climatic variables were used to explore variations in climatic zones across the sampled forests. Overall, Uganda’s native C. canephora diversity differs from other known genetic groups of this species. In northwestern (NW) Uganda, four distinct genetic clusters were distinguished being from Zoka, Budongo, Itwara and Kibale forests A large southern-central (SC) cluster included Malabigambo, Mabira, and Kalangala forest accessions, as well as feral and cultivated accessions, suggesting similarity in genetic origin and strong gene flow between wild and cultivated compartments. We also confirmed the introduction of Congolese varieties into the SC region where most Robusta coffee production takes place. Identified populations occurred in divergent environmental conditions and 12 environmental variables significantly explained 16.3% of the total allelic variation across populations. The substantial genetic variation within and between Ugandan populations with different climatic envelopes might contain adaptive diversity to cope with climate change. The accessions that we collected have substantially enriched the diversity hosted in the Ugandan collections and thus contribute to ex situ conservation of this vital genetic resource. However, there is an urgent need to develop strategies to enhance complementary in-situ conservation of Coffea canephora in native forests in northwestern Uganda.
Highlights
Coffee is a major global commodity and the total value of its industry was estimated to surpass US$200 billion in 2017 [1]
The genetic diversity in Ugandan C. canephora native populations was examined at the 19 simple sequence repeat (SSR) loci and in the 191 C. canephora accessions collected from wild populations (Table 2)
Our results showed that the genetic diversity found within Ugandan wild C. canephora populations was not present elsewhere in the C. canephora distribution range
Summary
Coffee is a major global commodity and the total value of its industry was estimated to surpass US$200 billion in 2017 [1]. The sustainability of Ugandan C. canephora production is of major national and global importance, for smallholder farmers [4]. The sustainability of the global coffee industry is threatened by the adverse effects of climate change, especially drought, rising temperatures, pest and disease pressure [2,5,6]. A global temperature increase of 2.1 ̊ C has been predicted by 2050 [7], while rainfall is expected to become more erratic, with more frequent and severe drought periods, which will render conditions in some coffee growing areas less suitable, seriously affecting coffee production [8,9,10,11]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
