Browsing by Author "Pascal Musoli"

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Ecological and genomic vulnerability to climate change across native populations of Robusta coffee (Coffea canephora)
(Global Change Biology, 2022-05-08) Rémi Tournebize; Leyli Borner; Stéphanie Manel; Christine N. Meynard; Yves Vigouroux; Dominique Crouzillat; Coralie Fournier; Mohamed Kassam; Patrick Descombes; Christine Tranchant-Dubreuil; Hugues Parrinello; Catherine Kiwuka; Ucu Sumirat; Hyacinthe Legnate; Jean-Léon Kambale; Bonaventure Sonké; Jose Cassule Mahinga; Pascal Musoli; Steven B. Janssens; Piet Stoffelen; Alexandre de Kochko; Valérie Poncet
The assessment of population vulnerability under climate change is crucial for planning conservation as well as for ensuring food security. Coffea canephora is, in its native habitat, an understorey tree that is mainly distributed in the lowland rainforests of tropical Africa. Also known as Robusta, its commercial value constitutes a significant revenue for many human populations in tropical countries. Comparing ecological and genomic vulnerabilities within the species’ native range can provide valuable insights about habitat loss and the species’ adaptive potential, allowing to identify genotypes that may act as a resource for varietal improvement. By applying species distribution models, we assessed ecological vulnerability as the decrease in climatic suitability under future climatic conditions from 492 occurrences. We then quantified genomic vulnerability (or risk of maladaptation) as the allelic composition change required to keep pace with predicted climate change. Genomic vulnerability was estimated from genomic environmental correlations throughout the native range. Suitable habitat was predicted to diminish to half its size by 2050, with populations near coastlines and around the Congo River being the most vulnerable. Whole-genome sequencing revealed 165 candidate SNPs associated with climatic adaptation in C. canephora, which were located in genes involved in plant response to biotic and abiotic stressors. Genomic vulnerability was higher for populations in West Africa and in the region at the border between DRC and Uganda. Despite an overall low correlation between genomic and ecological vulnerability at broad scale, these two components of vulnerability overlap spatially in ways that may become damaging. Genomic vulnerability was estimated to be 23% higher in populations where habitat will be lost in 2050 compared to regions where habitat will remain suitable. These results highlight how ecological and genomic vulnerabilities are relevant when planning on how to cope with climate change regarding an economically important species.
In vitro inhibitory effect of selected fungicides on mycelial growth of ambrosia fungus associated with the black coffee twig borer, Xylosandrus compactus Eichhoff (Coleoptera: Curculionidae) in Uganda
(African Journal of Agricultural Research, 2015-06-04) Godfrey Kagezi; Patrick Kucel; Sammy Olal; Fabrice Pinard; Joseph Seruyange; Pascal Musoli; Africano Kangire
Black coffee twig borer is a new but rapidly spreading insect pest of coffee in Uganda. Female beetles bore into primary branches/twigs and cultivate an ambrosia fungus for feeding their larvae. Thus, controlling the fungus means depriving the brood a source of food. Three fungicides, chlorothalonil (Glider), tebuconazole (Orius 25EW) and dimethomorph + mancozeb (Volar) were evaluated in vitro for their effectiveness in inhibiting mycelial growth of ambrosia fungus associated with the beetle. The pathogen was exposed to four concentrations (1.5x, 1.25x, 1.0x and 0.5x times the manufacturer recommended rate) incorporated into potato dextrose agar using inhibition and food poisoning techniques. The three fungicides inhibited fungal growth to some extent, even at the lowest concentration (0.5x) and percentage inhibition was significantly different (P≤0.05) from each other. Tebucozanole caused 100% growth inhibition irrespective of concentration and technique used while chlorothalonil and dimethomorph + mancozeb caused less than 40% inhibition for both techniques. Therefore, research should determine effectiveness of tebucozanole for suppressing fungal growth under field conditions for diminishing beetle incidence and fungal pathogenic effects in infested branches. This will pave way for integration of use of tebucozanole into overall Integrated Pest Management package (IPM) for the beetle in Uganda.
Viability of Deficit Irrigation Pre-Exposure in Adapting Robusta Coffee to Drought Stress
(Agronomy, 2023-02-25) Godfrey Sseremba; Pangirayi Bernard Tongoona; Pascal Musoli; John Saviour Yaw Eleblu; Leander Dede Melomey; Daphne Nyachaki Bitalo; Evans Atwijukire; Joseph Mulindwa; Naome Aryatwijuka; Edgar Muhumuza; Judith Kobusinge; Betty Magambo; Godfrey Hubby Kagezi; Eric Yirenkyi Danquah; Elizabeth Balyejusa Kizito; Gerald Kyalo; Emmanuel Iyamulemye; Geofrey Arinaitwe
Coffea canephora has high but inadequately exploited genetic diversity. This diversity, if well exploited, can sustain coffee productivity amidst climate change effects. Drought and heat stress are major global threats to coffee productivity, quality, and tradable volumes. It is not well understood if there is a selectable variation for drought stress tolerance in Robusta coffee half-sibs as a result of watering deficit pre-exposure at the germination stage. Half-sib seeds from selected commercial clones (KR5, KR6, KR7) and a pipeline clone X1 were primed with deficit watering at two growth stages followed by recovery and later evaluated for tolerance to watering deficit stress in three different temperature environments by estimation of plant growth and wilt parameters. Overall, the KR7 family performed the best in terms of the number of individuals excelling for tolerance to deficit watering. In order of decreasing tolerance, the 10 most promising individuals for drought and heat tolerance were identified as: 14.KR7.2, 25.X1.1, 35.KR5.5, 36.KR5.6, 41.KR7.5, 46.KR6.4, 47.KR6.5, 291.X1.3, 318.X1.3, and 15.KR7.3. This is the first prospect into the potential of C. canephora half-sibs’ diversity as an unbound source of genetic variation for abiotic stress tolerance breeding.