Is the genetic integrity of wild coffea canephora from ivory coast threatened by hybridization with introduced coffee trees from central africa?

Authors: GNAPI, ESTELLE - University Of Felix Houphouet-Boigny; POKOU, DESIRE - National Center For Agricultural Research (CNRA); LEGNATE, HYACINTHE - National Center For Agricultural Research (CNRA); Zhang, Dapeng; MONTAGNON, CHRISTOPHE - Centro De Cooperation Internationale En Recherche Agronomique Pour Le Development (CIRAD); BERTRAND, BENOIT - Centro De Cooperation Internationale En Recherche Agronomique Pour Le Development (CIRAD); N'GUETTA, SIMON-PIERRE - University Of Felix Houphouet-Boigny

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2022
Publication Date: 4/23/2022
Citation: Gnapi, E.D., Pokou, D., Legnate, H., Zhang, D., Montagnon, C., Bertrand, B., N'Guetta, S. 2022. Is the genetic integrity of wild coffea canephora from ivory coast threatened by hybridization with introduced coffee trees from central africa? Euphytica. 218:62. https://doi.org/10.1007/s10681-022-03004-0.
DOI: https://doi.org/10.1007/s10681-022-03004-0

Interpretive Summary: Robusta coffee (C. canephora) is an outcrossing diploid species in the genus Coffea, and accounts for 43% of the global coffee production. Robusta coffee is less susceptible to pests and disease and has better adaptability to tropical lowland environment. Robusta coffee is indigenously to Western and Central Africa, where two natural genetic groups - Guinean and Congolese are distributed in separated geographical regions. Ivory Coast is the primary center of the Guinean group, but the Guinean gene pool is threatened because of the massive introduction of Congolese cultivars into Ivory Coast over the previous decades. Knowledge of gene-flow between these two genetic groups is essential for sustainable conservation of Robusta coffee genetic resources. In the present study, we assessed the pollen contamination rate in the progenies of a native Guinean population using DNA markers. The results show that the introduced Congolese trees naturally hybridized with the endemic Guinean Robusta coffee trees in Ivory Coast. The mismatched flowering time in these two genetic groups is not a sufficient barrier to genetic crossing. While these inter-group hybrids positively contribute to coffee production in Ivory Coast, they also cause genetic erosion in the wild Guinean gene pool. An integrative approach needs to be developed to alleviate this threat. This study provides baseline information for coffee researchers, breeders and genebank curators, to study and improve the conservation of Robusta coffee genetic resources.

Technical Abstract: Robusta coffee (Coffea canephora) is an important source of income and employment, contributing significantly to the economies of many developing countries. This species is split into two genetic groups: Guinean and Congolese. Ivory Coast is the primary diversification center of the Guinean pool, which offers great potential for genetic improvement of Robusta coffee. However, genetic erosion of this group is currently a threat in this country because of the massive introduction of Congolese accessions in the previous decades. In this work, we analyzed the progenies of isolated population of C. canephora composed of a mix of Guinean and Congolese using SNP markers. The analysis is focus on the male parents’ contribution on open pollination progenies. The result shows that the introduction of cultivars from the Congolese gene pool threat the genetic integrity of wild populations of the native Guinean gene pool. A comprehensive conservation strategy needs to be developed to ensure the integrity of wild population of C. canephora through in situ and/or ex situ conservation.