ABSTRACT
Mozambique does not have a tradition of farming Coffea arabica or Coffea canephora, the two species that dominate the worldwide coffee market. However, native coffee plants have been growing spontaneously and in some cases cultivated in the Ibo and Quirimba islands in the north of the country and Inhambane province in the south. Historically there has been confusion over the precise taxonomic classification of these indigenous coffee plants, with different botanists identifying the species as C. racemosa, C. zanguebariae or various synonyms of both. The present research aims to clarify the subject and provide new information on these little-described coffee species which may prove valuable as new breeding material for future cultivars, something that is sorely needed to face the present and future challenges of coffee production. Leaf samples were collected from 40 accessions from Ibo Island, Quirimba Island and Inhambane province. The samples were sequenced by whole-genome technology and WGS reads were filtered to identify relevant SNP variants. Diversity among the samples was assessed by PCA, and a phylogenetic tree including several Coffea species was built using additional data available in public databases. Experimental data confirm the presence of C. zanguebariae as the only coffee species present in both Ibo and Quirimba Islands, while it appears that C. racemosa is exclusive to the southern Inhambane province. The present research provides the most detailed analysis so far on the genetic identity of the traditional Mozambican coffee crops. This is the prerequisite for undertaking further scientific studies on these almost unknown coffee species and for starting agronomic development programs for the economic revival of Ibo and Quirimba islands based on coffee cultivation. Furthermore, these species could provide much-needed genetic material for the breeding of new hybrids with the two main commercial coffee species.
ABSTRACT
Climate change is negatively affecting the coffee value chain, with a direct effect on approximately 100 million people from 80 countries. This has been attributed to the high vulnerability of the two-mainstream species, Coffea arabica and Coffea canephora, to extreme weather events, with notable uneven increases in market prices. Taking into account the narrow genetic plasticity of the commercial coffee cultivars, wild-relatives and underutilized Coffea species are valuable genetic resources. In this work, we have assessed the occurrence of Coffea species in to understand the degree of genetic relationships between Coffea species in the country, as well as the patterns of genetic diversity, differentiation, and genetic structure. Only one wild species was found, C. racemosa, which showed a high level of genetic separation with C. arabica, based on plastid, as well as SSR and SNP analysis. C. arabica presented low levels of diversity likely related to their autogamous nature, while the allogamous C. racemosa presented higher levels of diversity and heterozygosity. The analysis of the functional pathways based on SNPs suggests that the stress signaling pathways are more robust in this species. This novel approach shows that it is vital to introduce more resilient species and increase genomic diversity in climate-smart practices.
