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Significance This study provides a deep population genomic analysis of 10,000 Capsicum accessions held in genebanks and representing a frame of the global diversity of the genus. By combining single nucleotide polymorphisms (SNPs) based data and passport information, we investigated the genomic diversity and population structure of wild and domesticated peppers, tracing back to routes of evolution and providing a model of Capsicum annuum distribution, which reflects human trade and historical/cultural influences. Our results highlight west–east routes of expansion, shedding light on the links between South and Mesoamerica, Africa, and East/South Asia, the latter two constituting important diversification centers of pepper diversity. Finally, we outline a roadmap for genebank management and future direction for better exploitation of germplasm resources., Genebanks collect and preserve vast collections of plants and detailed passport information, with the aim of preserving genetic diversity for conservation and breeding. Genetic characterization of such collections has the potential to elucidate the genetic histories of important crops, use marker–trait associations to identify loci controlling traits of interest, search for loci undergoing selection, and contribute to genebank management by identifying taxonomic misassignments and duplicates. We conducted a genomic scan with genotyping by sequencing (GBS) derived single nucleotide polymorphisms (SNPs) of 10,038 pepper (Capsicum spp.) accessions from worldwide genebanks and investigated the recent history of this iconic staple. Genomic data detected up to 1,618 duplicate accessions within and between genebanks and showed that taxonomic ambiguity and misclassification often involve interspecific hybrids that are difficult to classify morphologically. We deeply interrogated the genetic diversity of the commonly consumed Capsicum annuum to investigate its history, finding that the kinds of peppers collected in broad regions across the globe overlap considerably. The method ReMIXTURE—using genetic data to quantify the similarity between the complement of peppers from a focal region and those from other regions—was developed to supplement traditional population genetic analyses. The results reflect a vision of pepper as a highly desirable and tradable cultural commodity, spreading rapidly throughout the globe along major maritime and terrestrial trade routes. Marker associations and possible selective sweeps affecting traits such as pungency were observed, and these traits were shown to be distributed nonuniformly across the globe, suggesting that human preferences exerted a primary influence over domesticated pepper genetic structure.

International audience

International audience; Eggplants and related germplasm are a barely unveiled genetic treasure, for reasons developed in Chap. 10. Diversity and interspecific crossability researches focused so far on Solanum melongena L., the economic importance of which towers that of the indigenous African S. aethiopicum L. and S. macrocarpon L. and which consequently attracted most of geneticists’ and breeders’ attention. However, as S. melongena shares many connections with eggplant germplasm as a whole, this chapter pays as much attention to this species as to the other cultivated and wild ones. Their genetic and phenotypic diversity is surveyed and critically analysed in order to place the reader at the crossroads between the present knowledge and desirable future researches in terms of both traits of interest to breeders and methods for assessing the diversity. The dense corpus of information about interspecific crossability is organised across several axes. Conventional sexual crosses and somatic hybridisations are presented separately, given both methods yield genetically different interspecific material. The section devoted to sexual crosses begins with a survey of the interspecific barriers, and with an overview of the crossing results that are discussed in their methodological dimensions, in particular the criteria assessing the success or failure of the crossing experiments. Then, the crossing results are structured according to the combinations of crosses within and between cultivated and wild material. Species crossability is discussed with regard to the genepool concept and to relationship between species assessed by phylogenetics. The section ends up with interspecific hybrid by-products such as male sterilities and information on traits genetics. The chapter turns then to somatic hybridisations; this part is structured according to groups of species (e.g. New World species) used as fusion partners of S. melongena, the pivotal taxon for most of the fusion experiments. The conclusions outline the limits of the present knowledge on eggplants germplasm diversity and crossability and suggest potential new research routes on these topics.

In last ten years (1998-2007), the area planted to coconut in the world (average 12 Mha) has shown a decreasing trend (average 1%/year). World coconut oil production has remained at more or less the same level in the last ten years (average 3 MT/year). The study of the coconut commodity chain in Ghana show that this sector is confronted with many constraints: the inadequacy price of coconut oil and the competition with other oleaginous plants; an aging coconut plantation; the impacts of the coconut yellow lethal disease, an important demand in peeled nuts towards Nigeria market and the weak dynamism of its institutional organization. Four commodity chains are moving together: the commodity chains of the processing of traditional and semi-industrial coconut oil produce little added value. The commodity of fresh nuts produces a higher added value with limited urban market. Finally, the recent export of peeled nuts commodity chain towards Nigeria offers a large market and brings an important added value to the smallholders. Despite a replanting project in hybrid coconuts, the rehabilitation/ replanting of coconut plantation remains one of the challenges to deal with, in order to boost the coconut commodity chain in Ghana. The observation is that smallholders have not taken up the challenge after the public interventions have seized, in order to rehabilitate or replant their coconut trees. The strategy developed does not sufficiently lay on the market signal which today has evolved. The improved material available and the tested technologies should allow the boosting of the production sector and the reduction of the vulnerable conditions of household affected or threaten by the disease. The same way, the divergent strategies of stakeholders of the coconut commodity chain in Ghana slow down the dynamic of reorientation of this sector towards the export of peeled nuts. Producers in particular, should take advantage of this lucrative commodity chain. It is about all the stakeholders having interest in this commodity chain by preserving the coconut oil sector, which shows an economic, but also considerable social dimension. The boost of this production passes necessarily through the support function of the production and through professional organizations of producers.