RESCATE DE LOS RECURSOS GENÉTICOS DEL CACAO RELACIONADOS CON LA VARIEDAD NACIONAL: EXPLORACIÓN EN LA AMAZONÍA ECUATORIANA (2010-2013)

International audienceTraditional cocoa plantations in Ecuador are mostly composed of a complex mix of highly variable hybrid progenies, which has greatly reduced the population of native trees of the " Nacional " variety, to such a point that they are considered today as heading for extinction, which is increasingly worrying the international chocolate industry. Some years ago, we used genetic molecular markers to identify trees considered to be relics of the ancient original population of the " Nacional " variety, and some wild cocoa trees in a particular region of the southern Ecuadorian Amazon were identified as highly related to the " Nacional " variety. This paper presents the results of two surveys carried out in the southern Ecuadorian Amazon, in the Zamora-Chinchipe Province, in 2010 and 2013. The objective of these surveys was to search for, identify and rescue cocoa trees that might be the wild ancestors of the " Nacional " variety. In 2010, 83 mother trees were collected (budwood, pods and leaves) and 48 in 2013. They were preserved at the Granja Domono experimental farm, near Macas (Morona-Santiago province) and at the Tropical Experimental station Pichilingue, near Quevedo. The trees collected are currently being characterized for their genetic diversity, using molecular markers, and for the biochemical diversity of their beans.Las plantaciones tradicionales de cacao están compuestas en su mayoría de una mezcla compleja de progenies híbridas con un alto gradode variabilidad, lo que ha reducido las poblaciones de árboles nativos de la variedad “Nacional”, a tal magnitud que ahora se consideranen vía de extinción, lo que preocupa a la industria chocolatera mundial. Hace algunos años, se utilizaron marcadores genéticos molecularespara identificar árboles considerados como reliquias de la población original antigua de la variedad “Nacional”, y algunos árbolessilvestres de cacao de una región particular del sur de la Amazonía Ecuatoriana fueron identificados como altamente relacionados conla variedad “Nacional”. Este artículo presenta los resultados de dos exploraciones realizadas en el sur de la Amazonia Ecuatoriana, en laprovincia Zamora-Chinchipe, en los años 2010 y 2013. El objetivo de estas exploraciones fue buscar, identificar y rescatar los árboles decacao que pudieran ser los ancestros silvestres de la variedad “Nacional”. En el 2010, 83 árboles madres fueron recolectados (yemas, mazorcasy hojas) y 48 en el 2013. Las muestras fueron preservadas en la granja experimental Granja Domono, cerca de Macas (Provinciade Morona Santiago) y en la Estación Experimental Tropical Pichilingue, cerca de Quevedo. En la actualidad, los árboles recolectadosestán siendo caracterizados en su diversidad genética mediante la utilización de marcadores moleculares y también están siendo caracterizadosen cuanto a la diversidad bioquímica de sus granos

Towards the understanding of the cocoa transcriptome: Production and analysis of an exhaustive dataset of ESTs of Theobroma cacao L. generated from various tissues and under various conditions

Theobroma cacao L., is a tree originated from the tropical rainforest of South America. It is one of the major cash crops for many tropical countries. T. cacao is mainly produced on smallholdings, providing resources for 14 million farmers. Disease resistance and T. cacao quality improvement are two important challenges for all actors of cocoa and chocolate production. T. cacao is seriously affected by pests and fungal diseases, responsible for more than 40% yield losses and quality improvement, nutritional and organoleptic, is also important for consumers. An international collaboration was formed to develop an EST genomic resource database for cacao. Fifty-six cDNA libraries were constructed from different organs, different genotypes and different environmental conditions. A total of 149,650 valid EST sequences were generated corresponding to 48,594 unigenes, 12,692 contigs and 35,902 singletons. A total of 29,849 unigenes shared significant homology with public sequences from other species. Gene Ontology (GO) annotation was applied to distribute the ESTs among the main GO categories. A specific information system (ESTtik) was constructed to process, store and manage this EST collection allowing the user to query a database. To check the representativeness of our EST collection, we looked for the genes known to be involved in two different metabolic pathways extensively studied in other plant species and important for T. cacao qualities: the flavonoid and the terpene pathways. Most of the enzymes described in other crops for these two metabolic pathways were found in our EST collection. A large collection of new genetic markers was provided by this ESTs collection. This EST collection displays a good representation of the T. cacao transcriptome, suitable for analysis of biochemical pathways based on oligonucleotide microarrays derived from these ESTs. It will provide numerous genetic markers that will allow the construction of a high density gene map of T. cacao. This EST collection represents a unique and important molecular resource for T. cacao study and improvement, facilitating the discovery of candidate genes for important T. cacao trait variation. (Résumé d'auteur