Développement d'une méthodologie pour appuyer l’analyse des risques des phytovirus en République démocratique du Congo

Details

Supervisors

Bragard, Claude

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

enPlant viral diseases represent one of the major constraints to agricultural production and food security in the Democratic Republic of the Congo (DRC). Despite their economic and phytosanitary significance, data on plant viruses present in the country remain fragmented, outdated, and often based on obsolete nomenclatures. The objective of this thesis was to contribute to a better understanding and surveillance of plant viral diseases in the DRC through the development of a centralized, standardized, and usable database of information collected on plant pathogenic viruses reported in the country, linking the old nomenclature to current taxonomic standards defined by the ICTV. A comprehensive literature review based on scientific articles, reports, and historical virological databases identified 71 plant pathogenic viruses either confirmed or suspected in the DRC, distributed across 19 viral families and 30 distinct genera. Among these viruses, 70 species are officially recognized by the ICTV, while one recently described species, Cassava Congo cheravirus, remains pending taxonomic validation. The results show a predominance of the Potyviridae and Geminiviridae families, reflecting the importance of viruses transmitted by insect vectors in tropical agroecosystems. The most affected crops are primarily cassava (Manihot esculenta), banana (Musa spp.), and tobacco (Nicotiana tabacum). Analysis of the vectors highlights the major role of Bemisia tabaci in the dissemination of the identified viruses. Vegetative transmission is the primary mode of spread observed, followed by mechanical transmission, which is a key factor in the spread and persistence of viral infections in production systems, making their management particularly complex. As part of this study, a web platform called “Mlinzi,” accessible via www.mlinzidata.com, was developed to centralize and make use of the collected data. This platform allows users to access taxonomic, biological, and epidemiological information regarding plant viruses present in the DRC and neighboring countries. Furthermore, a regional analysis identified 45 phytopathogenic viruses already reported in neighboring countries but not yet officially reported in the DRC. The presence of common vectors, cross-border trade in plant material, and favorable agroecological conditions suggest a risk of these viruses being introduced into the country. This work thus constitutes an important contribution to phytosanitary surveillance, to knowledge of viral diversity, and to the development of digital tools for managing plant viral diseases in the Democratic Republic of the Congo.