Résumé
Spatiotemporal monitoring of multiple rice diseases in western Burkina Faso: high frequency of co-occurrences and rapid turnover of viral populationsMariam Barro1, Abalo Itolou Kassankogno1, Drissa Sérémé1, Issa Wonni1, Estelle Billard2, Martine Bangratz2, Nils Poulicard2, Charlotte Tollenaere21 Centre National de Recherche Scientifique et Technologique (CNRST), Institut de l’Environnement et de Recherches Agricoles (INERA), 01 BP : 910 Bobo Dioulasso 01, Burkina Faso 2 PHIM Plant Health Institute, Univ Montpellier, IRD, CIRAD, INRAE, Institut Agro, Montpellier, FranceUnderstanding the spatiotemporal dynamics of diseases and identifying risk factors is of paramount importance in guiding the deployment of effective control measures. We conducted the present study between 2016 and 2019 in western Burkina Faso in three geographical areas, each of which included one irrigated perimeter, and a nearby lowland. Symptom monitoring annually at the same developmental stage showed that bacterial leaf streak (BLS) disease and rice blast were preferentially found in irrigated areas, compared to rainfed lowlands. High levels of co-occurrences were found between the four rice diseases under study, particularly in irrigated areas.The rice yellow mottle disease, due to the RYMV, is not affected by the rice production system, but instead by the specific site. Partial sequencing of a set of 132 samples revealed a very high genetic diversity, with the co-occurrence of four distinct lineages at small geographical scale. One of these lineages results from a recombination event between two others. Temporal dynamics suggest an evolution of the relative frequencies of each genetic lineage within the studied period. Aggressiveness estimates were obtained from experimental infections, and differences between isolates likely contribute to explain observed RYMV population evolution.The implications of these results, including the potential consequences of co-occurrences and co-infections for the evolution of pathogen populations, will be discussed.