Status of the resistance of selected rice (Oryzasativa) varieties to bacterial blight strains in Senegal

Rice plays an important role in achieving and maintaining food and nutritional security in the world. However, its productivity is affected by various constraints, including biotic and abiotic stresses, and several socio-economic constraints. Regarding biotic factors, bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae ( Xoo ) is a major bacterial disease that causes severe yield losses of more than 70%, thereby threatening food and income security in most rice growing countries, including Senegal. Optimal control of this disease requires the use of host plant resistance, as it is economical and environmentally sustainable. Nevertheless, in the context of Senegal, the available sources of resistance are limited, and the potential for resistance among Senegalese rice varieties has been inadequately investigated. In this study we evaluated local rice germplasms for resistance to bacterial blight in Senegal. A trial was conducted in glasshouse conditions using a split-plot experimental design with 32 rice varieties as the main factor and five strains of Xanthomonas oryzae pv. oryzae ( Xoo ) as the secondary factor. Seven (07) of the popular rice varieties, including two (02) lowland (TOX 728-1 and BG 90 − 2), four (04) irrigated (ISRIZ 04, ISRIZ 05, ISRIZ 14 and SAHEL 202) and the variety GIGANTE exhibited full resistance against all strains tested. These varieties are suggested to be grown in Xoo -prone areas, and can be used for improving the resistance of other commercial varieties in other regions where Xoo is prevalent. A significant interaction between strains and varieties was detected, suggesting that pathogen race diversity may contribute to the determination of rice resistance to Xoo strains in Senegal. Among all bacterial strains, S82-4-1 of the race S4 exhibited the highest virulence. This strain can be used as reference for screening rice varieties in West-Africa.