Characterization of blast resistance in a diverse rice panel from sub-Saharan Africa

There is a recent unparalleled increase in demand for rice in sub-Saharan Africa, yet its production is affected by blast disease. Characterization of blast resistance in adapted African rice cultivars can provide important information to guide growers and rice breeders. We used molecular markers for known blast resistance genes ( genes; =21) to group African rice genotypes ( =240) into similarity clusters. We then used greenhouse-based assays to challenge representative rice genotypes ( =56) with African isolates ( =8) of which varied in virulence and genetic lineage. The markers grouped rice cultivars into five blast resistance clusters (BRC) which differed in foliar disease severity. Using stepwise regression, we found that the genes associated with reduced blast severity were and , while , , and were associated with increased susceptibility. All rice genotypes in the most resistant cluster, BRC 4, possessed and , the only genes that were significantly associated with reduced foliar blast severity. Cultivar IRAT109, which contains was resistant against seven African isolates, while ARICA 17 was susceptible to eight isolates. The popular Basmati 217 and Basmati 370 were among the most susceptible genotypes.These findings indicate that most tested genes were not effective against African blast pathogen collections. Pyramiding genes in the multifamily blast resistance cluster on chromosome 6 and on chromosome 11 could confer broad-spectrum resistance capabilities. To gain further insights into genomic regions associated with blast resistance, gene mapping could be conducted with resident blast pathogen collections.