Anthracnose Resistance in Sorghum Germplasm from the Segou Region of Mali

Abstract

Sorghum (Sorghum bicolor [L.] Moench) germplasm from Mali is an important source of anthracnose resistance, and 59 accessions from the Segou region were inoculated with Colletotrichum sublineolum and evaluated for anthracnose resistance to determine the prevalence of resistant accessions from this region. Disease evaluations were conducted at the Tropical Agriculture Research Station in Isabela, Puerto Rico, during the 2005 and 2009 growing seasons. Twenty-one accessions were rated as resistant across replications and growing seasons and showed reddening of inoculated leaves without acervuli development. These accessions represent new sources of anthracnose resistance for sorghum improvement. Fewer accessions were rated as resistant from the drier, northern Niono district as compared to the San and Segou districts that receive greater annual rainfall, suggesting an ecogeographic association. Additionally, susceptible accessions from the Niono district frequently showed higher mean disease severities than susceptible accessions from the San and Segou districts. Accessions classified as race guinea were more frequently rated as resistant compared to race durra accessions. Mean disease severities were also significantly lower for race guinea accessions. The majority of accessions in the collection were race guinea with most durra accessions collected from the Niono district. However, the frequency of resistant guinea accessions was similar across districts. These results indicate ecogeographic origin and race classification could be used to select accessions for anthracnose screening and to identify regions where resistance is more prevalent for the acquisition of additional anthracnose-resistant germplasm.