Response of Sorghum Accessions from Four African Countries against Colletotrichum sublineolum, Causal Agent of Sorghum Anthracnose

Seventy-two sorghum accessions were randomly selected from the Ethiopia, Mali, Sudan, and Uganda germplasm collections maintained by the US National Plant Germplasm System to evaluate variation in anthracnose resistance. The accessions were planted in a randomized complete block design in College Station, Texas during the 2007 and 2008 growing seasons. Twenty-six accessions exhibited a resistant response across growing seasons with 8 accessions showing a susceptible response. Twenty-nine accessions showed variation in disease response within and between experiments. Seven accessions were rated as resistant in 2007 but showed a susceptible reaction in 2008. The frequency of resistant germplasm varied based on country of origin with 80% of the accessions from Mali, 48% of the accessions from Uganda, 24% of the accessions from Sudan, and 7% of the accessions from Ethiopia exhibiting a resistance response. When the same accessions were evaluated in Isabela, Puerto Rico, 100% of the accessions from Mali, 43% of the accessions from Uganda, and 28% of the accessions from Sudan exhibited a resistant response. All the accessions from Ethiopia were susceptible to anthracnose when evaluated in Isabela, Puerto Rico. In both locations, 22 accessions exhibited a resistant response. Four accessions rated as resistant in Texas were found to be susceptible in Puerto Rico; whereas, five accessions rated as resistant in Puerto Rico showed a susceptible response in Texas. These results indicated that the Mali, Sudan, and Uganda sorghum collections may be an important source of anthracnose resistance. However, the identification of anthracnose resistant germplasm from many diverse regions could result in the identification of new sources of genetic variation for resistance. Also, greater genetic variation for resistance could be present in regions with a high frequency of resistant germplasm.