Submitted to: Agriculture and Biology Journal of North America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 28, 2010
Publication Date: November 11, 2010
Citation: Erpelding, J.E. 2010. Anthracnose disease response in the Burundi sorghum germplasm collection. Agriculture and Biology Journal of North America. 1(6):1119-1125. Interpretive Summary: Anthracnose is a fungal disease of sorghum that has economic importance worldwide. Disease symptoms are typically observed on leaves of the sorghum plant, but infection can also occur on the seed, panicle, and stalk. Plant death has been observed in Puerto Rico from anthracnose infection of highly susceptible germplasm lines. In the United States, resistant varieties are available and recommended for regions with favorable climatic conditions that could result in disease epidemics. One problem associated with breeding resistant sorghum varieties for anthracnose is frequent genetic changes within the pathogen population which can result in a loss of resistance. Therefore, multiple sources of resistance need to be identified to have a diverse gene pool of resistant germplasm available, which is essential for the development of new varieties. The sorghum germplasm collection from Burundi maintained by the USDA-ARS, National Plant Germplasm System was evaluated at the USDA-ARS, Tropical Agriculture Research Station in Isabela, Puerto Rico to identify anthracnose resistant lines. From the 148 germplasm lines evaluated, 89 showed resistance during the two-year evaluation and would be useful for breeding new anthracnose resistant varieties. The resistant lines showed reddening of inoculated leaves and this production of red pigmented compounds resulted in death of the fungus preventing further disease development. Also, infection severity, or the amount of disease observed on the infected leaves, was very low for the susceptible lines within the collection and these lines could be useful for breeding disease resistant varieties. These results would indicate that Burundi is an important source of anthracnose resistant germplasm. Additionally, the results of this study support previous research, which showed that sorghum germplasm from regions of Africa with high annual rainfall, such as Burundi, are frequently resistant to anthracnose.
Technical Abstract: The United States National Plant Germplasm System maintains 151 sorghum accessions from Burundi of which 148 accessions were evaluated for resistance to Colletotrichum sublineolum at the Tropical Agriculture Research Station in Isabela, Puerto Rico in replicated evaluations during the 2007 and 2008 growing seasons. For the 2007 evaluation, 120 accessions showed a resistant response with 89 of these accessions rated as resistant in 2008. Mean infection severity based on the percentage of infected leaf area for the susceptible accessions was 2% in 2007 and 2.5% for the 2008 evaluation. Only four accessions showed an infection severity more than 10% and eight accessions showed a susceptible response across replications and growing seasons. For the 51 accessions that showed variation in disease response across replications and growing seasons, climatic variation between seasons coupled with the low infection severity observed for these accessions could have contributed to the observed variation. Results of this study indicate that sorghum germplasm from Burundi is an important source of anthracnose resistance for sorghum improvement and that germplasm from regions of high annual rainfall is frequently associated with anthracnose resistance.