Submitted to: Tropical and Subtropical Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 22, 2008
Publication Date: December 15, 2008
Citation: Erpelding, J.E. 2008. Field evaluation of anthracnose disease response for the sorghum germplasm collection from the Kayes region of Mali. Tropical and Subtropical Agroecosystems. (8):291-296. Interpretive Summary: Anthracnose is a fungal disease of sorghum that appears as lesions on infected leaves. In the United States, sorghum anthracnose is of economic importance in the southern plains and southeastern states were climatic conditions are favorable for disease epidemics. Sorghum anthracnose can be successfully controlled using resistant cultivars. However, due to rapid changes in the pathogen population and a lack of genetic diversity in the host plant for disease resistance, anthracnose infection can develop on cultivars that were once resistant. One strategy to reduce the loss of resistance is to combine multiple genes for resistance into a single cultivar; however, additional sources of resistance are needed to develop of these cultivars. An important source for the identification of new genes for anthracnose resistance is the sorghum collection maintained by the USDA, ARS National Plant Germplasm System. Anthracnose field evaluations of the germplasm collection are being conducted at the USDA, ARS Tropical Agriculture Research Station in Isabela, Puerto Rico, but with more than 43,000 germplasm lines in the collection, additional information is needed to aid in germplasm selection. The sorghum collection from the Kayes region of Mali was selected for anthracnose evaluation to identify new sources of resistance and to determine if weather patterns in the country of origin could be successfully used to aid in germplasm selection for disease evaluation; thus, increasing the likelihood of identifying new sources of resistance. From the Kayes region, 277 germplasm lines were evaluated and 119 lines showed resistance to anthracnose infection over multiple growing seasons. Additionally, the frequency of resistant germplasm lines was associated with annual rainfall in the Kayes region. In this region of Mali, rainfall increases from north to south, with less than 400 mm of annual rainfall occurring in the northern regions and more than 1,100 mm of annual rainfall in the southern regions. The frequency of anthracnose resistant germplasm lines was more than 60% in regions receiving over 800 mm of annual rainfall. In comparison, less the 30% of the germplasm lines from regions receiving less than 800 mm of annual rainfall were resistant to anthracnose. These results indicate that the Kayes region of Mali could be an important source of anthracnose resistant germplasm, that germplasm lines from wetter regions were more frequently associated with anthracnose resistance, and that selection of germplasm from regions receiving over 800 mm of annual rainfall could increase the likelihood of identifying new sources of anthracnose resistance.
Technical Abstract: Sorghum germplasm from the Kayes region of Mali maintained in the USDA, ARS National Plant Germplasm System was inoculated with Colletotrichum sublineolum and evaluated for foliar anthracnose resistance in 2003 and 2004 at the USDA, ARS Tropical Agriculture Research Station in Isabela, Puerto Rico. From the 277 accessions evaluated, 119 showed a resistant response over multiple growing seasons. The frequency of anthracnose resistant accessions varied based on region of origin. Germplasm from the Kenieba and Kita administrative districts showed the highest frequency of resistance, with more than 65% of the accessions conferring a resistant response. The frequency of resistant germplasm ranged from 24 to 44% for the other administrative districts. Resistant germplasm was also more frequent in areas experiencing higher annual rainfall. More than 60% of the accessions conferred a resistant response in areas receiving over 800 mm of annual rainfall. In comparison, less than 30% of the accessions conferred a resistant response in areas receiving less than 800 mm of annual rainfall. Results of the evaluation would suggest that the Kayes region of Mali is an important source of anthracnose resistant germplasm and that ecogeographic information could aid in the selection of germplasm to increase the likelihood of identifing new sources of resistance.