Location: Tropical Crops and Germplasm Research2012 Annual Report
1a. Objectives (from AD-416):
In cooperation with staff at the ARS Plant Genetic Resources Conservation Unit, Griffin, Georgia, conserve and distribute a wide spectrum of sorghum genetic diversity and associated information to researchers and breeders worldwide. Phenotypically evaluate sorghum genetic resources for priority morphological and phenological characters, disease resistance, and other priority agronomic traits, and incorporate data into GRIN and/or other databases.
1b. Approach (from AD-416):
Conduct field seed increase to regenerate approximately 500 sorghum accessions with critically low seed quality or quantity to conserve the collection. Use technical information derived from sorghum germplasm evaluations to assist NPGS staff to aid in the conservation, introduction, and distribution of sorghum germplasm. Phenotypically evaluate the 1,227 sorghum accessions from the Zimbabwe collection and use this information to evaluate genetic diversity for sorghum improvement. Using passport and phenotypic evaluation data develop germplasm subset for disease evaluation to identify ecogeographic regions associated with resistance and develop genetic mapping populations to evaluate genetic diversity for disease resistance.
3. Progress Report:
During this year, progress was made in the evaluation, characterization and identification of new sources of resistance among sorghum accessions from Africa. A replicated trial of 150 sorghum accessions from Ethiopia, South Africa and Burkina Faso was conducted at Isabela, Puerto Rico. Accessions were morphologically characterized and screened for anthracnose and grain mold resistance at Isabela, PR. In addition, a sub-set of 68 accessions from Zimbabwe was evaluated for anthracnose, rust and grain mold for a second consecutive year. Seventy sweet sorghum accessions from National Plant Germplasm System (NPGS) were evaluated for anthracnose resistance and for potential use as biofuel. The genetic control of an anthracnose resistant accession was determined through the analysis of observed segregation in a F2 population.
1. Reaction to rust by sorghum accessions from Zimbabwe. Sorghum rust (Puccinia purpurea) is a foliar disease that affects sorghum crop productivity worldwide. The use of resistant sources is the most effective and stable way to control the disease. In this study, 68 sorghum accessions from the Zimbabwe collection maintained by the USDA-ARS, Plant Genetic Resources Conservation Unit at Griffin, Georgia, were evaluated in Isabela, Puerto Rico, during two planting seasons in 2011 to identify new sources of rust resistance. Across the two growing seasons, 12 accessions showed resistance, 15 accessions exhibited a moderately susceptible response, and 41 accessions showed a susceptible response. Variation in disease response was observed within and between experiments for 37 accessions. No rust infection was detected on PI482787 across the two growing seasons, while accession PI482795 exhibited the highest rust infection. This work identified new sources of rust resistance, and shows that PI482787 possess gene(s) for rust resistance and that this accession could be used in sorghum improvement breeding programs.