Fig. 2. Genetic distance among 91 blast resistant rice accessions and eleven controls (capitalized) as revealed by UPGMA cluster analysis and Nei (1972). The two main clusters are identified as I and II with sub-clusters denoted with letters (A-F). The controls included ten selected U.S. rice cultivars and Te Qing, which originated in China and is used as a parent in some U.S. breeding programs. Accessions in bold italics were identified as resistant to all blast isolates tested and not having one of the R-genes, Pi-b and/or Pi-ta.