Analysis of Genome Sequence Variations Among Three U.S. Rice Varieties Showing Differential Quantitative Disease Resistance to Bacterial Panicle Blight and Sheath Blight

Abstract

<span style=font-size:11.0pt;font-family: times= new= roman,serif;mso-fareast-font-family:times= roman=>1. Abstract Bacterial Panicle Blight (BPB) and Sheath Blight (SB) are major rice diseases in the southeastern United States, and only quantitative disease resistance is known for these diseases. We analyzed draft genome sequence data for three U.S. rice varieties showing differential disease resistance traits for BPB and SB; Trenasse (long-grain, susceptible to BPB and SB), Bengal (medium-grain, susceptible to BPB and SB), and Jupiter (medium-grain, partial resistance to BPB and SB). Comparative genome sequence analysis along with 50 rice accessions revealed that the three US varieties are genetically close and clustered together, separated from other 50 accessions. According to this analysis, the long-grain semi-dwarf variety Trenasse is a tropical japonica type carrying a fraction of indica genome, while the medium-grain varieties Bengal and Jupiter are admixtures of tropical and temperate japonica types. Consistent with the breeding history and the phenotypic trait in grain-shape (but not with the phenotype in disease resistance), more variations were found in the Jupiter/Trenasse and Bengal/Trenasse pairs compared to the Jupiter/Bengal pair. The whole genome sequence information of these US rice varieties will be a useful resource for genetic studies of disease resistance to BPB and SB as well as development of new disease-resistant lines.