Genome Sequence of the Soybean Symbiont Sinorhizobium fredii

Sinorhizobium frediiHH103 is a fast-growing rhizobial strain that is able to nodulate legumes that develop determinate nodules, e.g., soybean, and legumes that form nodules of the indeterminate type. Here we present the genome of HH103, which consists of one chromosome and five plasmids with a total size of 7.22 Mb. Soybean-nodulating bacteria are alphaproteobacteria be-longing to the genera Bradyrhizobium, Mesorhizobium, Rhi-zobium, and Sinorhizobium (5, 9–11). Sinorhizobium fredii HH103 is a fast-growing rhizobial strain with a generation time of about 3 to 4 h, which was isolated from Chinese soil from Hubei Province (3). The strain is able to form nodules on ag-ronomically advanced soybean cultivars (3, 7). Competition studies revealed that in an acid soil the slow-growing Bradyrhi-zobium japonicum strain 110 outcompetes HH103, whereas in alkaline soils most of the nodules are colonized by HH103 (2). Besides soybean, which forms determinate nodules, HH103 infects a number of other legumes, including Glycyrrhiza ura-lensis, which develops indeterminate nodules (1, 7). Sinorhizo