Identification of DNA mutation sites in a high temperature tolerant mutant of USDA110 generated by ion-beam irradiation

Takeda, Kiyoko; Sato, Katsuya; Narumi, Issey*; Otsu, Naoko*; Yokoyama, Tadashi*

With the aims of utilization as a biofertilizer inoculant and elucidation of high-temperature tolerance mechanism of soybean nodule bacteria, we had applied the ion beam breeding technology to a strain () USDA110. Consequently, we obtained a mutant named M14 that was able to maintain high viable cell numbers under high-temperature (42C) for at least 7 days. Genome comparison with USDA110 revealed that (1) 1.27 Mbp inversion mutagenesis and (2) 84 single base mutations were occurred in M14. The acquirement of high temperature tolerance in M14 could be attributed to a large-scale inversion or small-scale mutations in the inverted region, or both.