Screening for Nitrate Reductase-Deficient Mutants in Rice (Oryza sativa L.)

Abstract

To obtain mutants deficient in nitrate reductase (NR) in rice, screening for chlorate resistance was carried out using the mutant lines maintained at the Institute of Radiation Breeding, NIAR, Japan. Of 437 lines tested, four chlorate resistant lines (M819, M821, M1004 and M1009) were selected. Differences in chlorate sensitivity were also observed among the four selected lines. The levels of in vitro NR activity of seedlings in M819 and M821 were below 30% of that of their parent, Norin 8. M819 and M821 were identified as low NR activity lines. NR activity in M1009 was about 80% of that of Norin 8. However, NR activity in M1004 was the same level as that in Norin 8. Seedlings of four selected lines took up nitrate to the same extent or a higher than Norin 8.