Cm. Zhao et al., A chlorate resistant mutant of rice (Oryza sativa L.) with normal nitrate uptake and nitrate reductase activity, BREED SCI, 50(1), 2000, pp. 9-15
Most mutants lacking nitrate reductase (NR) activity show a chlorate resist
ance, but a mutant line M1004, screened based on chlorate resistance, exhib
ited the same level of NR activity as the wild type Norin 8, Here, we chara
cterized a mutant line M1004 and compared it with a NR deficient mutant lin
e M819 and original cultivar Norin 8, M1004 showed a higher chlorate resist
ance than M819 at a higher chlorate concentration (1 mM), The same level of
NO3- and ClO3- uptake as well as NR-mRNA expression was observed in the mu
tant lines and wild type, NR-mRNA expression was induced in KClO3 solution
although the NR activity was inhibited, M1004 exhibited higher a deactivati
on velocity of NR than the wild type, The results suggested that chlorate r
esistance in M1004 was caused by the rapid deactivation of NR. This chlorat
e resistance was transmitted by a single recessive nuclear gene.