Abstract
A paraquat-resistant Arabidopsis mutant, radical-induced cell death1 (rcd1; Overmyer et al., 2000) is caused by mutation in the gene At1g32230. Expression of the rcd1-1 cDNA under the CaMV 35S promoter also increases tolerance to paraquat (Ahlfors et al., 2004), suggesting that rcd1 is a gain-of-function mutation. rcd1-2 was a missense mutation that created a premature stop codon. We carried out genetic complementation test between rcd1-2 and RCD1 over-expression lines. rcd1-2 harboring 35S::RCD1 exhibited weaker defects with respect to paraquat resistance and abnormal morphology than rcd1, indicating that rcd1 mutation was complemented by RCD1 gene. On the other hand, RCD1 over-expression lines also exhibited weak paraquat resistance like the rcd1-1 over-expression lines. These results may suggest that proper regulation of expression level of RCD1 gene is necessary for the wild-type phenotype.
