Abstract
Various stress treatments can cause excess active oxygen species (AOS) production. Since generation of AOS is involved in stress-induced injury, enhancement of AOS scavenging activities would confer resistance to stresses to plants. rcd1-2, which is allelic to rcd1-1 (Overmyer et al., 2000), is resistant to paraquat, UV-B and salt stresses because of the enhanced activities of the AOS scavenging enzymes in chloroplasts. On the other hand, rcd1 is more sensitive to ozone fumigation than wild type, and displays programmed cell death after ozone treatment. rcd1 appears to be a mutant that shows stress responses constitutively. Consequently, it accumulates AOS scavenging enzymes without any stresses, and displays programmed cell death even after removal of ozone. RCD1 gene should negatively regulate wide range of stress-related down-stream genes in an unstressed condition.
