Te role of Mn-SOD and Fe-SOD genes in the response to low temperature in chs mutants of Arabidopsis

Abstract

To determine whether the expression of iron superoxide dismutase ( Fe-SOD ) and manganese superoxide dismutase (Mn-SOD ) increase superoxide-scavenging capacity, and thereby improve the survival rate of chilling sensitive (chs) mutants of Arabidopsis,4 chs mutant (chs1-1 , chs1-2 , chs2-1 , and chs2-2 ) and wild-type plants were grown under low (chilling, 13 °C; cold, 4 °C) and normalgrowth (23 °C) temperatures. Photosynthetic parameters were investigated following treatment with chilling, cold, and normal growthconditions. Chlorophyll content and maximum quantum efciency of PSII primary photochemistry (Fv/Fm) were reduced in plantsgrown at chilling stress. Te degree of chilling sensitivity of chs1 mutant plants was signifcantly greater than that of wild-type and chs2mutants, as measured by chlorophyll fuorescence value and chlorophyll content. MSD1 was expressed during chilling stress in chsmutant and WT plants, while expression of FSD2 and FSD3 SODs in chs mutants was not detected during any of the treatments. Ourresults suggest that MSD1 expression in chs1 -chilled plants responds to chilling, and that the lack of expression of FSD2 and FSD3 genesin chs mutants grown at chilling temperature supports the hypothesis that chloroplasts might be damaged, due to the chs mutation, whenthey are chilled.