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

Authors: ZAHRA GHARARI, RAMAZANALI KHAVARI NEJAD, REZA SHEKASTE BAND, FARZANE NAJAFI, MOHAMMAD NABIUNI, SAEED IRIAN

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 normal growth (23 °C) temperatures. Photosynthetic parameters were investigated following treatment with chilling, cold, and normal growth conditions. Chlorophyll content and maximum quantum efficiency of PSII primary photochemistry (Fv/Fm) were reduced in plants grown at chilling stress. The degree of chilling sensitivity of chs1 mutant plants was significantly greater than that of wild-type and chs2 mutants, as measured by chlorophyll fluorescence value and chlorophyll content. MSD1 was expressed during chilling stress in chs mutant and WT plants, while expression of FSD2 and FSD3 SODs in chs mutants was not detected during any of the treatments. Our results suggest that MSD1 expression in chs1-chilled plants responds to chilling, and that the lack of expression of FSD2 and FSD3 genes in chs mutants grown at chilling temperature supports the hypothesis that chloroplasts might be damaged, due to the chs mutation, when they are chilled.

Keywords: Arabidopsis thaliana, chlorophyll content, chs mutant, Fe-SOD, Fv/Fm, Mn-SOD

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