The Study of Some Morphological, Physiological and Molecular Parameters in the Chs Mutants of Arabidopsis thaliana

Many plants of tropical and subtropical areas are severely damaged when exposed to chilling temperatures between 2 and 15°C. Arabidopsis thaliana is chilling tolerant and, therefore provides an alternative model plant system for the identification of chilling tolerance traits. To determine whether the expression of Cu/Zn-superoxide dismutase 2 (CSD2) would increase superoxide-scavenging capacity and thereby improve the survival rate of chilling sensitive (chs) mutants of Arabidopsis, four chs mutant (chs1-1, chs1-2, chs2-1 and chs2-2) and wild-type plants were grown under low (chilling at 13 °C and 4 °C) and normal growth (23 °C) temperatures. The expression of CSD2 was not detected during cold stress treatments, while the wild plants showed the expression of CSD2 under cold stress. The increase of antioxidant enzymes activities (POX and SOD) showed the role of these enzymes in the protection of the chs mutants under chilling treatment, also the increase in polyphenol oxidase activity shows the role of that in the emergence of chlorosis phenotype. The lack of expression of CSD2 gene in chs mutants grown at chilling temperature would support the hypothesis that the expression of these genes was affected due to mutation in CHS genes, when they are chilled.