Tolerance analysis of chloroplast OsCu/Zn-SOD overexpressing rice under NaCl and NaHCO3 stress

• DOI: 10.1371/journal.pone.0186052
• Publication Date: 2017-10-11T13:43:35Z
• Authors: Qingjie Guan; Xu Liao; Mingliang He; Xiufeng Li; Zhenyu Wang; Haiyan Ma; Song Yu; Shenkui Liu
• Keywords: 0301 basic medicine; Chloroplasts; Science; Genetic Vectors; Green Fluorescent Proteins; Sodium Chloride; Real-Time Polymerase Chain Reaction; 03 medical and health sciences; Superoxide Dismutase-1; Gene Expression Regulation, Plant; Stress, Physiological; Amino Acid Sequence; Cloning, Molecular; Phylogeny; 2. Zero hunger; Q; R; Oryza; Plants, Genetically Modified; Adaptation, Physiological; Sodium Bicarbonate; Seedlings; Medicine; Reactive Oxygen Species; Sequence Alignment; Research Article; Subcellular Fractions

The 636-bp-long cDNA sequence of OsCu/Zn-SOD (AK059841) was cloned from Oryza sativa var. Longjing11 via reverse transcription polymerase chain reaction (RT-PCR). The encoded protein comprised of 211 amino acids is highly homologous to Cu/Zn-SOD proteins from tuscacera rice and millet. Quantitative RT-PCR revealed that in rice, the level of OsCu/Zn-SOD gene expression was lowest in roots and was highest in petals and during the S5 leaf stage. Moreover, the expression level of OsCu/Zn-SOD gene expression decreased during the L5 leaf stage to maturity. The level of OsCu/Zn-SOD gene expression, however, was increased under saline-sodic stress and NaHCO3 stress. Germination tests under 125, 150, and 175 mM NaCl revealed that OsCu/Zn-SOD-overexpressing lines performed better than the non-transgenic (NT) Longjing11 lines in terms of germination rate and height. Subjecting seedlings to NaHCO3 and water stress revealed that OsCu/Zn-SOD-overexpressing lines performed better than NT in terms of SOD activity, fresh weight, root length, and height. Under simulated NaHCO3 stress, OsCu/Zn-SOD-overexpressing lines performed better than NT in terms of survival rate (25.19% > 6.67%) and yield traits (average grain weight 20.6 > 18.15 g). This study showed that OsCu/Zn-SOD gene overexpression increases the detoxification capacity of reactive oxygen species in O. sativa and reduces salt-induced oxidative damage. We also revealed the regulatory mechanism of OsCu/Zn-SOD enzyme in saline-sodic stress resistance in O. sativa. Moreover, we provided an experimental foundation for studying the mechanism of OsCu/Zn-SOD enzymes in the chloroplast.