Molecular Cloning and the Expression Pattern of a Phospholipid Hydroperoxide Glutathione Peroxidase in Kalidium foliatum under NaCl Treatment

Abstract

The halophyte Kalidium foliatum (Pall.) Moq. exhibits strong tolerance to salinity. Salt stress leads to reactive oxygen species (ROS) production, and high contents of ROS are harmful to plants. The phospholipid hydroperoxide glutathione peroxidase (PHGPx) responds positively to damage induced by ROS. To understand the mechanism of tolerance to salt stress in halophytes, a PHGPx gene of K. foliatum was cloned, and its expression pattern was analysed under salt treatment. Treatments of whole plants were carried out with 0, 150, 200, 250, 300, 350 or 400 mM sodium chloride for 72 h. The extraction of total RNA from 4‑month-old seedlings was conducted using the leaves of both treated and untreated plants. The full-length cDNA of KfPHGPx was cloned with reverse transcription PCR (RT-PCR), the KfPHGPx expression patterns were analysed using semi-quantitative RT-PCR and real-time PCR, and the activities of phospholipid hydroperoxide glutathione peroxidase enzyme in K. foliatum were examined. The full-length cDNA clone encoding the full-length sequence consisted of 714 bp of nucleotides and included an open reading frame (ORF) that encoded a polypeptide of 237 amino acids. The deduced amino acid sequence of the KfPHGPx gene has significant similarity with Spinacia oleracea (XP_021837527.1) and Sesuvium portulacastrum (ADE07246.1). The semi-quantitative RT-PCR and real-time PCR analyse showed that KfPHGPx expression can be markedly induced by moderate salt treatment.