Oryza sativa protein phosphatase 1a (OsPP1a) involved in salt stress tolerance in transgenic rice

Abstract

Serine/threonine protein phosphatases (PPs) can be grouped into PP1 and PP2 based on enzymological criteria using specific inhibitors and activators. PP2 receives abscisic acid as signal and negative regulation of tolerance of high salt, drought, and cold stresses, yet the role of PP1 in stress tolerance remains unknown. The objective of this study was to transfer OsPP1a cDNA to rice via Agrobacterium tumefaciens strain EHA105 to assess the mechanisms by which it can confer tolerance to salt treatment. All OsPP1a transcript levels except for OsPP1a-4 detected in transgenic lines were significantly higher than in non-transgenic (NT) plants. Transgenic plants overexpressing OsPP1a showed enhanced tolerance to high salt treatment, SnRK1A, and two stress-responsive genes, OsNAC5 and OsNAC6, which were up-regulated in transgenic OsPP1a-2, OsPP1a-3, and OsPP1a-6 lines. The gene expression profiles of lines OsPP1a-2, -3, and -6 were well-matched with the data for ascorbate peroxidase (APX) and superoxide dismutase (SOD) activity, scavenging the DPPH radical, and malondialdehyde content in NT and transgenic plants under salt stress treatment. In addition, transgenic rice plants also exhibited higher survival rates and plant heights, fewer oxidative injuries, and grew faster than NT plants exposed to salt treatment. Thus, the overexpression of OsPP1a in rice may be useful for enhancing tolerance in high-salt areas.