PheASR2, a novel stress-responsive transcription factor from moso bamboo (Phyllostachys edulis), enhances drought tolerance in transgenic rice via increased sensitivity to abscisic acid

Abstract

Abscisic acid, stress and ripening (ASR) transcription factors comprise a small family of proteins that play a key role in stress responses in plants. ASR genes involved in drought tolerance in moso bamboo (Phyllostachys edulis) are largely unknown. In our study, an ASR gene, PheASR2, was isolated and characterized. The expression of PheASR2 was up-regulated under various abiotic stresses, including drought, salt and abscisic acid (ABA). PheASR2 was localized in the nucleus in tobacco cells, and displayed transactivation activity in yeast. Ectopic expression of PheASR2 in rice conferred enhanced tolerance to drought stress, as determined through physiological analyses of germination rate, plant height, water loss and survival rate. The PheASR2-overexpressing transgenic plants showed an increase in reactive oxygen species (ROS), electrolyte leakage and malondialdehyde levels, reduced enzyme (CAT and SOD) activities, and higher expression of genes encoding ROS-scavenging enzymes. Consequently, the transgenic plants exhibited increased tolerance to oxidative stress compared with wild-type plants. Moreover, following ABA treatment, the seed germination rate and plant height of the PheASR2-overexpressing lines were inhibited, and stomatal closure was reduced. The expression of marker genes, including, OsAREB, OsP5CS1, OsLEA, and OsNCED2, was up-regulated in the PheASR2-overexpressing lines when subjected to drought treatment. Together, these results indicate that PheASR2 functions in drought stress tolerance through ABA signaling.