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Plant Mol Biol (2014) 84:1936 DOI 10.1007/s11103-013-0115-3
OsbZIP71, a bZIP transcription factor, confers salinity and drought tolerance in rice
Citao Liu Bigang Mao Shujun Ou
Wei Wang Linchuan Liu Yanbin Wu
Chengcai Chu Xiping Wang
Received: 21 April 2013 / Accepted: 24 July 2013 / Published online: 6 August 2013 Springer Science+Business Media Dordrecht 2013
Abstract The bZIP transcription factor (TF) family plays an important role in the abscisic acid (ABA) signaling pathway of abiotic stress in plants. We here report the cloning and characterization of OsbZIP71, which encodes a rice bZIP TF. Functional analysis showed that OsbZIP71 is a nuclear-localized protein that specically binds to the G-box motif, but has no transcriptional activity both in yeast and rice protoplasts. In yeast two-hybrid assays, OsbZIP71 can form both homodimers and heterodimers with Group C members of the bZIP gene family. Expression of OsbZIP71 was strongly induced by drought, polyethylene glycol (PEG), and ABA treatments, but repressed by salt treatment. OsbZIP71 overexpressing (p35S::Osb-ZIP71) rice signicantly improved tolerance to drought, salt and PEG osmotic stresses. In contrast, RNAi knockdown transgenic lines were much more sensitive to salt,
PEG osmotic stresses, and also ABA treatment. Inducible expression (RD29A::OsbZIP71) lines were signicantly improved their tolerance to PEG osmotic stresses, but hypersensitivity to salt, and insensitivity to ABA. Real-time PCR analysis revealed that the abiotic stress-related genes, OsVHA-B, OsNHX1, COR413-TM1, and OsMyb4, were up-regulated in overexpressing lines, while these same genes were down-regulated in RNAi lines. Chromatin immunoprecipitation analysis conrmed that OsbZIP71 directly binds the promoters of OsNHX1 and COR413-TM1 in vivo. These results suggest that OsbZIP71 may play an important role in ABA-mediated drought and salt tolerance in rice.
Keywords Rice (Oryza sativa L.) bZIP
transcription factor OsbZIP71 Abiotic stress
tolerance ABA sensitivity
AbbreviationsbZIP Basic leucine zipperOsCAT Rice catalase isozyme AOsVHA-B Rice vacuolar-ATPase subunit B OsNHX Rice Na?/H? antiporterOsCLC1 Rice Cl-channelOsHKT Rice high-afnity potassium transporter OsPP15 Rice protein phosphatase 15 COR413-TM1 Cold acclimation protein 413-TM1
Introduction
To survive under abiotic stresses, plants have evolved complex signaling pathways, which are generically comprised of receptors, secondary messengers, phytohormones,
Citao Liu, Bigang Mao and Shujun Ou have contributed equally to this work.
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s11103-013-0115-3
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