Abstract
MYB-type transcription factors (TFs) play essential roles in plant growth, development and respond to environmental stresses. Role of MYB-related TFs of rice in drought stress tolerance is not well documented. Here, we report the isolation and characterization of a novel MYB-related TF, OsMYB48-1, of rice. Expression of OsMYB48-1 was strongly induced by polyethylene glycol (PEG), abscisic acid (ABA), H2O2, and dehydration, while being slightly induced by high salinity and cold treatment. The OsMYB48-1 protein was localized in the nucleus with transactivation activity at the C terminus. Overexpression of OsMYB48-1 in rice significantly improved tolerance to simulated drought and salinity stresses caused by mannitol, PEG, and NaCl, respectively, and drought stress was caused by drying the soil. In contrast to wild type plants, the overexpression lines exhibited reduced rate of water loss, lower malondialdehyde (MDA) content and higher proline content under stress conditions. Moreover, overexpression plants were hypersensitive to ABA at both germination and post-germination stages and accumulated more endogenous ABA under drought stress conditions. Further studies demonstrated that overexpression of OsMYB48-1 could regulate the expression of some ABA biosynthesis genes (OsNCED4, OsNCED5), early signaling genes (OsPP2C68, OSRK1) and late responsive genes (RAB21, OsLEA3, RAB16C and RAB16D) under drought stress conditions. Collectively, these results suggested that OsMYB48-1 functions as a novel MYB-related TF which plays a positive role in drought and salinity tolerance by regulating stress-induced ABA synthesis.
Highlights
Crop plants are frequently exposed to variable abiotic stresses
Three-week-old seedlings were treated with stress including dehydration stress, high osmotic pressure using 20% (w/v) polyethylene glycol (PEG) 6000 solution, salinity stress using 150 mM NaCl solution, cold exposure at 4uC, oxidative stress using 1 mM H2O2 solution, and hormone treatment using 100 mM Abscisic acid (ABA) solution followed by sampling in a pre-determined time manner
The identification of some MYB transcription factors (TFs) in rice and their roles in abiotic stress response has been reported recently [20,22,34], our results indicated that OsMYB48-1 to have unique features as compared to other MYB members in rice
Summary
Crop plants are frequently exposed to variable abiotic stresses. ABA content increases dramatically when plants are exposed to abiotic stresses such as drought and salinity that triggers the expression of many genes encoding various proteins important for biochemical and physiological processes [3,4,5]. These proteins help plants be tolerant to the stresses that includes late embryogenesis abundant (LEA) proteins, enzymes involved in osmo-protectant synthesis, protection proteins for plants from oxidative damage, and signaling proteins, such as the transcription factors (TFs) [2]
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