Overexpression of a Stress-Responsive NAC Transcription Factor Gene ONAC022 Improves Drought and Salt Tolerance in Rice

Abstract

The NAC transcription factors play critical roles in regulating stress responses in plants. However, the functions for many of the NAC family members in rice are yet to be identified. In the present study, a novel stress-responsive rice NAC gene, ONAC022, was identified. Expression of ONAC022 was induced by drought, high salinity, and abscisic acid (ABA). The ONAC022 protein was found to bind specifically to a canonical NAC recognition cis-element sequence and showed transactivation activity at its C-terminus in yeast. The ONAC022 protein was localized to nucleus when transiently expressed in Nicotiana benthamiana. Three independent transgenic rice lines with overexpression of ONAC022 were generated and used to explore the function of ONAC022 in drought and salt stress tolerance. Under drought stress condition in greenhouse, soil-grown ONAC022-overexpressing (N22oe) transgenic rice plants showed an increased drought tolerance, leading to higher survival ratios and better growth than wild-type (WT) plants. When grown hydroponically in Hogland solution supplemented with 150 mM NaCl, the N22oe plants displayed an enhanced salt tolerance and accumulated less Na+ in roots and shoots as compared to WT plants. Under drought stress condition, the N22oe plants exhibited decreased rates of water loss and transpiration, reduced percentage of open stomata and increased contents of proline and soluble sugars. However, the N22oe lines showed increased sensitivity to exogenous ABA at seed germination and seedling growth stages but contained higher level of endogenous ABA. Expression of some ABA biosynthetic genes (OsNCEDs and OsPSY), signaling and regulatory genes (OsPP2C02, OsPP2C49, OsPP2C68, OsbZIP23, OsAP37, OsDREB2a, and OsMYB2), and late stress-responsive genes (OsRAB21, OsLEA3, and OsP5CS1) was upregulated in N22oe plants. Our data demonstrate that ONAC022 functions as a stress-responsive NAC with transcriptional activator activity and plays a positive role in drought and salt stress tolerance through modulating an ABA-mediated pathway.

Thiourea priming enhances salt tolerance through co-ordinated regulation of microRNAs and hormones in Brassica juncea

“…AP2 like transcription factor (targeted through bra-miR172c-3p) codes for a DNA binding protein and regulate G1-S transitions in shoot apical meristem60. NAC transcription factor (targeted through bra-miR164b-5p), is a DNA binding protein which regulate stress related gene expression through ABA dependent pathway61. On the contrary, targets showing upregulated expression in NaCl treatment were mainly effector genes.…”

Overexpression of OsTF1L, a rice HD‐Zip transcription factor, promotes lignin biosynthesis and stomatal closure that improves drought tolerance

“…The reduced culm number 1 ( rcn1 ) mutant encoding OsABCG5 shows rapid water loss more than the wild‐type plants by deficiency of stomatal closure during drought stress (Matsuda et al ., ). The rice NAC gene, ONAC022 , was also identified as a positive role in drought tolerance through modulating a stomatal closure (Hong et al ., ). The up‐regulation of stomatal movement genes is consistent with our observation that OsTF1L OX plants showed high ratio of the stomatal closure under drought conditions.…”

“…Regulation of stomatal movement in this regard has been an active research area for drought tolerance. For example, overexpression of OsASR5 , ONAC022 , AtMYB61 , BplMYB46 and PtoMYB170 significantly enhanced drought tolerance in plants by regulation of stomatal closure under drought stress conditions (Guo et al ., ; Hong et al ., ; Li et al ., ; Romano et al ., ; Xu et al ., ). Interestingly, overexpression of AtMYB61 , BplMYB46 and PtoMYB170 also increased lignin biosynthesis.…”

Transcriptomic Changes of Drought-Tolerant and Sensitive Banana Cultivars Exposed to Drought Stress

“…The main TFs in this network include MYB, bHLH, bZIP, ERF, NAC, and WRKY etc. Moreover, overexpression of some of drought stress responsive TFs have been shown to confer drought tolerance (Hong et al, 2016; Yu et al, 2016). At the cellular level, plants respond to drought with changes in gene expression which lead to several other modifications at transcriptional and translational modifications, accumulation of osmo-protectants, enhanced water uptake (e.g., Aquaporin), reduction in transpirational water loss, strong antioxidants, heat shock proteins (hsps) and other stress tolerance proteins like dehydrin, metabolite abundances etc.…”