Rice NAC transcription factor ONAC066 functions as a positive regulator of drought and oxidative stress response

Xi Yuan,Hui Wang,Fengming Song,Jiating Cai,Yan Bi,Dayong Li

doi:10.1186/s12870-019-1883-y

Xi Yuan, Hui Wang + Show 4 more

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https://doi.org/10.1186/s12870-019-1883-y

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Abstract

BackgroundNAC (NAM, ATAF and CUC) transcriptional factors constitute a large family with more than 150 members in rice and several members of this family have been demonstrated to play crucial roles in rice abiotic stress response. In the present study, we report the function of a novel stress-responsive NAC gene, ONAC066, in rice drought and oxidative stress tolerance.ResultsONAC066 was localized in nuclei of cells when transiently expressed in Nicotiana benthamiana and is a transcription activator with the binding ability to NAC recognition sequence (NACRS) and AtJUB1 binding site (JBS). Expression of ONAC066 was significantly induced by PEG, NaCl, H2O2 and abscisic acid (ABA). Overexpression of ONAC066 in transgenic rice improved drought and oxidative stress tolerance and increased ABA sensitivity, accompanied with decreased rate of water loss, increased contents of proline and soluble sugars, decreased accumulation of reactive oxygen species (ROS) and upregulated expression of stress-related genes under drought stress condition. By contrast, RNAi-mediated suppression of ONAC066 attenuated drought and oxidative stress tolerance and decreased ABA sensitivity, accompanied with increased rate of water loss, decreased contents of proline and soluble sugars, elevated accumulation of ROS and downregulated expression of stress-related genes under drought stress condition. Furthermore, yeast one hybrid and chromatin immunoprecipitation-PCR analyses revealed that ONAC066 bound directly to a JBS-like cis-elements in OsDREB2A promoter and activated the transcription of OsDREB2A.ConclusionONAC066 is a nucleus-localized transcription activator that can respond to multiple abiotic stress factors. Functional analyses using overexpression and RNAi-mediated suppression transgenic lines demonstrate that ONAC066 is a positive regulator of drought and oxidative stress tolerance in rice.

Highlights

NAC (NAM, ATAF and CUC) transcriptional factors constitute a large family with more than 150 members in rice and several members of this family have been demonstrated to play crucial roles in rice abiotic stress response
These results indicate that ONAC066 has a transactivation activity and the region of 265–362 aa at Cterminus is critical for the transactivation activity
We further explored whether modification of ONAC066 affected the tolerance of transgenic rice plants to methyl viologen (MV), by comparing growth phenotype of and chlorophyll content in ONAC066-OE and ONAC066-RNA interference (RNAi) seedlings grown on 1/2 Murashige and Skoog (MS) medium supplemented with MV to those of wild type (WT) seedlings

Summary

Introduction

NAC (NAM, ATAF and CUC) transcriptional factors constitute a large family with more than 150 members in rice and several members of this family have been demonstrated to play crucial roles in rice abiotic stress response. We report the function of a novel stress-responsive NAC gene, ONAC066, in rice drought and oxidative stress tolerance. Recent extensive functional studies have demonstrated that NAC TFs play important roles in regulating biotic and abiotic stress responses in both model and crop plants [8, 12, 18, 19]. Functional studies have identified at least 9 rice ONAC genes that play important roles in abiotic stress tolerance and these abiotic stress-related includes ONAC002 (SANC1/OsNAC9), ONAC048 (SNAC2/OsNAC6), ONAC009 (OsNAC5), ONAC122 (OsNAC10), ONAC045, ONAC058 (OsNAP), ONAC022, ONAC095 and ONAC003 (SNAC3) [22,23,24,25,26,27,28,29,30,31,32,33,34]. Transgenic rice lines overexpressing some of the stress-related NAC TFs exhibited significant improvement of abiotic stress tolerance under severe stress conditions without any adverse effect on yield or even with yield increase [22, 26, 27, 29, 30], providing a promising potential for application of these stress-related NAC TFs in improvement of abiotic stress tolerance in crops [36, 37]

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