Overexpression of BoNAC019, a NAC transcription factor from Brassica oleracea, negatively regulates the dehydration response and anthocyanin biosynthesis in Arabidopsis

Jinfang Wang,Shuxin Ren,Xingsheng Li,Sijia Qin,Gongle Wang,Yunyun Cao,Xiaowei Yuan,Yang-Dong Guo,Lun Liu,Chuandong Qi,Weiran Lian,Xiaoyun Wang

doi:10.1038/s41598-018-31690-1

Jinfang Wang, Shuxin Ren + Show 10 more

Open Access

https://doi.org/10.1038/s41598-018-31690-1

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Abstract

NACs are one of the largest transcription factor families in plants and are involved in the response to abiotic stress. BoNAC019, a homologue of AtNAC019, was isolated from cabbage (Brassica oleracea). BoNAC019 was localized in the nucleus and functioned as a transcriptional activator. The expression of BoNAC019 was induced by dehydration, salt, abscisic acid (ABA), and H2O2 treatments. BoNAC019 overexpressing plants were generated to explore the function of BoNAC019 in response to drought stress. Overexpression (OE) of BoNAC019 reduced drought tolerance with lower survival rate, higher water loss rate, lower proline content and ABA content. The seed germination and root length assays of BoNAC019-OE plants showed decreased sensitivity to ABA. Under drought condition, antioxidant enzymes and anthocyanin content decreased in BoNAC019 -OE plants, resulting in the accumulation of more reactive oxygen species (ROS), which cause damage to plants. Several stress-responsive genes, antioxidant enzymatic genes, anthocyanin biosynthetic genes and ABA signaling genes were down-regulated under drought condition while the ABA catabolism genes were induced in BoNAC019-OE plants under both normal and drought conditions. Our results demonstrated that BoNAC019 might participated in regulating drought tolerance by inducing ABA catabolism genes and decreasing ABA content.

Highlights

NACs are one of the largest transcription factor families in plants, it has been reported in many species
Compared with the WT plants, anthocyanin content was much lower in BoNAC019-OE plants, and the expressions of anthocyanin biosynthetic genes decreased in BoNAC019-OE plants. These results showed that BoNAC019 negatively regulated the tolerance to drought stress and anthocyanin biosynthesis
The relative LUC activities of Arabidopsis protoplasts transformed with GAL4BD-BoNAC019, GAL4BD-BoNAC019-C were significantly higher than negative control and GAL4BD-BoNAC019-N (Fig. 1C,D)

Summary

Introduction

NACs are one of the largest transcription factor families in plants, it has been reported in many species. AtNAC019, AtNAC055, and AtNAC072 were stress-responsive NAC genes, the expressions of these genes were induced by drought treatment. Overexpressing AtNAC019, AtNAC055, and AtNAC072 improved drought tolerance and up-regulated the expression of ERD1 (early responsive to drought 1)[16,18]. Overexpressing OsNAC1 enhanced drought tolerance in transgenic rice, and lots of stress-responsive genes were induced in OsNAC1 overexpressing plants. Overexpressing OsNAC3 in rice showed improved tolerance to heat and drought stresses in transgenic plants. Overexpressing RhNAC3 improved drought tolerance in transgenic Arabidopsis, and many genes respond to stress were induced in overexpressing lines[20]. For ABA signaling, the receptors named PYRs (pyrabactin resistances) were reported in 2009 Overexpressing these genes have been verified to improve drought stress resistance in Arabidopsis[25,26]. Enzymatic antioxidants and non-enzymatic antioxidants, including ascorbate, glutathione (GSH), carotenoids, tocopherols, and flavonoids are defense systems for scavenging ROS in plants[30,31]

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