HbWRKY27, a group IIe WRKY transcription factor, positively regulates HbFPS1 expression in Hevea brasiliensis

Long Qu,Ying Wang,Jia-Hong Zhu,Li-Yan Yin,Shi-Qing Peng,Hui-Liang Li,Dong Guo

doi:10.1038/s41598-020-77805-5

Long Qu, Ying Wang + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-77805-5

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Abstract

Farnesyl pyrophosphate synthase (FPS) is a key enzyme that catalyzes the formation of farnesyl pyrophosphate, the main initiator for rubber chain initiation in Hevea brasiliensis Muell. Arg. The transcriptional regulatory mechanisms of the FPS gene still not well understood. Here, a WRKY transcription factor designated HbWRKY27 was obtained by screening the latex cDNA library applied the HbFPS1 promoter as bait. HbWRKY27 interacted with the HbFPS1 promoter was further identified by individual Y1H and EMSA assays. HbWRKY27 belongs to group IIe WRKY subfamily which contains a typical WRKY domain and C-X5-CX23-HXH motif. HbWRKY27 was localized to the nucleus. HbWRKY27 predominantly accumulated in latex. HbWRKY27 was up-regulated in latex by ethrel, salicylic acid, abscisic acid, and methyl jasmonate treatment. Transient expression of HbWRKY27 led to increasing the activity of the HbFPS1 promoter in tobacco plant, suggesting that HbWRKY27 positively regulates the HbFPS1 expression. Taken together, an upstream transcription factor of the key natural rubber biosynthesis gene HbFPS1 was identified and this study will provide novel transcriptional regulatory mechanisms of the FPS gene in Hevea brasiliensis.

Highlights

To understand the transcriptional regulatory of HbFPS1, the HbFPS1 promoter was employed as the bait to screen transcription factors that interact with the HbFPS1 promoter from Y1H-based latex cDNA library
One cDNA encoding WRKY transcription factor, named HbWRKY27 according to its homologs in Genbank, was obtained
To further determine that HbWRKY27 physically bound with the HbFPS1 promoter, Electrophoretic mobility shift assay (EMSA) was used to confirm the binding affinity of HbWRKY27 to the HbFPS1 promoter

Summary

Introduction

The valuable of rubber tree as a sole commercial source rubber-producing plant led to enormous interest in understanding the natural rubber biosynthesis and regulation in rubber tree. Natural rubber cis 1, 4-polyisoprene biopolymer, is mainly synthesized by the mevalonate pathway that produces isopentenyl pyrophosphate (IPP) as the precursor and building rubber chain s keleton[1]. Farnesyl pyrophosphate (FPP) may be the main initiator during natural rubber biosynthesis in rubber tree[5,6,7]. The rubber tree FPS genes (named HbFPS1, HbFPS2, and HbFPS3) have been cloned and characterized[11]. The expression of HbFPS1 exhibits a positive correlation with natural rubber b iosynthesis[11,12]. Two MYB transcription factors (HblMYB19 and HblMYB44) are identified to up-regulate the expression of HbFPS113. A WRKY transcription factor (designated as HbWRKY27) bound the HbFPS1 promoter and positively regulate HbFPS1 expression, demonstrating that HbWRKY27 might a positive transcription regulator of HbFPS1

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