Expression of the Grape VqSTS21 Gene in Arabidopsis Confers Resistance to Osmotic Stress and Biotrophic Pathogens but Not Botrytis cinerea.

Li Huang,Xiping Wang,Songlin Zhang,Jinhua Yang,Yuejin Wang,Stacy D Singer,Xiangjing Yin

doi:10.3389/fpls.2016.01379

Abstract

Stilbene synthase (STS) is a key gene in the biosynthesis of various stilbenoids, including resveratrol and its derivative glucosides (such as piceid), that has been shown to contribute to disease resistance in plants. However, the mechanism behind such a role has yet to be elucidated. Furthermore, the function of STS genes in osmotic stress tolerance remains unclear. As such, we sought to elucidate the role of STS genes in the defense against biotic and abiotic stress in the model plant Arabidopsis thaliana. Expression profiling of 31 VqSTS genes from Vitis quinquangularis revealed that VqSTS21 was up-regulated in response to powdery mildew (PM) infection. To provide a deeper understanding of the function of this gene, we cloned the full-length coding sequence of VqSTS21 and overexpressed it in Arabidopsis thaliana via Agrobacterium-mediated transformation. The resulting VqSTS21 Arabidopsis lines produced trans-piceid rather than resveratrol as their main stilbenoid product and exhibited improved disease resistance to PM and Pseudomonas syringae pv. tomato DC3000, but displayed increased susceptibility to Botrytis cinerea. In addition, transgenic Arabidopsis lines were found to confer tolerance to salt and drought stress from seed germination through plant maturity. Intriguingly, qPCR assays of defense-related genes involved in salicylic acid, jasmonic acid, and abscisic acid-induced signaling pathways in these transgenic lines suggested that VqSTS21 plays a role in various phytohormone-related pathways, providing insight into the mechanism behind VqSTS21-mediated resistance to biotic and abiotic stress.

Highlights

Plants are exposed to an environment that is suffused with multiple challenges, including numerous types of biotic and abiotic stresses
Since phytohormone signal transduction pathways, such as those involving salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA), play such an important role in plant stress response, we explored the relationship between STS expression and the expression of genes required in these pathways in order to provide insight into the mechanism behind STS-induced stress resistance
VqSTS21 increased until reaching a peak at 12 hpi, which was earlier than other genes, and declined at subsequent time points (Figure 1)

Summary

Introduction

Plants are exposed to an environment that is suffused with multiple challenges, including numerous types of biotic and abiotic stresses They have evolved the capability to resist such environmental attacks through the development of a series of elaborate and sensitive defense response mechanisms. It has been linked to enhanced plant disease resistance, and exhibits myriad medicinal benefits, such as antiinflammatory, antioxidant and anticancer properties (Aggarwal et al, 2004; Shankar et al, 2007), which has made it the focus of much research The production of this compound relies upon the polyphenol biosynthetic pathway, with the stilbene synthase (STS) enzyme catalyzing the final step in its biosynthesis. This protein shares the same substrates as chalcone synthase (CHS), which is a key enzyme in the biosynthesis of numerous flavonoids, including anthocyanins (Tropf et al, 1994)

Methods

Results

Conclusion