HyPRP1 Gene Suppressed by Multiple Stresses Plays a Negative Role in Abiotic Stress Tolerance in Tomato

Jinhua Li,Zhibiao Ye,Bo Ouyang,Changxian Yang,Taotao Wang,Wei Sima,Junhong Zhang,Zhidan Luo,Hanxia Li

doi:10.3389/fpls.2016.00967

Abstract

Many hybrid proline-rich protein (HyPRP) genes respond to biotic and abiotic stresses in plants, but little is known about their roles other than as putative cell-wall structural proteins. A HyPRP1 gene encodes a protein with proline-rich domain, and an eight-cysteine motif was identified from our previous microarray experiments on drought-tolerant tomato. In this study, the expression of the HyPRP1 gene in tomato was suppressed under various abiotic stresses, such as drought, high salinity, cold, heat, and oxidative stress. Transgenic functional analysis showed no obvious changes in phenotypes, but enhanced tolerance to various abiotic stresses (e.g., oxidative stress, dehydration, and salinity) was observed in RNAi transgenic plants. Interestingly, several SO2 detoxification-related enzymes, including sulfite oxidase, ferredoxins (Fds), and methionine sulfoxide reductase A (Msr A), were revealed in HyPRP1-interacting proteins identified by Yeast Two-Hybrid screening. More sulfates and transcripts of Msr A and Fds were accumulated in HyPRP1 knockdown lines when wild-type plants were exposed to SO2 gas. Our findings illustrate that the tomato HyPRP1 is a negative regulator of salt and oxidative stresses and is probably involved in sulfite metabolism.

Highlights

Hybrid proline-rich proteins (HyPRPs) comprise a dynamically evolving protein family unique to seed plants (Dvorakova et al, 2007) and are initially defined as proteins that respond to wounding (Chen and Varner, 1985)
The cells that expressed SpHyPRP1 only showed slightly reduced oxidative tolerance (Figures 1B,C). These results indicated that HyPRP1 protein plays a negative role in scavenging reactive oxygen species (ROS) in E. coli and exhibits different effects based on the introduction of SlHyPRP1 or SpHyPRP1
SpHyPRP1 and SlHyPRP1 showed different ROS-scavenging ability in E. coli cells, which should be attributed to their individual amino acid sequences and protein structures

Summary

Introduction

Hybrid proline-rich proteins (HyPRPs) comprise a dynamically evolving protein family unique to seed plants (Dvorakova et al, 2007) and are initially defined as proteins that respond to wounding (Chen and Varner, 1985). HyPRPs have been widely reported to respond to biotic and abiotic stresses. A heterologously expressed Arabidopsis HyPRP gene EARLI1 can improve the survival of yeast cells in freezing conditions (Zhang and Schlappi, 2007); A pigeon pea HyPRP gene (CcHyPRP) expressed in yeast and Arabidopsis affords multiple abiotic stress tolerance (Priyanka et al, 2010). HyPRP1 Negatively Regulates Stress Tolerance the EARLI1 in Arabidopsis was found that it plays an auxiliary role for low temperature and salt stress protection responses (Xu et al, 2011), and the overexpression of Medicago falcata HyPRP (MfHyPRP) in tobacco increased its tolerance to freezing, chilling, osmotic stress, and methyl viologen (MV)-induced oxidative stress (Tan et al, 2013). Little is known about the functional roles of HyPRP and its molecular mechanism in abiotic stresses in tomato

Methods

Results

Conclusion