Wheat TaRab7 GTPase Is Part of the Signaling Pathway in Responses to Stripe Rust and Abiotic Stimuli

Furong Liu,Pengfei Bai,Lili Huang,Xiaodong Wang,Zhensheng Kang,Yulin Cheng,Hao Feng,Yinhui Duan,Jun Guo,Zhengguang Zhang

doi:10.1371/journal.pone.0037146

Furong Liu, Pengfei Bai + Show 8 more

Open Access

https://doi.org/10.1371/journal.pone.0037146

Copy DOI

Journal: PloS one	Publication Date: May 22, 2012
Citations: 32	License type: CC BY 4.0

Affiliation: North West Agriculture and Forestry University

Abstract

Small GTP-binding proteins function as regulators of specific intercellular fundamental biological processes. In this study, a small GTP-binding protein Rab7 gene, designated as TaRab7, was identified and characterized from a cDNA library of wheat leaves infected with Puccinia striiformis f. sp. tritici (Pst) the wheat stripe rust pathogen. The gene was predicted to encode a protein of 206 amino acids, with a molecular mass of 23.13 KDa and an isoeletric point (pI) of 5.13. Further analysis revealed the presence of a conserved signature that is characteristic of Rab7, and phylogenetic analysis demonstrated that TaRab7 has the highest similarity to a small GTP binding protein gene (BdRab7-like) from Brachypodium distachyon. Quantitative real-time PCR assays revealed that the expression of TaRab7 was higher in the early stage of the incompatible interactions between wheat and Pst than in the compatible interaction, and the transcription level of TaRab7 was also highly induced by environmental stress stimuli. Furthermore, knocking down TaRab7 expression by virus induced gene silencing enhanced the susceptibility of wheat cv. Suwon 11 to an avirulent race CYR23. These results imply that TaRab7 plays an important role in the early stage of wheat-stripe rust fungus interaction and in stress tolerance.

Highlights

Small GTP-binding proteins are monomeric G proteins with molecular masses of 20–40 kDa
Sequence analysis indicated that TaRab7 includes a complete 618 bp open-reading frame (ORF) which encodes a putative protein composed of 206 amino acids
The amino acid sequence alignment demonstrated that TaRab7 has the conserved guanine nucleotide binding motifs and domains of small G proteins from animals and plants, which are important for interaction with its regulators and effectors

Summary

Introduction

Small GTP-binding proteins are monomeric G proteins with molecular masses of 20–40 kDa. Because Rabs do not have high intrinsic guanine nucleotide exchange or hydrolytic activities, they are regulated by other proteins, such as guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). In their GDP-bound state, Rabs are typically soluble and bound to guanine nucleotide dissociation inhibitor (GDI). A GEF converts Rab to its GTP-bound, active conformation, allowing it to interact with its downstream effectors. The homotypic fusion and vacuole protein sorting (HOPs) may play dual roles as upstream GEF and downstream tethering effector of Rab to facilitate endosomal membrane fusion [14]

Methods

Results

Conclusion