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Front. Plant Sci. | doi: 10.3389/fpls.2018.00953

Overexpression of SSBXoc, a Single-Stranded DNA-Binding Protein from Xanthomonas oryzae pv. oryzicola, Enhances Plant Growth and Disease and Salt Stress Tolerance in Transgenic Nicotiana benthamiana

Yanyan Cao1, Mingtao Yang2,  Wen X. Ma1, Yujing Sun1 and  Gongyou Chen1*
  • 1Shanghai Jiao Tong University, China
  • 2State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, China

We previously reported that SSBXoc, a highly-conserved single-stranded DNA-binding protein from Xanthomonas spp., was secreted through the type III secretion system (T3SS) and functioned as a harpin-like protein to elicit the hypersensitive response (HR) in the non-host plant, tobacco. In this study, we cloned SsbXoc gene from X. oryzae pv. oryzicola (Xoc), , the causal agent of bacterial leaf streak in rice, and transferred it into tobacco Nicotiana benthamiana via Agrobacterium-mediated transformation. The expression of SsbXoc in transgenic tobaccosN. benthamiana enhanced growth of both seedling and adult plants. When inoculated with the harpin Hpa1 or the pathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), the accumulation of reactive oxygen species (ROS) was increased more in SsbXoc transgenic lines than that in wild-type (WT) tobaccoplants. The expression of pathogenesis-related protein genes (PR1a and SGT1), HR marker genes (HIN1 and HSR203J) and the mitogen-activated protein kinase pathway gene, MPK3, was significantly higher in SsbXoc tobacco transgenic lines than in WT after inoculation with Pst DC3000. In addationaddition, SsbXoc transgenic tobacco lines showed the enhanced resistance to the tobacco pathogen P. syringae pvpathogenic bacteria P. s. tabaci and the improved tolerance to salt stress, accompanied by the elevated transcription levels of the defense- and stress-related genes. Taken together, these results indicate that SSBXoc, as a functional harpin, confers overexpression of the SsbXoc gene in N. benthamiana significantly enhanced plant growth and increased tolerance to disease and salt stress via modulating the expression of the related genes in transgenic tobaccosgenes, thus providing an alternative approach for development of plants with improved tolerance against biotic and abiotic stresses.

Keywords: transgenic N. benthamiana, SsbXoc, Plant Growth, hypersensitive response, pathogen resistance, Stress Tolerance

Received: 20 Mar 2018; Accepted: 13 Jun 2018.

Edited by:

Zhengqing Fu, University of South Carolina, Columbia, United States

Reviewed by:

Hai-Lei Wei, Plant Pathology and Plant-Microbe Biology Section, Cornell University, United States
Chang-Sik Oh, Kyung Hee University, South Korea  

Copyright: © 2018 Cao, Yang, Ma, Sun and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Gongyou Chen, Shanghai Jiao Tong University, Shanghai, China, gyouchen@sjtu.edu.cn