Virus-Induced Gene Silencing-Based Functional Analyses Revealed the Involvement of Several Putative Trehalose-6-Phosphate Synthase/Phosphatase Genes in Disease Resistance against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000 in Tomato.

Fengming Song,Yi Dai,Zhongye Cao,Shixia Liu,Dayong Li,Lihong Huang,Lei Huang,Huijuan Zhang,Yongbo Hong,Limei Tian

doi:10.3389/fpls.2016.01176

Fengming Song, Yi Dai + Show 8 more

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https://doi.org/10.3389/fpls.2016.01176

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Abstract

Trehalose and its metabolism have been demonstrated to play important roles in control of plant growth, development, and stress responses. However, direct genetic evidence supporting the functions of trehalose and its metabolism in defense response against pathogens is lacking. In the present study, genome-wide characterization of putative trehalose-related genes identified 11 SlTPSs for trehalose-6-phosphate synthase, 8 SlTPPs for trehalose-6-phosphate phosphatase and one SlTRE1 for trehalase in tomato genome. Nine SlTPSs, 4 SlTPPs, and SlTRE1 were selected for functional analyses to explore their involvement in tomato disease resistance. Some selected SlTPSs, SlTPPs, and SlTRE1 responded with distinct expression induction patterns to Botrytis cinerea and Pseudomonas syringae pv. tomato (Pst) DC3000 as well as to defense signaling hormones (e.g., salicylic acid, jasmonic acid, and a precursor of ethylene). Virus-induced gene silencing-mediated silencing of SlTPS3, SlTPS4, or SlTPS7 led to deregulation of ROS accumulation and attenuated the expression of defense-related genes upon pathogen infection and thus deteriorated the resistance against B. cinerea or Pst DC3000. By contrast, silencing of SlTPS5 or SlTPP2 led to an increased expression of the defense-related genes upon pathogen infection and conferred an increased resistance against Pst DC3000. Silencing of SlTPS3, SlTPS4, SlTPS5, SlTPS7, or SlTPP2 affected trehalose level in tomato plants with or without infection of B. cinerea or Pst DC3000. These results demonstrate that SlTPS3, SlTPS4, SlTPS5, SlTPS7, and SlTPP2 play roles in resistance against B. cinerea and Pst DC3000, implying the importance of trehalose and tis metabolism in regulation of defense response against pathogens in tomato.

Highlights

Trehalose (α-D-glucopyranosyl α-D-glucopyranoside) is a ubiquitously distributed non-reducing disaccharide (Elbein et al, 2003)
By Blastp searches against the tomato genome database using the characterized Arabidopsis AtTPSs, AtTPPs, and AtTRE1 as queries, we identified 11, 8, and 1 loci in tomato genome that were predicted to encode trehalose-6-phosphate synthase (TPS), T-6-phosphate phosphatase (TPP), and TRE and designated as SlTPS1-11, SlTPP1-8, and SlTRE1, respectively (Table 1), based on their chromosomal locations
We examined the silencing specificity of SlTPS3, SlTPS4, SlTPS5, SlTPS7, and SlTPP2, whose silencing led to altered resistance to B. cinerea or Pst DC3000, by comparing the transcript levels of the target gene and its relative family members in TRV-SlTPS3, TRV-SlTPS4, TRV-SlTPS5, TRV-SlTPS7, and TRV-SlTPP2-infiltrated plants

Summary

Introduction

Trehalose (α-D-glucopyranosyl α-D-glucopyranoside) is a ubiquitously distributed non-reducing disaccharide (Elbein et al, 2003). Group I TPSs contain both TPS and TPP domains and the Arabidopsis AtTPS1, AtTPS2, and AtTPS4 are active enzymes (Blazquez et al, 1998; Vandesteene et al, 2010; Delorge et al, 2015). Group II TPSs contain both TPS and TPP domains and most of them harbor conserved phosphatase domains (Vandesteene et al, 2010; Zhang et al, 2011). Whereas most of the Arabidopsis Class II TPSs are not active enzymes (Ramon et al, 2009), AtTPS6 and AtTPS11 were found to possess TPS or TPP activity (Chary et al, 2008; Singh et al, 2011). Plant TPPs contain unique TPP domains with conserved phosphatase domains and all of them possess TPP activities (Shima et al, 2007)

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