Two TGA Transcription Factor Members from Hyper-Susceptible Soybean Exhibiting Significant Basal Resistance to Soybean mosaic virus.

Hua Jiang,Junyi Gai,Shengyu Gu,Kai Li

doi:10.3390/ijms222111329

Hua Jiang, Junyi Gai + Show 2 more

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https://doi.org/10.3390/ijms222111329

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Abstract

TGA transcription factors (TFs) exhibit basal resistance in Arabidopsis, but susceptibility to a pathogen attack in tomatoes; however, their roles in soybean (Glycine max) to Soybean mosaic virus (SMV) are unknown. In this study, 27 TGA genes were isolated from a SMV hyper-susceptible soybean NN1138-2, designated GmTGA1~GmTGA27, which were clustered into seven phylogenetic groups. The expression profiles of GmTGAs showed that the highly expressed genes were mainly in Groups I, II, and VII under non-induction conditions, while out of the 27 GmTGAs, 19 responded to SMV-induction. Interestingly, in further transient N. benthamiana-SMV pathosystem assay, all the 19 GmTGAs overexpressed did not promote SMV infection in inoculated leaves, but they exhibited basal resistance except one without function. Among the 18 functional ones, GmTGA8 and GmTGA19, with similar motif distribution, nuclear localization sequence and interaction proteins, showed a rapid response to SMV infection and performed better than the others in inhibiting SMV multiplication. This finding suggested that GmTGA TFs may support basal resistance to SMV even from a hyper-susceptible source. What the mechanism of the genes (GmTGA8, GmTGA19, etc.) with basal resistance to SMV is and what their potential for the future improvement of resistance to SMV in soybeans is, are to be explored.

Highlights

Plants show a resistance or susceptibility response in facing a pathogen attack, which usually involves dramatic changes of gene expression across multiple signaling and metabolism pathways [1,2]
We aim to uncover the characteristics of GmTGA gene family in the Soybean mosaic virus (SMV)-susceptible soybean cultivar NN1138-2
Against our expectations, most GmTGA genes from a hypersusceptible soybean inhibited SMV multiplication in inoculated leaves of N. benthamiana (Table 2). It indicated that GmTGA genes were not responsible for the susceptibility of hyper-susceptible soybean to SMV, but for the basal resistance to SMV, and they seemed to be functionally redundant for coping with SMV stress

Summary

Introduction

Plants show a resistance or susceptibility response in facing a pathogen attack, which usually involves dramatic changes of gene expression across multiple signaling and metabolism pathways [1,2]. During plant growth and development, in defense responses and disease development, TFs often serve as transcriptional regulators in the nucleus and play a key role in manipulating gene expression by binding to specific cis-regulatory elements in the promoters of target genes [4]. TGA TF belong to Group D of the basic leucine zipper gene family, which is the largest. TF family in plants [5] This type of TF was first identified by their ability in binding to the activating sequence 1 element of the Cauliflower mosaic virus 35S promoter [6]. The sequence analysis of two TGA cDNA clones isolated from tobacco showed both proteins containing a basic leucine zipper (bZIP) domain composed of both basic and zipper regions [6].

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