Silencing Autophagy-Related Gene 2 (ATG2) Results in Accelerated Senescence and Enhanced Immunity in Soybean.

Said Hashimi,Ni-Ni Wu,Jie Ran,Jian-Zhong Liu

doi:10.3390/ijms222111749

Said Hashimi, Ni-Ni Wu + Show 2 more

Open Access

https://doi.org/10.3390/ijms222111749

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Abstract

Autophagy plays a critical role in nutrient recycling and stress adaptations. However, the role of autophagy has not been extensively investigated in crop plants. In this study, soybean autophagy-related gene 2 (GmATG2) was silenced, using virus-induced silencing (VIGS) mediated by Bean pod mottle virus (BPMV). An accelerated senescence phenotype was exclusively observed for the GmATG2-silenced plants under dark conditions. In addition, significantly increased accumulation of both ROS and SA as well as a significantly induced expression of the pathogenesis-related gene 1 (PR1) were also observed on the leaves of the GmATG2-silenced plants, indicating an activated immune response. Consistent with this, GmATG2-silenced plants exhibited a significantly enhanced resistance to Pseudomonas syringae pv. glycinea (Psg) relative to empty vector control plants (BPMV-0). Notably, the activated immunity of the GmATG2-silenced plants was independent of the MAPK signaling pathway. The fact that the accumulation levels of ATG8 protein and poly-ubiquitinated proteins were significantly increased in the dark-treated GmATG2-silenced plants relative to the BPMV-0 plants indicated that the autophagic degradation is compromised in the GmATG2-silenced plants. Together, our results indicated that silencing GmATG2 compromises the autophagy pathway, and the autophagy pathway is conserved in different plant species.

Highlights

Autophagy is a fundamental recycling intracellular constituent pathway among eukaryotes, including yeast, C. elegans, Drosophila melanogaster, humans and plants [1,2]
We found that GmATG2 has two copies in the soybean genome (Glyma.02G133400 and Glyma.07G211600, referred to as GmATG2a and GmATG2b, respectively), sharing an identity above 96% at the nucleotide level
The similar phenotypes were not seen for the GmATG2-silenced plants under natural growth conditions (Figure 1A,B)

Summary

Introduction

Autophagy is a fundamental recycling intracellular constituent pathway among eukaryotes, including yeast, C. elegans, Drosophila melanogaster, humans and plants [1,2]. This process is essential for plants’ adaptation to a variety of environmental stresses, including nutrient deprivation, oxidative stress, salt, drought, and pathogen attack [1,2]. Around 40 ATG genes have been characterized in yeast, and most of them have homologs in plants [1,2], suggesting the conservation of the core ATG process during evolution. Selective autophagy plays a crucial role in the clearance of invading pathogens, such as bacteria, viruses, and fungi [20,21,22,23,24,25]

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