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

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.