Silencing GmATG7 Leads to Accelerated Senescence and Enhanced Disease Resistance in Soybean.

Autophagy plays a critical role in nutrient recycling/re-utilizing under nutrient deprivation conditions. However, the role of autophagy in soybeans has not been intensively investigated. In this study, the Autophay-related gene 7 ( ATG7 ) gene in soybeans (referred to as GmATG7 ) was silenced using a virus-induced gene silencing approach mediated by Bean pod mottle virus (BPMV). Our results showed that ATG8 proteins were highly accumulated in the dark-treated leaves of the GmATG7 -silenced plants relative to the vector control leaves (BPMV-0), which is indicative of an impaired autophagy pathway. Consistent with the impaired autophagy, the dark-treated GmATG7 -silenced leaves displayed an accelerated senescence phenotype, which was not seen on the dark-treated BPMV-0 leaves. In addition, the accumulation levels of both H 2 O 2 and salicylic acid (SA) were significantly induced in the GmATG7 -silenced plants compared with the BPMV-0 plants, indicating an activated immunity. Consistently, the GmATG7 -silenced plants were more resistant against both Pseudomonas syringae pv. glycinea ( Psg ) and Soybean mosaic virus (SMV) compared with the BPMV-0 plants. However, the activated immunity in the GmATG7 -silenced plant was not dependent upon the activation of MPK3/MPK6. Collectively, our results demonstrated that the function of Gm ATG7 is indispensable for autophagy in soybeans, and the activated immunity in the GmATG7 -silenced plant is a result of impaired autophagy.