RETRACTED: Alternative oxidase is involved in leaf senescence via regulation of Salicylic acid accumulation in tomato

Abstract

Leaf senescence is a highly complex and coordinated process that involves ordered and continuous changes in the external environment and endogenous signaling pathways. Alternative oxidase (AOX), a key enzyme in the respiratory pathway, is involved in the regulation of plant senescence. Salicylic acid (SA) and reactive oxygen species (ROS), two significant inducers of plant senescence, also play an important role in plant senescence, but the relationship between AOX, ROS and SA is unclear. In this study, an RNA interference and overexpression transgenic strain of AOX was constructed using tomato as experimental material. It was found that AOX was able to reduce the accumulation of ROS during dark-induced plant senescence, and that AOX suppressed the synthetic gene SALICYLIC ACID INDUCTION DEFICIENT 2 (SID2) in the SA signaling pathway and salicylate receptor gene NONEXPRESSER OF PR GENES 1 (NPR1), decreasing endogenous SA content and blunting SA perception in plant leaf cells, thereby inhibiting SA-induced leaf senescence. Also, spraying the plants with ROS and ROS scavengers revealed that the synthesis of endogenous SA was affected and that AOX eliminated excess ROS, which in turn affected the SA content and delayed plant senescence. Based on these results, we propose that AOX mediates SA synthesis by balancing ROS content and plays a key role in leaf senescence.