Figure 3.

Interactions between hormones and ROS during leaf senescence regulation. Plant hormones can affect leaf aging either directly or via signaling cascades in which ROS are involved. Among them, GAs, auxins and CKs delay senescence, whereas ethylene and JA favor it. Regulation of JA accumulation via miR319 and lipoxygenase 2 (LOX2) is indicated. ROS might also act as independent signaling molecules that are produced upon leaf aging and stress conditions. ROS trigger modifications of gene expression that in turn result in reprogramming primary and secondary metabolisms involving sugars, energy, amino acids and antioxidants. Examples of reported interactions between hormones and ROS are given in the text. Abbreviations for hormones are also found there. AHK, Arabidopsis histidine kinase; AP2, Apetala 2; CKs, cytokinins; EIN, ethylene-insensitive protein; ERF, ethylene-responsive factor; ETR1, ethylene receptor 1; GNC, carbon-metabolism involved; GNL, GNC-like.