Local and Systemic Metabolic Responses during Light-Induced Rapid Systemic Signaling.

Plants evolved multiple signaling pathways that transduce light-related signals between leaves. These are thought to improve light stress acclimation in a process termed systemic acquired acclimation. Although responses to light stress have been studied extensively in local leaves, and to a lesser degree in systemic leaves, little is known about the responses that occur in the different tissues that connect the local to the systemic leaves. These could be important in defining the specificity of the systemic response as well as in supporting the generation of different systemic signals. Here, we report that local application of light stress to one rosette leaf of bolting Arabidopsis (Arabidopsis thaliana) plants resulted in a metabolic response that encompassed local, systemic and transport tissues (stem tissues that connect the local to the systemic tissues), demonstrating a high degree of physical and metabolic continuity between different tissues throughout the plant. Our results further indicate that the response of many of the systemically altered metabolites is associated with the function of the reactive oxygen species wave and that the levels of eight different metabolites are altered in a similar manner in all tissues tested (local, systemic, and transport). These compounds could define a core metabolic signature for light stress that propagates from the local to the systemic leaves. Our findings suggest that metabolic changes occurring in cells that connect the local and systemic tissues play an important role in systemic acquired acclimation and could convey specificity to the rapid systemic response of plants to light stress.