Salicylic acid metabolism and signalling coordinate senescence initiation in aspen in nature

Deciduous trees exhibit a spectacular phenomenon of autumn senescence driven by the seasonality of their growth environment, yet there is no consensus which external or internal cues trigger it. Senescence starts at different times in European aspen (Populus tremula L.) genotypes grown in same location. By integrating omics studies, we demonstrate that aspen genotypes utilize similar transcriptional cascades and metabolic cues to initiate senescence, but at different times during autumn. The timing of autumn senescence initiation appeared to be controlled by two consecutive switches; 1) first the environmental variation induced the rewiring of the transcriptional network, stress signalling pathways and metabolic perturbations and 2) the start of senescence process was defined by the ability of the genotype to activate and sustain stress tolerance mechanisms mediated by salicylic acid. We propose that salicylic acid represses the onset of leaf senescence in stressful natural conditions, rather than promoting it as often observed in annual plants. Deciduous trees exhibit autumn senescence driven by environmental seasonality. Here, the authors show that senescence timing in aspen tree genotypes depends on environmental changes but also on the ability of each genotype to sustain stress tolerance mediated by the phytohormone salicylic acid.

Automated summary

Deciduous trees exhibit autumn senescence driven by environmental seasonality, with different genotypes starting senescence at different times. By integrating omics studies, the researchers found that aspen genotypes utilize similar transcriptional cascades and metabolic cues, but the timing of senescence initiation is controlled by environmental changes and the ability of each genotype to sustain stress tolerance mediated by salicylic acid.