Insights Into the Gene Regulation in Jasmonate-Induced Whole-Plant Senescence of Tobacco Under Non-Starvation Condition.

Jasmonate (JA)-induced plant senescence was mainly studied with the dark/starvation-promoted system using detached leaves, yet the induction of whole-plant senescence by JA remains largely unclear. This work reports the finding of a JA-induced whole-plant senescence of tobacco under light/non-starvation condition and the investigation of underlying regulations. MeJA (methyl jasmonate) treatment induces the whole-plant senescence of tobacco in a light-intensity-dependent manner, which is suppressed by silencing of NtCOI1 that encodes the receptor protein of JA-Ile (the bioactive derivative of JA). MeJA treatment could induce the senescence-specific cysteine protease gene SAG12 and another cysteine protease gene SAG-L1 to high expression levels in the detached leaf patches under dark condition, but failed to induce their expression in tobacco whole-plants under light condition. Furthermore, MeJA attenuates RuBisCo activase (RCA) level in the detached leaves, but has no effect on this protein in the whole-plant under light condition. Genome-wide transcriptional assay also supports the presence of a differential regulatory pattern of senescence-associated-genes (SAGs) in the MeJA-induced whole-plant senescence under non-starvation condition and results in the finding of a chlorophylase activity increase in this process. We also observed that the MeJA-induced senescence of tobacco whole-plant is reversible, which is accompanied with a structural change of chloroplasts. This work provides novel insights into the JA-induced plant senescence under non-starvation condition and is helpful to dissect the JA-synchronized process of whole-plant senescence.