As one of the major hormones in plant, ethylene plays an important role in regulating numerous physiological events, including flowering. Although being extensively studied, the detailed mechanism of how ethylene regulates flowering is not well-understood. In another aspect, emerging evidences have suggested the existence of alternative signaling pathway of ethylene in Arabidopsis.

To explore the novel components in ethylene signaling pathway, a phosphoproteomics analysis was carried out to investigate the differential phosphorylation profile in response to 12-hour ethylene treatment in ethylene-insensitive mutant ein2-5. A total of 224 phosphopeptides were identified, of which 6 phosphopeptides were repetitively associated with ethylene treatment. Five conserved phosphorylati...[ Read more ]

As one of the major hormones in plant, ethylene plays an important role in regulating numerous physiological events, including flowering. Although being extensively studied, the detailed mechanism of how ethylene regulates flowering is not well-understood. In another aspect, emerging evidences have suggested the existence of alternative signaling pathway of ethylene in Arabidopsis.

To explore the novel components in ethylene signaling pathway, a phosphoproteomics analysis was carried out to investigate the differential phosphorylation profile in response to 12-hour ethylene treatment in ethylene-insensitive mutant ein2-5. A total of 224 phosphopeptides were identified, of which 6 phosphopeptides were repetitively associated with ethylene treatment. Five conserved phosphorylation motifs were found via bioinformatic analysis, and ERF110, a transcriptional factor predicted to be involved in ethylene signaling, was predicted to bear one conserved phosphorylation motif PRVDS̲S.

The predicted phosphorylation site of ERF110 was validated in vivo and found to be involved in regulating flowering time. To better understand the regulatory mechanism of ethylene on ERF110, we analyzed the protein abundance as well as phosphorylation level of ERF110 in vivo in several key ethylene mutants in Arabidopsis. An agar-based growth system was established to observe flowering time in ethylene mutants and RNAi lines of ERF110. By physiological studies combining with functional phosphoproteomics approaches, an association was established between the ethylene-dependent phosphorylation event at Ser62 of ERF110 and the bolting time of Arabidopsis. A potential downstream flowering gene AP1 was also found to be regulated transcriptionally by ERF110. Coupling all these results, it was suggested that ethylene regulates bolting time in both stimulative and repressive way or in a dual-and-opposing fashion, via enhancing ERF110 gene expression at transcriptional level and repressing phosphorylated isoform at post-translational level in EIN2-dependent and independent manner, respectively.