Phloem Proteomics to Identify Small Open Reading Frame ( sORF )‐encoded Peptides With a Putative Role in the Control of Flowering Time in Arabidopsis

Phloem sap proteomic studies have previously revealed that phloem sap composition varies during development and upon floral induction. Specific proteins, lipids, messenger RNAs (mRNAs), and peptides have been shown to accumulate at different developmental stages. Peptides are of special interest since they have the potential to act as regulatory molecules controlling plant responses to environmental changes, such as salinity and water stress, plant-microbe interactions, and developmental changes. In this context, we have characterized Arabidopsis thaliana phloem exudates to identify proteins and peptides with the potential to control flowering time, acting as signals fine-tuning plant development. In this work, we present the proteomic profiles of the phloem sap samples during floral transition along with the identification of proteins and peptides that showed changes in abundance during floral transition, suggesting that they could potentially have a role in the control of flowering. Among those, we have described the abundance pattern of the sORF1511 peptide in the phloem sap, which varies upon floral induction. We show that sORF1511 overexpression affects bolting time and alters the expression of several genes involved in the control of flowering time.