## 2 Materials and Methods
### Sample Preparation for Proteomics Analysis  
Leaf material was pulverized with the aid of a mortar and pestle in the presence of liquid nitrogen. For each individual sample, 100 mg of ground powder was further homogenized in 250 \(\upmu\)L lysis buffer (7M Urea, 2M Thiourea, 4% CHAPS, 1% DTE, and 2% IPG ampholytes) in a 2 mL safelock polypropylene tube with one stainless steel bead (3 mm diameter) using the Tissue Lyser LT (Qiagen, Tegelen, The Netherlands). Two rounds of homogenization were performed at 50 Hz for 6 min each. Samples were then centrifuged at 14,000 ref for 10 min at room temperature, and 100 \(\upmu\)L of the supernatant of each sample was transferred in a clean tube. Protein concentration was determined by Bradford assay and the extract volume containing 200 \(\upmu\)g of total protein was calculated for each sample and transferred to a new tube. To this, protease inhibitors (Roche, Basel, Switzerland) were added at a final concentration of 3.6% \(v/v\) of extract volume, making the sample ready for immediate use. The rest of the protein extracts were stored at \(-80\)\({}^{\circ}\)C until further use. An aliquot of 10 \(\upmu\)g (approximately 3-7 \(\upmu\)L) of each protein extract resuspended in 4\(\times\) Laemmli buffer and H\({}_{2}\)O up to a final volume of 20 \(\upmu\)L, was run in a FastGene Polyacrylamide Gel Electrophoresis precast 4% stacking-12% separating gradient gel (NIPPONGenetics, Duren, Germany), with MOPS Buffer, at 100 Volts constant until the dye reached the bottom of the gel. The gels were fixed with 30% MetOH-10% acetic acid for 30\({}^{\prime}\), washed 3 \(\times\) 10\({}^{\prime}\) with dH\({}_{2}\)O, stained overnight with Coomassieic colloidal blue, and de-stained with 3 \(\times\) 10\({}^{\prime}\) washes of dH\({}_{2}\)O before scanning the gels at a GS-800 imaging densitometer (BioRad, Hercules, CA, USA) in transmission mode (Supplementary Figure S1). Protein extracts (200 ug per sample) were processed using filter-aided sample preparation (FASP) as described previously [58], with some minor modifications [59]. Briefly, buffer exchange was performed in 0.5 mL, 30 kDa MWCO, Amicon Ultra Centrifugal filter devices (Merck Millipore), mixing each sample volume with 200 \(\upmu\)L urea buffer (8M Urea in 0.1M Tris-HCl pH 8.5) and subsequent centrifugation at 14,000 rcf for 15 min at room temperature (RT). An additional 200 \(\upmu\)L urea buffer volume was added to the filter subsequently centrifuged at 14,000 rcf for 15 min at RT. This procedure was repeated twice. Alkylation of proteins was performed with 0.05 M iodoacetamide in urea buffer for 20 min in the dark, at RT, followed by a centrifugation at 14,000 rcf for 15 min at RT. Additional series of washes were conducted with urea buffer twice, and ammonium bicarbonate (ABC) buffer (50 mM NH\({}_{4}\)HCO\({}_{3}\) pH 8.5) twice. Tryptic digestion was performed in ABC buffer using a trypsin-to-protein ratio of 1:100 \(w/w\). Trypsinization was performed overnight at RT in the dark. Peptides were eluted by centrifugation at 14,000 rcf for 10 min at RT, lyophilized, and stored at \(-\)80 \({}^{\circ}\)C until further use. Nano-Liquid Chromatography-High Resolution Tandem Mass Spectrometry (Nano-LC-HRMS/MS) Q-Exactive-Orbitrap Analysis  
Samples were initially resuspended in 200 \(\upmu\)L mobile phase A (0.1% Formic Acid (FA)) and 6 \(\upmu\)L from each sample was injected into a Dionex Ultimate 3000 RSLS nano flow system coupled to a Thermo Q Exactive mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). A Dionex 0.1 \(\times\) 20 mm, 5 \(\upmu\)m, 100 A C18 nano trap column with a flow rate of 5 \(\upmu\)L/min was used. The analytical column was an PepMap C18 nano column, 75 \(\upmu\)m \(\times\) 50 cm, 2 \(\upmu\)m 100 A with a flow rate of 300 nL/min. Both trap and nano-flow columns were maintained at 35 \({}^{\circ}\)C. The nano-pump mobile phase A was H\({}_{2}\)O, 0.1% FA, and B was ACN:0.1% FA.