Isolation of Apoplastic Fluid from Woody Plant Leaves: Grapevine and Coffee as a Case Study

Proteomics is one of the key approaches to understand plant cell physiology involving the regulation of expression of many genes and metabolite production. Technical advances allowed a deeper characterization of plant proteomes, highlighting the need to study cellular compartments. The apoplast is the cellular compartment external to the plasma membrane including the cell wall, where a broad range of processes take place including intercellular signaling, metabolite transport, and plant-microbe interactions. Due to the fragile nature of leaf tissues, it is a challenge to obtain apoplastic fluids from leaves while maintaining cell integrity, which is particularly true for woody plants. Here, we describe the vacuum infiltration-centrifugation (VIC) method for the extraction of the apoplastic fluid compatible with high-throughput proteomic approaches and biochemical analysis from different woody plants.