Purification and Proteomics Analysis of Phloem Tissues from Virus-Infected Plants

The plant phloem vasculature is crucial for plant growth and development, and is essential for the systemic movement (SM) of plant viruses. Recent transcriptomic studies of the phloem during virus infection have shown the importance of this tissue, yet transcript levels do not provide definitive answers how virus-host interactions favour successful viral SM. Proteomic analyses have been used to identify host-virus protein interactions, uncovering a variety of ways by which viruses utilize host cellular machinery for completion of the viral infection cycle. Despite this new evidence through proteomics, very few phloem centric studies during viral infection have been performed. Here, we describe a protocol for the isolation of phloem tissues and proteins and the subsequent label-free quantitation (LFQ), for identification of proteomic alterations caused by viral infection.