Transcriptome response to embolism in stems of P. trichocarpa

Embolism and the refilling of xylem vessels are intrinsic to the ability of plants to handle the transport of water under tension. While the formation of an embolized vessel is an abiotic process, refilling against the pressure gradient requires biological activity to provide both the energy and the water needed to restore xylem transport capacity. We used microarrays to analyze the global transcriptome response of xylem parenchyma cells after embolism formation or infiltration of xylem tissue with sucrose solution. Plants subjected to artificial embolism treatment (ET), to sucrose infiltration treatment (ST), and controls (C) were selected for RNA extraction and hybridization on Affymetrix microarrays. Embolism was artificially induced through air-injection into the stems of the ET plants, while ST plants were exposed to osmotic stress by adding sucrose to the growing solution. Woody stems were respectively collected 90 minutes following the injection and after 90 minutes of exposure to sucrose.