1 23 Journal of Plant Growth Regulation ISSN 0721-7595 Volume 31 Number 1 J Plant Growth Regul (2012) 31:102-112 DOI 10.1007/s00344-011-9223-y Effect of Water Deficit on Expression of Stress-related Genes in the Cambial Region of Two Contrasting Poplar Clones Grazia Pallara, Alessio Giovannelli, Maria Laura Traversi, Alessandro Camussi & Milvia Luisa Racchi