Expression profiles of Populus NAC genes in wood-forming tissues. Microarray data were obtained from PopGenIE ftp://aspnas.fysbot.umu.se/. The expression data were gene-wise normalized and hierarchical clustered with average linkage. Each row corresponds to the relative expression levels normalized against the maximum value. Color scale at the top of each dendrogram represents relative expression levels: green represents low level and red indicates high level. A. Dynamic expression levels of 11 NAC genes in different states of cambiums. YR1 to YR9 represent the nine sampling time points from 20 April (before bud break) until 13 December (cambium dormant). B. Expression patterns of 19 NACs in active and dormant cambiums. C, D. Hierarchical clustering of expression profiles of 19 NAC genes in the cambial region. Phl, phloem; A, meristematic cells; B, early expansion; C, late expansion; D, secondary wall formation; E, late cell maturation. CS2A1, CS2A2, CS2B1, CS2B2 and CS2B4, phloem; CS2A3, CS2A4, CS2B6 and CS2B7, cambium region; CS2A5, CS2A7, CS2A8 and CS2B8, xylem. E. Expression pattern of three NAC genes in cambium regions. The tissues are the same as depicted in C and D. F. Expression profiles of 14 NACs in vascular tissues. Phl, phloem; C, cambium; EX, expanding xylem; MX0, initiation of secondary cell-wall deposition stage; MX1-3, maturing xylem. G. Deferential expressions of 21 NAC genes during the xylem differentiation. EX, early xylem; LX, late xylem.