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Fig. S1 Real time qRT-PCR validation of expression changes in genes found to be regulated by the array analysis.

Fig. S2 pta-miR164e and its target gene PtaNAC1.

Fig. S3 Root and shoot characteristics of transgenic poplars with modified expression of PtaNAC1.


Table S1 Differentially expressed genes (DEGs) in poplar roots in response to low nitrogen (LN)

Table S2 The overlapping genes among differentially expressed genes (DEGs) at different time-points

Table S3 Temporal trends in gene ontology (GO) term enrichment among the differentially expressed genes (DEGs)

Table S4 Gene ontology (GO) terms enriched in each hub gene sub-network as shown in Fig. 3

Table S5 Primers used in qRT-PCR expression analysis