Transcription factors responsive to P-stress
Consistent with the massive transcriptional reprogramming evident from transcriptome analysis, several families of transcription factor (TF) genes were found to be enriched amongst DEGs, (Figure 5c ). These included the TF families AP2, bHLH, bZIP, MYB, WRKY, NAC, and GRAS (Figure S4) . Under severe P-stress, more than twice as many TF genes were repressed than were induced, consistent with the overall greater number of genes repressed than induced under these growth-limiting conditions (Figure 5b ). Further analysis of TF families showed that 75% of the GRAS TF family were induced in roots while 95% of the B3 TFs family were induced in roots and shoots (Figure S4 ).