The group D MPKs represent the largest group of MPKs in poplar, as they do in Arabidopsis and rice [4,39]. In rice and alfalfa (Medicago sativa), two group D MAPK genes (OsBMWK1 and MsTDY1) are induced transcriptionally by pathogen challenge and wounding, respectively [36,46] Activated OsBMWK1 (now annotated as OsMPK17-1 [39]) has also been shown to phosphorylate a transcription factor that binds a cis-acting element in the promoter of defence-related genes [47].