“…We were interested in developing a biosensor for MAPK activity in Arabidopsis because of the central role that these kinases play in a wide range of signaling pathways. Our current understanding of MAPK function in Arabidopsis is based on extensive genetic and biochemical studies which have demonstrated roles for MAPK signaling in both stress responses and developmental regulation (Rodriguez et al ., ; Moustafa et al ., ; Xu and Zhang, ; Liu and He, ; Devendrakumar et al ., ; Komis et al ., ; Zhang et al ., ). Of the 20 MAPK genes present in the Arabidopsis genome, mutant phenotypes have been associated with mpk1 , mpk3 , mpk4 , mpk6 , mpk8 , mpk9 , mpk10 , mpk12 , mpk17 and mpk18 (Petersen et al ., ; Bush and Krysan, ; Wang et al ., , ; Hord et al ., ; Ren et al ., ; Jammes et al ., ; Walia et al ., ; Galletti et al ., ; Takahashi et al ., ; Zeng et al ., ; Stanko et al ., ; Enders et al ., ; Zhang et al ., ; Frick and Strader, ).…”