Naganand Rayapuram

Abstract Mitogen-activated protein kinase (MAPK) cascades play critical roles in plant immunity by phosphorylating downstream effectors that regulate stress responses. While MAPK-mediated transcriptional regulation has been well examined, the involvement of MAPKs in post-transcriptional and post-translational regulation is still poorly understood.

Summary MAPKs are universal eukaryotic signaling factors whose functioning is assumed to depend on the recognition of a common docking motif (CD) by its activators, substrates, and inactivators. We studied the role of the CD domain of Arabidopsis MPK4 by performing interaction studies and determining the ligand-bound MPK4 crystal structure. We revealed that the CD domain of MPK4 is essential for interaction and activation by its upstream MAPKKs MKK1, MKK2, and MKK6.

Mutant collection development We mutagenized 2,700 seeds of the wheat–Th. elongatum introgression line RWG34 containing Sr43 (ref. 29). Dry seeds were incubated for 16 h with 200 ml of a 0.8% (w/v) EMS solution with constant shaking on a Roller Mixer (Model SRT1, Stuart Scientific) to ensure maximum homogenous exposure of the seeds to EMS. The excess solution was then removed and the seeds were washed three times with 400 ml of tap water.