Expression of the inactive ZmMEK1 induces salicylic acid accumulation and salicylic acid‐dependent leaf senescence

• DOI: 10.1111/jipb.12465
• Publication Date: 2016-01-29T09:29:10Z
• Authors: Yuan Li; Ying Chang; Chongchong Zhao; Hailian Yang; Dongtao Ren
• Keywords: 2. Zero hunger; 0301 basic medicine; Arabidopsis Proteins; MAP Kinase Signaling System; Arabidopsis; Gene Expression; Darkness; Plants, Genetically Modified; Zea mays; Plant Leaves; 03 medical and health sciences; Gene Expression Regulation, Plant; RNA, Messenger; Mitogen-Activated Protein Kinases; Phosphorylation; Salicylic Acid; Plant Proteins

AbstractLeaf senescence is the final leaf developmental process that is regulated by both intracellular factors and environmental conditions. The mitogen‐activated protein kinase (MAPK) signaling cascades have been shown to play important roles in regulating leaf senescence; however, the component(s) downstream of the MAPK cascades in regulating leaf senescence are not fully understood. Here we showed that the transcriptions of ZmMEK1, ZmSIMK1, and ZmMPK3 were induced during dark‐induced maize leaf senescence. Furthermore, in‐gel kinase analysis revealed the 42 kDa MAPK was activated. ZmMEK1 interacted with ZmSIMK1 in yeast and maize mesophyll protoplasts and ZmSIMK1 was activated by ZmMEK1 in vitro. Expression of a dominant negative mutant of ZmMEK1 in Arabidopsis transgenic plants induced salicylic acid (SA) accumulation and SA‐dependent leaf senescence. ZmMEK1 interacted with Arabidopsis MPK4 in yeast and activated MPK4 in vitro. SA treatment accelerated dark‐induced maize leaf senescence. Moreover, blockage of MAPK signaling increased endogenous SA accumulation in maize leaves. These findings suggest that ZmMEK1‐ZmSIMK1 cascade and its modulating SA levels play important roles in regulating leaf senescence.