The Ca2+ signaling, Glu, and GABA responds to Cd stress in duckweed

•50 μM Cd shock stimulated the Ca2+ signal via modifying the instantaneous Ca2+ flux from influx of 17 pmol·cm-2·s-1 to the efflux of 240 pmol·cm-2·s-1 at 100 μm from the rhizoid, and the Ca2+ signal transferred to the vein and mesophyll cell.•Glu content was increased by Cd stress and exogenous Glu triggered the Ca2+ signal in duckweed, while Ca2+ addition caused no influence to Glu content.•GABA, which acts as an inhibitory neurotransmitter, has been decreased with 24 h Cd treatment. And the exogenous GABA induced an aggravated root abscission under CdCl2 stress. Cadmium (Cd) affects plants and animal health seriously. Ca2+ signals in plant cells are important for adaptive responses to environmental stresses. Here we showed that 50 μM Cd shock stimulated the Ca2+ signal via modifying the instantaneous Ca2+ flux from influx of 17 pmol·cm-2·s-1 to the efflux of 240 pmol·cm-2·s-1 at 100 μm from rhizoid tip. And the Ca2+ signal transferred to the vein and mesophyll cell. The Ca addition decreased the accumulation of Cd. The gene expression of glutamate receptor–like (GLR) proteins, which is activated by Glu and triggers Ca2+ flux, was increased significantly by 24 h Cd stress. Glu content was increased under Cd stress and exogenous Glu triggered the Ca2+ signal in duckweed, while Ca2+ addition caused no influence to Glu content. GABA, which is synthesized from Glu and acts as an inhibitory neurotransmitter, has been decreased with 24 h Cd treatment. GABA addition increased the abscission rate and Glu addition decreased the abscission rate during Cd stress, suggesting that the Glu/GABA ratio is important for responding to Cd. This research shows the sight of the Glu, Ca2+, GABA signaling networks during Cd stress.