Cadmium (Cd) causes serious damage to plants. Although calcium (Ca) signal has been found to respond to certain stress, the localization of Ca and molecular mechanisms underlying Ca signal in plants during Cd stress are largely unknown. In this study, Ca2+-sensing fluorescent reporter (GCaMP3) transgenic duckweed showed the Ca2+ signal response in Lemna turionifera 5511 (duckweed) during Cd stress. Subsequently, the subcellular localization of Ca2+ has been studied during Cd stress by transmission electron microscopy, showing the accumulation of Ca2+ in vacuoles. Also, Ca2+ flow during Cd stress has been measured. At the same time, the effects of exogenous glutamic acid (Glu) and γ-aminobutyric (GABA) on duckweed can better clarify the signal operation mechanism of plants to Cd stress. The molecular mechanism of Ca2+ signal responsed during Cd stress showed that Cd treatment promotes the positive response of Ca signaling channels in plant cells, and thus affects the intracellular Ca content. These novel signal studies provided an important Ca2+ signal molecular mechanism during Cd stress.
Keywords: Calcium; Cd stress; GCaMP3 duckweed; ruthenium red; subcellular localization.