High-fidelity fluorescent probes for visualizing the inhibitory behavior of selenium on cadmium uptake in rice

Cadmium (Cd), a widespread and highly toxic environmental contaminant, has seriously impacted the growth of rice and the quality of its products. Hence, it is crucial to monitor and employ robust means to reduce Cd levels in rice, and selenium (Se) has been proven to chelate cadmium ion (Cd2+) in rice with rational use. Herein, for the first time, the reported selenocysteine (Sec) probe NN-Sec and the newly designed Cd2+ probe SCP were chosen as visualization tools to monitor Sec-inhibited Cd2+ uptake in rice. Specifically, reduced fluorescence of rice precultured with Cd2+ was observed by SCP after Se application, while similarly decreased fluorescence of rice pretreated with Se was observed by NN-Sec after Cd2+ addition. The diminished fluorescence indicated the formation of Cd-Se complexes reduced the Cd2+ content in rice. Additionally, it was Cd2+ and Se that entered the rice causing the fluorescence generation, as demonstrated by inductively coupled plasma mass spectrometry (ICP-MS). To conclude, the two probes successfully visualized Se inhibited Cd2+ uptake in rice, which could provide a robust tool for supporting the development of novel organic fertilizers and reagents to reduce Cd2+ content in rice and the environment.