PROTECTIVE EFFECTS OF MELATONIN LIPOSOME NANOPARTICLES ON MEDICAGO SATIVA L. SEEDLINGS UNDER CADMIUM STRESS

Cadmium (Cd) is one of the main heavy metals causing global environmental pollution, and it is also the heavy metal with the strongest toxic effect on growth and development of crops and other plants. In this study, we established six treatment groups, including normal culture group (CK), exogenous melatonin treatment group (MT), treatment with cadmium chloride stress and exogenous melatonin group (Cd+MT), compound treatment with cadmium chloride stress and melatonin liposome nanoparticles group (Cd+MT-SLNs). We found that CdCl2 stress inhibited the growth of alfalfa seedlings and decreased cell viability, resulting in significant cadmium stress damages by measuring and analyzing plant phenotype, cell viability, stress damage, reactive oxygen species scavenging system, and Cd accumulation of alfalfa seedlings under six conditions. At the same time of cadmium stress, spraying MT or MT-SLNs significantly increased the cell viability of alfalfa seedling leaves, and significantly induced antioxidant synthesis and antioxidant enzyme activity. The levels of ROS (Reactive oxygen species) and free Cd accumulation in tissues decreased, indicating that exogenous MT or MT-SLNs can effectively alleviate the inhibitory effect of CdCl2 stress on alfalfa by activating the reactive oxygen species scavenging system and promoting Cd efflux, and spraying MT-SLNs has a more significant protective effects on alfalfa seedling cadmium stress. In addition, spraying MT or MT-SLNs under normal growth conditions is also beneficial for the growth and development of plant seedlings.