Abstract: Background, aim, and scope Cadmium (Cd) is a heavy metal that causes serious damage to plants and animals, but little research has been done on how it gets into cells and how it affects plant development. In this paper, how Cd got into plant cells and how the stoma developed when Cd existed were studied. Materials and methods By investigating the growing states of Impatiens balsamina L., Pharbitis nil (L.) Choisy and Mirabilis jalapa L. in cadmium pollution environment, using Typan Blue stain root cells, and making model of leave epidermis, the possible way of cadmium got into cells was studied, and a model for cadmium got into plant cells was put forward. At the same time, the influence of cadmium on stoma development was investigated. Results When I. balsamina L. grown in culture solution containing cadmium, the root cells nuclear could be stained by Typan Blue, if not, the root cells nuclear couldn’t be stained. The number of stomas was reduced and more stomas closed than the plants grown in culture solution without cadmium. P. nil (L.) Choisy had subsidiary cells in normal development, but the subsidiary cells did not appear if there was Cd. The number of stomas decreased when there were Cd, while the stomas number of I. balsamina L. decreased most. At same time the epidermis cell wall had a difference. Discussion The existing results suggested that Cd absorption was not related with ATPase and it had little relationship with the Cd flow of high cadmium on the root surface. Cd could influence the development of secondary structures. All of the results did not contradict the results of our experiment. Conclusions Cd destroyed cell membrane, allowing Cd2+ to entry cells freely, thus the plant development and the function were inhibited. Recommendations and perspectives Based on the grow state of three species and the morphology of the plant dead, the model of cadmium entered into plant cells was put forward, that was: the cadmium first combined with protein on membrane, then formed a pore near the protein and finally diffused into plant cell. Cd2+ combined with protein could also dissociate. Cadmium affected stomatal opening and closing, when there were Cd, the more stomas closed. In the development of leaf, if there were Cd, the stomas developed through a different way.
Keywords: cadmium; membrane; stoma; subsidiary cell; Impatiens balsamina L., Pharbitis nil (L.) Choisy and Mirabilis jalapa L.