Abstract: 【Objective】Rice seedlings enriched with zinc (Zn) is a new method to antagonize cadmium (Cd) within rice, studying the various effects and underlying mechanisms among different rice cultivars is useful to provide a basis for the application of this method. 【Method】Hydroponic and pot experiments were conducted to test the effects of the Zn enrichment in four cultivars including the Wuyunjing21, Zhejingyou1578, Huanghuazhan, and Huiliangyousimiao. Dynamics of Zn accumulation in different cultivars, and variations of Cd uptake and transport in rice tissues were investigated. Furthermore, the expressions of the Cd-related transporter genes of the root were analyzed to explore the underlying mechanisms responsible for the various effects in different cultivars. 【Result】Results showed that the Zn cultivation didn’t affect the growth of all rice seedlings. Zn accumulations varied obviously among different cultivars, the Zhejingyou1578 had the highest Zn level (230 μg Zn per plant), followed by the Wuyunjing21 (124 μg Zn per plant), the Huanghuazhan and Huiliangyousimiao had the low levels (85.1-95.0 μg Zn per plant). Zn enrichment greatly influenced the expression of Cd-related transporters in the Zhejingyou1578, the OsZIP7 was down-regulated by 48.7% and OsZIP1 was up-regulated by 81.3%. The expressions of the OsIRT1 and OsZIP7 in the Wuyunjing21 were also down-regulated by 35.9% and 35.0%, respectively, and the OsZIP1 was up-regulated by 31.1%. However, the Cd-related transporters in the Huanghuazhan and Huiliangyousimiao were insensitive to Zn enrichment. As a result, Zn enrichment significantly reduced Cd concentrations in the root and shoot by 26.7% and 36.7% of the Wuyunjing21, and 32.0% and 40.0% of the Zhejingyou1578 with an 12.0% inhibition on the Cd transport, respectively. Furthermore, brown rice Cd were reduced by 37.5%, 36.7% and 25.3% in the Wuyunjing21, Zhejingyou1578, and Huanghuazhan, respectively, while no difference occurred in the Huiliangyousimiao, revealing various effects on reducing Cd among different cultivars induced by the Zn enrichment. Correlation analysis showed that the brown rice Cd was negatively correlated with the shoot Cd which was negatively correlated with the root and shoot Zn, revealing a significant antagonism between Zn and Cd within rice. However, the root and shoot Zn were negatively correlated with the OsZIP7 and OsIRT1 and positively correlated with the OsZIP1 expression, indicating that the Zn enrichment within seedlings influenced the brown rice Cd mainly through regulating the expressions of the OsZIP1, OsZIP7 and OsIRT1. 【Conclusion】The regulations on Cd-related transporters through Zn enrichment were varied among different cultivars, and the Zhejingyou1578 and Wuyunjing21 were more sensitive, so that the reductions of brown rice Cd were higher than other cultivars.

Key words: soil Cd contamination, antagonistic effect, transporter gene, brown rice, correlation analysis