The Mechanisms Of Fe And P On Decreasing Cadmium Accumulation In Plants

Cadmium(Cd)contamination of soil is one of the most serious problems in crop yield and nutrition quality.Therefore,the search for a technology and method that could effectively prevent Cd from entering the food chain through the plant is imminent.As we know,it is a green,economical and environmentally friendly strategy to lesser Cd uptake by Nutrient Regulation and Agronomic Management Previous studies have indicated that the application of iron(Fe)or the presence of phosphate(P)can affect Fe availability and expression of Fe-responsive genes.In addition,numerous researches have been reported that the IRT1 is also primarily responsible for taking up Cd.In the present study,Arabidopsis thaliana(Columbia ecotype,Col-0)and the mutants,irtl-1 and irtl-2 were employed to investigate the effect and mechanism of increased Fe supply and P deficiency in alleviating Cd uptake and accumulation in Arabidopsis thaliana.The main results are followed below:(1)The plants were grown in nutrient solution,we studied the effects of Cd exposure on Col-0 plants in hydrophonic system.The results showed that Cd exposure resulted in leaf chlorosis and growth inhibition in Arabidopsis.However,increased Fe supply or the absence of P prevented Cd uptake and alleviated the symptom of Cd stress in plants.Therefore,our results indicate that both increased Fe supply and P deficiency decreased Cd accumulation,thus alleviating Cd toxicity.(2)The effects of increased Fe supply and P deficiency on reactive oxygen species(ROS)generation and plasma membrane integrity in Col-0 under Cd stress were investigated by plant tissues staining.The results showed that Cd induced a significant accumulation of ROS and a serious oxidative damage.Increased Fe supply and P deficiency significantly decreased the ROS levels and alleviated oxidative damage,thus enhancing antioxidant defense to adapt to Cd stress.(3)The effect of increased Fe supply and P deficiency on the expression of IRT1 under Cd stress was investigated by using qPCR technique.The results showed that the transcriptional level of IRT1 was significantly down-regulate by increased iron supply.However,the IRT1 transcript is increased under P-deficiency.Therefore,increased Fe supply can prevent Cd uptake by ihibiting IRT1 expression.P-deficiency decreasing Cd uptake may be via non-IRT1 mediated the uptake of Cd.(4)Two Fe-Cd rotation and P-Cd rotation schemes were designed to test the effect of increased Fe supply and P deficiency on Cd uptake.The results showed that the level of Cd uptake and accumulated by plants was clearly decreased.We concluded that Fe supply by favoring the competition between the uptake of Fe and Cd is another factor in the mechsanism allowing Fe to decrease Cd levels in plants;the rotation treatment confirmed that P-deficiency decreased Cd accumulation via non IRT1-mediated uptake of Cd which is not associated with the antagonism between P and Cd.