Effects of Low-Molecular-Weight Organic Acids on Gadolinium Accumulation and Transportation in Tomato Plants

Effects of low-molecular-weight organic acids on the accumulation and transportation of gadolinium (Gd) in tomato plants were studied under hydroponic condition. The results indicated that changes of organic acids occurred in the processes of Gd accumulation and transportation in tomato plants which were treated with extraneous Gd solutions. Malic, citric, and succinic acids contributed to both Gd accumulation in roots and transportation in xylem vessels. When Gd was unloaded from the xylem to the leaf cells, formic, lactic, citric, and succinic acids played important roles in Gd accumulation in leaves. When tomato plants were cultured in the uptake solution of Gd-containing malic, citric, or succinic acid for 48 h, the succinic acid in roots and leaves and the malic acid in xylem saps both increased obviously. From the results above, we can conclude that succinic acid had the most important role in Gd accumulation in tomato roots and leaves, while malic acid transported Gd via xylem vessels more effectively.