关键词: 铊, 草酸, 阴离子通道抑制剂, 吸收和分配, 水稻（Oryza sativa L.）

Abstract: As a non-essential, highly toxic heavy metal element, thallium (Tl) interferes with normal development of plants and causes serious toxicity accumulation in food chain. Root secretion of organic acids plays an important role in the resistance against heavy metal pollution. In order to study the relationship between heavy metal absorption and organic acid tolerance mechanisms under Tl stress, the oxalate secretion and Tl distribution under T1 stress were studied by hydroponic method. Oxalate content and Tl absorption and distribution in rice (Oryza sativa L.) were analyzed. With the increase of Tl concentration from 10 to 25 μmol·L^-1, the content of oxalate secreted in rice rhizosphere was increased gradually; however, the amount of oxalate secretion was gradually decreased with the prolongation of Tl stress time. Anion channel inhibitors phenylglyoxal (PG) and niflumic acid (NIF) significantly inhibited the excretion of oxalate in roots, and the inhibition of NIF was stronger than that of PG. The roots of rice could accumulate more Tl than leaves, and root cytoplasm was the main location of Tl storage. There was a significant positive correlation between oxalate content in root and Tl content in plant (r=0.923, P<0.01). It was suggested that oxalate in rice roots played an important role in the tolerance to Tl in rice plants.

Key words: thallium(Tl), oxalate, anion channel inhibitor, uptake and distribution, rice (Oryza sativa L.)