Effects Of Nonselective Cation Channels On The Characteristics Of Cd Uptake And Transport In Rice

The absorption and accumulation of rice to the cadmium (Cd) need many steps and ways.Nonselective cation channels (NSCCs) are among the important channels for Cd uptake in rice. Seedlings and seeds from the high and low cadmium accumulation varieties of rice were used to study the influence of the NSCCs and the proton pump genes on Cd absorption and accumulation. The main results were as follows:1、Two kinds of mechanisms, i.e. the low-affinity transport system and the high-affinity transport system, were responsible for the Cd uptake in rice root and shoot. Efficiencies of Cd absorption and transport in seedlings from the high-Cd-accumulation variety were apparently higher than that from low-Cd-accumulation variety. Genetic difference among varieties affected Cd accumulation of rice root and shoot.2、NSCCs played an important role in the process of Cd absorption and transport. The contribution of NSCCs to Cd accumulation in shoot was higher than that in root of rice seedling. The contribution rate of NSCCs to Cd accumulated in the shoot of the low-Cd-accumulation variety was93.5%under the Cd concentration of0.1mg·L-1, which was greater than that of the high-Cd-accumulation variety. It was found that the higher Cd concentration in the environment, the lower NSCCs contribution rate to Cd accumulation. NSCCs might be a significant part of the high-affinity transport system in rice and could transport Cd with low concentration to the shoot effectively. LaCh could inhibit the Cd absorption through the NSCCs under the LaCl3concentration of2.69×10-4mg·L-1.3、Under the Cd concentration of0.3～1.0mg·L-1, Cd absorption of grain in vitro had significant genetic difference. Cd accumulations in high-Cd-accumulation varieties were greater than that in the low-Cd-accumulation varieties. NSCCs inhibitor LaCl3had significant influence to Cd absorption and transport through grain base and the sensitivity to the inhibitor was different among varieties. The Cd absorption of grains from different rice varieties in vitro under the Cd concentrate of 0.3mg·L-1was closely related to the Cd content of grains from10varieties planted in field with Cd concentration of1.68mg·L-1.4、The proton pump genes were not the only factors to decide Cd absorption and accumulation. The tested genes in this paper were not closely related with Cd accumulation in rice grains.