| Solution culture experiments were carried out to study the uptake and translocation of selenate (Na2SeO4) or selenite (Na2SeO3) by wheat and rice seedlings. When supplied with Na2SeO4 in nutrient solution, the concentrations of selenium (Se) in normal shoots and roots of rice were 30.3 mg·kg-1and 39.0 mg·kg-1 respectively, and the absorbed Se was quickly translocated to shoots accounting for 80% of the total uptake. Se concentrations in wheat shoots and roots were 1.76 mg·kg-1 and 6.99 mg·kg-1 respectively, accounting for 62% in shoots. However, when supplied with Na2SeO3, Se concentrations in shoots and roots of rice were 4.40 mg·kg-1 and 230 mg·kg-1 respectively, 1.24 mg·kg-1 and 88.3 mg·kg-1in shoots and roots of wheat respectively, and only 8.2% was transferred to shoots. The influence of phosphorus (P) starvation on Se uptake was different for rice and wheat seedlings. Comparing to normal plants, the Se concentrations in the shoots and roots of rice under P starvation condition were decreased, however increased for wheat. In Na2SeO3 uptake kinetics, Km of wheat seedlings was 8.7 folds of that of rice, and the affinity of wheat root to selenite was much weaker than that of rice. The Se uptake rate of wheat (Vmax) was 14% lower than that of rice. The uptake and translocation mechanisms of selenate and selenite by rice and wheat seedlings were revealed. And the results demonstrate that the absorbed selenate is quickly translocated to shoot and selenite is mainly accumulated in root. These results provide basic information for biofortification of crops with Se. |
