水稻品种间吸收和转运硒特性差异机制研究

MECHANISMS OF DIFFERENCES IN SELENIUM ABSORPTION AND TRANSPORT BETWEEN RICE PLANTS DIFFERENT IN CULTIVAR

采用溶液培养试验比较了富硒水稻与非富硒水稻对硒的吸收和运输特征,期望揭示富硒水稻秀水48和非富硒水稻丙9652籽粒硒累积差异部分生理机制。结果表明,两品种水稻根部对硒吸收的Km值差异不大,但富硒水稻秀水48的Vmax是非富硒水稻的1.57倍,两品种水稻根系对硒的共质体吸收皆受载体调控。硒吸收时间动力学试验证实秀水48茎中硒的浓度和含量在各个处理时间段均要高于丙9652,富硒水稻秀水48的木质部汁液中硒的浓度大约是非富硒水稻丙9652的2倍,在相等蒸腾速率的条件下,秀水48地上部硒含量显著高于丙9652,说明两品种水稻向地上部转运硒的能力差异显著,秀水48更易将根中的硒转运到地上部,高效的转运体系是富硒品种地上部硒含量高的关键所在。富硒水稻具备很强的向地上部转运硒的能力,部分原因在于其根部木质部对硒的装载能力较强。

A hydroponic experiment was carried out to compare Se-enriching rice ＇ Xiushui 48 ＇ with Se ordinary rice ＇ Bing 9652 ＇ in Se absorption and Se transport,in expectation of revealing physiological mechanisms of the difference be- tween the two rice cultivars in selenium accumulation in grains. Results show that the two cultivars did not differ much in K,,, of Se absorption by roots,but Xiushui 48 was 1.57 times as high as Bing 9652 in V,na. The absorption of Se symplast by roots of the two rice plants was dependent on carrier. Selenium absorption time dynamics tests demonstrate that selenium concentration and content in stems of Xiushui 48 was higher than that of Bing 9652 in all the treatments and all the time,and selenium concentration in the xylem sap of Xiushui 48 was about twice as high as that of Bing 9652. The same in tran- spiration rate, Xiushui 48 was significantly higher than Bing 9652 in Se content in shoot,which indicates that the two cuhi- vars varies sharply in capacity of transport Se to shoots,that Xiushui 48 can transport Se from roots to shoots more easily, and that efficient transport system is the key to high Se content in shoots of Se enriching rice. Se enriching rice is highly capable of transporting selenium to shoots,partly because of the strong Se carrying capacity of its root xylem.