向日葵根系水通道蛋白活性与苗龄关系的研究

利用压力室结合水通道蛋白抑制剂氯化汞(HgCl2)检测了不同苗龄(15d、25d和35d)向日葵根系水通道的活性，结果显示此生长期间根系导水率保持相对恒定，但0．1mmol／L氯化汞使所有苗龄根系的水流速率和根系导水率迅速降低，而降幅随根龄的增大而增大，表明向日葵根存在调节水分进入根系的水通道蛋白，其活性随根龄的增大而提高，质外体水流随根龄的增大而减小。结论是：在根系生长过程中，细胞到细胞途径水通道蛋白活性的提高可以补偿由于质外体途径导水度降低所致根系导水率的降低，从而维持根系导水率的相对稳定。

Aquaporin activities in sunflower root system increased with increasing seedling age

An experiment using pressure chamber and mercuric chloride (HgCl2)-an inhibitor of aquaporins (water channels) was conducted to evaluate the activities of water channels in sunflower (Helianthus annuus L.) root systems of different ages (15 d、25 d and 35 d).The results showed that root hydraulic conductivity (Lpr) maintained constant over the experiment period.Addition of 0.1 mmol/L HgCl2 to root-bathing solution caused a rapid reduction in both water flux rate (Jv) and Lpr of all ages of seedling.But the degrees of reduction differed,increasing during seedling development.The reduction in both Jv and Lpr by HgCl2 indicated that not only aquaporins could be involved in the regulation of water flow across sunflower roots but that the older root system has greater water channel activities than the younger.It is concluded that water channel activity in cell-to-cell pathway increased with increasing seedling age,which reflects a compensatory mechanism for the loss of Lpr resulting from decreased apoplastic conductance in old root segments and hence,maintaining root system hydraulic conductivity relatively constant.