玉米叶细胞磷吸收动力学性质

KINETICS OF PHOSPHATE UPTAKE BY CELLS OF MAIZE MATURE LEAF

利用32P示踪技术测定了玉米成熟叶的细胞质膜囊泡对磷酸根离子的吸收。结果表明,磷饥饿胁迫下,玉米成熟叶对磷的吸收能力(Vmax)显著增强(P<0.01);在成熟叶片上进行的32P-KH2PO4溶液施加试验显示,叶细胞从质外体中吸收磷与叶片的磷输出相关;在磷饥饿胁迫下,成熟叶片通过木质部输入的磷明显减少,而通过韧皮部输出的磷相对增加。基于上述结果,本研究认为,在缺磷状况下玉米成熟叶的细胞显著增强磷吸收能力,可能有利于从叶片质外体包括木质部中吸收磷,并对增加叶的磷输出具有意义。

Phosphate uptake by plasma membrane vesicles was studied with ^32P labeled phosphate and the results indicated that phosphate uptake capacity （Vmax） of cells of maize （Zea mays L. ） mature leaf was enlarged （P 〈 0.01） under phosphorus starvation. Local application of ^32P labeled phosphate solutions on mature leaf revealed that a close relationship existed between phosphate uptake by leaf cells from the apoplasts and phosphorus export of the leaf. Furthermore, the investigation on variations of phosphorus contents in the xylem saps and phloem exudates of mature leaf during phosphorus starvation showed that phosphorus which was imported to mature leaf through xylem flows decreased markedly, while the phosphorus export of the leaf through phloem was enhanced relatively. It is proposed that enhancement of phosphate uptake capacity of cells of maize mature leaf under phosphorus deficiency might benefit the absorption of phosphate from leaf apoplasts including xylem and P output of mature leaf.