Stimulation of phosphorus uptake by ammonium nutrition involves plasma membrane H+ ATPase in rice roots
Stimulation of phosphorus uptake by ammonium nutrition involves plasma membrane H+ ATPase in rice roots
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DOI：
10.1007/s11104-012-1136-4
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发表时间：
2012-02
期刊：
影响因子：
4.9
通讯作者：
Houqing Zeng;Gan Liu;T. Kinoshita;Ruiping Zhang;Yiyong Zhu;Q. Shen;Guohua Xu
中科院分区：
文献类型：
--
作者：
Houqing Zeng;Gan Liu;T. Kinoshita;Ruiping Zhang;Yiyong Zhu;Q. Shen;Guohua Xu
氮素，尤其是NH 4+，可以促进植物对磷的吸收，但其作用机制尚不清楚。由于磷酸盐是通过阴离子/H+共运输过程，我们建议，刺激吸收的磷NH 4+与NO3-营养可能与质膜H+ ATP酶的活性。在本研究中，我们研究了NH 4+和NO3-对水稻磷吸收和质膜H+ ATP酶活性的影响。培养15天后，测定磷含量。采用两相分离法分离根质膜，水解30 min后测定质膜的Pi浓度，测定水解H+-ATPase活性。通过实时定量逆转录聚合酶链反应（qRT-PCR）分析质膜H+ ATP酶基因的相对表达。Western blot法检测质膜H+ ATP酶浓度。结果添加NH 4+的水稻根和地上部的P含量均显著高于添加NO3-的水稻。NH_4 ~+胁迫下水稻根系质膜H ~+ATPase活性显著高于NO_3 ~-胁迫下的水稻根系。荧光定量PCR和western blot结果表明，NH 4+胁迫下水稻根系质膜H+ ATP酶活性的提高可能是由于OSA 1、OSA 3、OSA 7、OSA 8和OSA 9基因的表达增加以及质膜H+ ATP酶浓度的增加。33 P吸收实验结果表明，在培养4小时内，NH 4+培养的水稻根系吸收的33 P比NO 3-培养的多。钒酸盐抑制了NH 4+胁迫下水稻根系对33 P的吸收，而在NO3-胁迫下则促进了水稻根系对33 P的吸收。结论质膜H+ATPase参与了NH 4+胁迫下水稻根系对33 P的吸收。
AimsNitrogen, especially NH4+, can stimulate the uptake of phosphorus in plants, but the underlying mechanisms have not been clearly elucidated. Because phosphate is taken up via an anion/H+co-transport process, we propose that the stimulated uptake of phosphorus by NH4+versus NO3-nutrition may be related to the activity of plasma membrane H+ATPase. In the present study, we investigated the effect of NH4+and NO3-on phosphorus uptake and plasma membrane H+ATPase activity in rice.MethodsRice plants were cultivated in a hydroponic solution with NH4+or NO3-. After 15 days of cultivation, phosphorus content was determined. Root plasma membrane was isolated using a two-phase partitioning system and hydrolytic H+-ATPase activity was determined by measuring the Piconcentration after a 30-min hydrolysis reaction. Relative expression of plasma membrane H+ATPase genes was analyzed by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). H+ATPase enzyme concentration in the plasma membrane was detected by western blot. For33P uptake experiments, rice roots were incubated in the nutrient solution with addition of H333PO4.ResultsP content in both the roots and shoots of rice plants supplemented with NH4+was significantly higher than P content in plants grown with NO3-. Plasma membrane H+ATPase activity in NH4+-fed rice roots was significantly higher than that in NO3--fed rice roots. Real-time qRT-PCR and western blot results indicated that the higher activity of plasma membrane H+ATPase in NH4+-fed rice roots could be attributed to increased expression of theOSA1,OSA3,OSA7,OSA8andOSA9genes and an increase in H+ATPase enzyme concentration in the plasma membrane. Results from33P uptake experiments showed that rice roots incubated with NH4+absorbed more33P during the four-hour incubation than did rice roots incubated with NO3-. Vanadate inhibited33P uptake in rice roots supplied with NH4+, while fusicoccin stimulated33P uptake under NO3-nutrition.ConclusionsTaken together, these results suggest an involvement of plasma membrane H+ATPase in the stimulated uptake of phosphorus by rice roots supplemented with NH4+.