Allocation of foliar phosphorus fractions and leaf traits of tropical tree species in response to decreased soil phosphorus availability on Mount Kinabalu, Borneo
Allocation of foliar phosphorus fractions and leaf traits of tropical tree species in response to decreased soil phosphorus availability on Mount Kinabalu, Borneo
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DOI：
10.1111/j.1365-2745.2011.01805.x
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发表时间：
2011-05-01
影响因子：
5.5
通讯作者：
Kitayama, Kanehiro
中科院分区：
文献类型：
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作者：
Hidaka, Amane;Kitayama, Kanehiro
P>；1.叶磷(P)浓度是细胞中磷组分，如无机磷和各种含磷生化化合物(如核酸、脂类和糖磷酸盐)的浓度之和。植物一般会降低叶片中的磷浓度，提高磷的利用效率，以应对土壤磷有效性低的情况。然而，植物如何在叶片磷组分中分配磷以降低叶片磷浓度仍不清楚。我们研究了婆罗洲基纳巴卢山上三个热带山地雨林中21种热带树种沿土壤磷有效性梯度的叶片磷组分和叶片特征。我们按化学顺序将叶片P分成以下四个组分：结构P(即磷脂)、代谢P(统称为PI、ATP和糖磷酸盐)、核酸P和残留P(磷蛋白和未知残基)。随着土壤磷有效性的降低，叶片磷浓度降低，单位面积叶质量(LMA)增大。叶面磷浓度的下降与代谢磷和核酸磷浓度的下降密切相关，虽然增加的LMA意味着增加了对结构组织的分配，但随着LMA的增加，代谢P和结构P之间的分配没有权衡。这表明，贫磷土壤上的热带树种增加了叶片的韧性(即延长了叶片的寿命)，并在不增加结构组织磷的成本的情况下保持了较高的光合磷利用效率(PPUE)。土壤磷再吸收效率随土壤磷有效性的降低而增加。在缺磷土壤上，叶片脱落前吸收的磷的量超过了代谢磷的量，这表明热带树种在代谢的同时，还通过提取固定组分(即核酸P和结构磷)来实现高的磷再吸收效率。综合。我们的结论是，贫磷土壤上的树种通过降低代谢磷和核酸磷的浓度来减少对叶片磷的需求，这可能会潜在地限制生长和生产力。然而，这些树种能够保持较高的全株磷利用效率，因为这种对叶磷组分的反应不会降低PPUE、叶片寿命和磷再吸收效率。
P>1. Foliar phosphorus (P) concentration is the sum of the concentrations of P fractions in cells, such as inorganic P and various P-containing biochemical compounds (e.g. nucleic acids, lipids and sugar phosphates). Plants generally reduce foliar P concentration and enhance P-use efficiency in response to low soil P availability. However, how plants allocate P among foliar P fractions to reduce foliar P concentration remains unclear.2. We investigated foliar P fractions and leaf traits of 21 tropical tree species along a soil P availability gradient across three tropical montane rain forests on Mount Kinabalu, Borneo. We chemically and sequentially fractionated foliar P into the following four fractions: structural P (i.e. phospholipids), metabolic P (collectively including Pi, ATP and sugar phosphates), nucleic acid P and residual P (phosphoproteins and unidentified residue).3. With decreasing soil P availability, foliar P concentration decreased and leaf mass per area (LMA) increased. The reduction in foliar P concentration strongly correlated with the reduction in the concentrations of both metabolic P and nucleic acid P. Although increased LMA implies an increased allocation to structural tissues, there was no trade-off in P allocation between metabolic P and structural P with increasing LMA. This suggests that tropical tree species on P-poor soils increase the toughness of leaves (i.e. prolonged leaf life span) and also maintain high photosynthetic P-use efficiency (PPUE) without increasing the cost of P for structural tissues.4. Phosphorus resorption efficiency increased with decreasing soil P availability. The amount of P resorbed before leaf abscission on P-poor soils exceeded that of metabolic P. This suggests that tropical tree species achieve the high P resorption efficiency by withdrawing immobile fractions (i.e. nucleic acid P and structural P) in addition to metabolic P.5. Synthesis. We conclude that tree species on P-poor soils reduce the demand for foliar P by reducing concentrations of both metabolic P and nucleic acid P, which may potentially limit growth and productivity. However, these tree species can maintain high whole-plant P-use efficiency, because such responses in foliar P fractions do not decrease PPUE, leaf life span and P resorption efficiency.