Phosphorus and aluminum interactions in soybean in relation to aluminum tolerance, exudation of specific organic acids from different regions of the intact root system
Phosphorus and aluminum interactions in soybean in relation to aluminum tolerance, exudation of specific organic acids from different regions of the intact root system
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DOI：
10.1104/pp.105.076497
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发表时间：
2006-06-01
期刊：
影响因子：
7.4
通讯作者：
Kochian, Leon V.
中科院分区：
文献类型：
--
作者：
Liao, Hong;Wan, Huiyan;Kochian, Leon V.
铝 (Al) 毒性和磷 (P) 缺乏通常在酸性土壤中同时存在，严重限制了作物的生长和产量，包括大豆 (Glycine max)。了解与植物铝和磷相互作用相关的生理机制应有助于促进耐铝和/或磷效率更高的作物的开发。本研究通过均质和异质营养液实验来研究Al和P相互作用对大豆根系生长和根系有机酸分泌的影响。在本体溶液中铝和磷分布均匀的均质溶液实验中，磷的添加显着提高了四种磷效率不同的大豆基因型的铝耐受性。在这些高磷条件下，两种高效磷基因型似乎比两种高效磷基因型更耐受铝。根部分泌物分析表明，铝中毒诱导柠檬酸盐渗出，磷缺乏引发草酸盐渗出，两种处理均诱导苹果酸释放。为了更接近地模拟低磷酸性土壤，其中磷缺乏和铝毒性通常在较低土壤层中更大，采用分开的根室/营养液方法在模拟的上部土壤层中施加升高的磷条件，并在较低层中施加铝毒性/磷缺乏。在这些条件下，我们发现两种磷效率高的基因型在实验的早期阶段比磷效率低的品系具有更高的铝耐受性。尽管在分室实验中根部渗出相同的三种有机酸，但其渗出模式与均质溶液体系中的渗出模式不同。两种磷高效基因型从主根尖分泌更多的苹果酸，这表明改善磷营养可能会增强铝毒性最大的根部区域有机酸的渗出，从而增强铝耐受性。这些发现表明磷效率可能在大豆耐铝性中发挥作用。高效磷基因型不仅可以通过直接的铝-磷相互作用，还可以通过与刺激特定根和根区域中不同铝螯合有机酸的渗出相关的间接相互作用来增强铝耐受性。
Aluminum (Al) toxicity and phosphorus (P) deficiency often coexist in acid soils that severely limit crop growth and production, including soybean (Glycine max). Understanding the physiological mechanisms relating to plant Al and P interactions should help facilitate the development of more Al-tolerant and/or P-efficient crops. In this study, both homogeneous and heterogeneous nutrient solution experiments were conducted to study the effects of Al and P interactions on soybean root growth and root organic acid exudation. In the homogenous solution experiments with a uniform Al and P distribution in the bulk solution, P addition significantly increased Al tolerance in four soybean genotypes differing in P efficiency. The two P-efficient genotypes appeared to be more Al tolerant than the two P-inefficient genotypes under these high-P conditions. Analysis of root exudates indicated Al toxicity induced citrate exudation, P deficiency triggered oxalate exudation, and malate release was induced by both treatments. To more closely mimic low-P acid soils where P deficiency and Al toxicity are often much greater in the lower soil horizons, a divided root chamber/nutrient solution approach was employed to impose elevated P conditions in the simulated upper soil horizon, and Al toxicity/P deficiency in the lower horizon. Under these conditions, we found that the two P-efficient genotypes were more Al tolerant during the early stages of the experiment than the P-inefficient lines. Although the same three organic acids were exuded by roots in the divided chamber experiments, their exudation patterns were different from those in the homogeneous solution system. The two P-efficient genotypes secreted more malate from the taproot tip, suggesting that improved P nutrition may enhance exudation of organic acids in the root regions dealing with the greatest Al toxicity, thus enhancing Al tolerance. These findings demonstrate that P efficiency may play a role in Al tolerance in soybean. Phosphorus-efficient genotypes may be able to enhance Al tolerance not only through direct Al-P interactions but also through indirect interactions associated with stimulated exudation of different Al-chelating organic acids in specific roots and root regions.