Department of Biology, Faculty of Science, Golsatan University, PO Box 155, Gorgan 49138-15739, Iran.
Ann Bot. 2010 Mar;105(3):365-74. doi: 10.1093/aob/mcp297. Epub 2009 Dec 25.
In some lupin species, phosphate deficiency induces cluster-root formation, which enhances P uptake by increasing root surface area and, more importantly, the release of root exudates which enhances P availability.
Three species of Lupinus, L. albus, L. atlanticus and L. micranthus, with inherently different relative growth rates were cultivated under hydroponics in a greenhouse at four phosphate concentrations (1, 10, 50 and 150 microm) to compare the role of internal P in regulating cluster-root formation.
The highest growth rate was observed in L. atlanticus, followed by L. albus and L. micranthus. At 1 microm P, cluster-root formation was markedly induced in all three species. The highest P uptake and accumulation was observed in L. micranthus, followed by L. atlanticus and then L. albus. Inhibition of cluster-root formation was severe at 10 microm P in L. atlanticus, but occurred stepwise with increasing P concentration in the root medium in L. albus.
In L. atlanticus and L. albus cluster-root formation was suppressed by P treatments above 10 microm, indicating a P-inducible regulating system for cluster-root formation, as expected. By contrast, production of cluster roots in L. micranthus, in spite of a high internal P concentration, indicated a lower sensitivity to P status, which allowed P-toxicity symptoms to develop.
在某些羽扇豆属物种中，磷酸盐缺乏会诱导簇生根的形成，这通过增加根表面积，更重要的是，通过释放根分泌物来增强磷的可用性，从而增强磷的吸收。
在温室水培条件下，以四种磷酸盐浓度（1、10、50 和 150 µm）培养三种羽扇豆属植物（L. albus、L. atlanticus 和 L. micranthus），比较内部磷在调节簇生根形成中的作用。
L. atlanticus 的相对生长率最高，其次是 L. albus 和 L. micranthus。在 1 µm P 下，三种植物都明显诱导了簇生根的形成。L. micranthus 的磷吸收和积累最高，其次是 L. atlanticus，然后是 L. albus。在 10 µm P 下，L. atlanticus 的簇生根形成受到严重抑制，但在根介质中 P 浓度增加时，L. albus 的抑制作用呈逐步增加的趋势。
在 L. atlanticus 和 L. albus 中，P 处理浓度高于 10 µm 时抑制了簇生根的形成，表明簇生根形成存在 P 诱导的调节系统，这是预期的。相比之下，尽管 L. micranthus 内部 P 浓度较高，但簇生根的产生表明其对 P 状况的敏感性较低，这允许出现 P 毒性症状。
