Phosphate transport by proteoid roots of Hakea sericea

详细信息	查看全文 | 推荐本文 |

• 作者：Manuel Fern ; o Sousa ; Arnoldo Rocha Faç ; anha ; Rui Manuel Tavares ; Teresa Lino-Neto ; Hernâ ; ni Geró ; s
• 关键词：Hakea sericea ; Invasive species ; Phosphate uptake ; Phosphorus-poor soils ; Proteaceae ; Proteoid roots
• 刊名：Plant Science
• 出版年：2007
• 期刊代码：88_01689452
• 类别：abs
• 出版时间：November 2007
• 卷：173
• 期：5
• 页码：550-558
• 文件大小：547 K

摘要

Up to now the higher capacity of proteoid roots to absorb inorganic phosphate from P_i-poor soils has been related mainly to their increased root surface area and higher exudation of organic acids and phosphatases, while much less attention has been directed to their mechanisms of P_i uptake. Here we report a characterization of the P_i uptake kinetics of the proteoid root-forming species Hakea sericea Schrad. This Proteaceae is an Australian native, which is disseminating very fast through forests of the European south. Dense mats of proteoid roots were observed in the upper soil layers of the invaded area in Portugal where availability of P and N was shown to be very low. Plants grown hydroponically under low-P_i also developed proteoid roots, and the proteoid clusters presented a major role in P_i absorption in comparison to the non-proteoid portions of the root system as revealed by their higher ³²P_i labeling. The ³²P_i uptake by proteoid roots was dependent on H⁺ gradient and yielded a biphasic kinetics, suggesting the involvement of H⁺/P_i co-transport systems with K_m values of 0.225 and 40.8 μM P_i. The analogs phosphite (Phi) and arsenate, but not vanadate, inhibited competitively the P_i absorption. Such biphasic P_i uptake pattern with the highest affinity at submicromolar range is likely to be of critical importance for the capacity of this plant species to invade and proliferate throughout vast areas of nutrient-deprived soils.