OsPHT1;3 Mediates Uptake, Translocation, and Remobilization of Phosphate under Extremely Low Phosphate Regimes
OsPHT1;3 Mediates Uptake, Translocation, and Remobilization of Phosphate under Extremely Low Phosphate Regimes
复制标题
水稻磷酸盐转运蛋白 OsPHT1;3 在极低磷酸盐条件下介导磷酸盐的吸收、转运和再动员
DOI：
10.1104/pp.18.01097
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发表时间：
2019-02-01
期刊：
影响因子：
7.4
通讯作者：
Xu, Guo Hua
中科院分区：
文献类型：
--
作者：
Chang, Ming Xing;Gu, Mian;Xu, Guo Hua
植物根部依靠无机正磷酸盐 (Pi) 转运蛋白从自然生态系统中以微摩尔水平存在的土壤溶液中获取可溶性 Pi。在这里，我们对水稻 (Oryza sativa) Pi 转运蛋白 Os 磷酸盐转运蛋白 1;3 (OsPHT1;3) 进行了功能表征，它介导 Pi 吸收、易位和再动员。 OsPHT1;3 直接受 Os 磷酸盐饥饿反应 2 调节，并且响应 Pi 饥饿，在幼叶和芽基部区域表现出增强的表达，在根和老叶片中表现更明显。 OsPHT1;3 能够补充五种 Pi 转运蛋白缺陷的酵母突变株，并介导非洲爪蟾卵母细胞中的 Pi 流入。 OsPHT1;3 的过度表达导致根和芽中 Pi 浓度增加。然而，与报道的其他已知的OsPHT1成员在相对较高的Pi水平下促进Pi吸收不同，OsPHT1;3的突变仅在外部Pi浓度低于5μM时才损害Pi吸收和从根到茎的Pi易位。此外，在基节中，OsPHT1;3的表达仅限于规则维管束和扩大的维管束的韧皮部。 P-32 的同位素标记实验表明，ospht1;3 突变株系在 Pi 从源叶到库叶的再动员过程中受到损害。此外，OsPHT1;3 的过度表达和突变导致 OsPHT1;2 和其他几个 OsPHT1 基因表达的相互改变。酵母双杂交、双分子荧光互补和免疫共沉淀测定均证明了 OsPHT1;3 和 OsPHT1;2 之间的物理相互作用。综上所述，我们的结果表明，在 Pi 水平极低的环境中生长的植物中，OsPHT1;3 对于 Pi 获取、根部到茎部的 Pi 易位和磷的重新分配起着关键因素的作用。
Plant roots rely on inorganic orthophosphate (Pi) transporters to acquire soluble Pi from soil solutions that exists at micromolar levels in natural ecosystems. Here, we functionally characterized a rice (Oryza sativa) Pi transporter, Os Phosphate Transporter1;3 (OsPHT1;3), that mediates Pi uptake, translocation, and remobilization. OsPHT1;3 was directly regulated by Os Phosphate Starvation Response-2 and, in response to Pi starvation, showed enhanced expression in young leaf blades and shoot basal regions and even more so in roots and old leaf blades. OsPHT1;3 was able to complement a yeast mutant strain defective in five Pi transporters and mediate Pi influx in Xenopus laevis oocytes. Overexpression of OsPHT1;3 led to increased Pi concentration both in roots and shoots. However, unlike that reported for other known OsPHT1 members that facilitate Pi uptake at relatively higher Pi levels, mutation of OsPHT1;3 impaired Pi uptake and root-to-shoot Pi translocation only when external Pi concentration was below 5 mu M. Moreover, in basal nodes, the expression of OsPHT1;3 was restricted to the phloem of regular vascular bundles and enlarged vascular bundles. An isotope labeling experiment with P-32 showed that ospht1;3 mutant lines were impaired in remobilization of Pi from source to sink leaves. Furthermore, overexpression and mutation of OsPHT1;3 led to reciprocal alteration in the expression of OsPHT1;2 and several other OsPHT1 genes. Yeast-two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays all demonstrated a physical interaction between OsPHT1;3 and OsPHT1;2. Taken together, our results indicate that OsPHT1;3 acts as a crucial factor for Pi acquisition, root-to-shoot Pi translocation, and redistribution of phosphorus in plants growing in environments with extremely low Pi levels.