CEA, DSV, IBEB, Lab Biol Develop Plantes, CNRS, UMR 6191 Biol Veget & Microbiol Environ, Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France.
Plant J. 2010 Dec;64(5):775-89. doi: 10.1111/j.1365-313X.2010.04375.x. Epub 2010 Nov 2.
Phosphate is a crucial and often limiting nutrient for plant growth. To obtain inorganic phosphate (P(i) ), which is very insoluble, and is heterogeneously distributed in the soil, plants have evolved a complex network of morphological and biochemical processes. These processes are controlled by a regulatory system triggered by P(i) concentration, not only present in the medium (external P(i) ), but also inside plant cells (internal P(i) ). A 'split-root' assay was performed to mimic a heterogeneous environment, after which a transcriptomic analysis identified groups of genes either locally or systemically regulated by P(i) starvation at the transcriptional level. These groups revealed coordinated regulations for various functions associated with P(i) starvation (including P(i) uptake, P(i) recovery, lipid metabolism, and metal uptake), and distinct roles for members in gene families. Genetic tools and physiological analyses revealed that genes that are locally regulated appear to be modulated mostly by root development independently of the internal P(i) content. By contrast, internal P(i) was essential to promote the activation of systemic regulation. Reducing the flow of P(i) had no effect on the systemic response, suggesting that a secondary signal, independent of P(i) , could be involved in the response. Furthermore, our results display a direct role for the transcription factor PHR1, as genes systemically controlled by low P(i) have promoters enriched with P1BS motif (PHR1-binding sequences). These data detail various regulatory systems regarding P(i) starvation responses (systemic versus local, and internal versus external P(i) ), and provide tools to analyze and classify the effects of P(i) starvation on plant physiology.
磷酸盐是植物生长的关键且常受限制的营养物质。为了获取无机磷酸盐(P(i)),这种物质的溶解度非常低,而且在土壤中分布不均,植物进化出了一系列复杂的形态和生化过程。这些过程受由 P(i)浓度触发的调控系统控制,不仅存在于介质中(外部 P(i)),也存在于植物细胞内(内部 P(i))。通过“分根”实验模拟非均相环境,然后进行转录组分析,在转录水平上确定了受 P(i)饥饿局部或系统调控的基因群。这些基因群揭示了与 P(i)饥饿相关的各种功能的协调调控(包括 P(i)摄取、P(i)回收、脂质代谢和金属摄取),以及基因家族成员的不同作用。遗传工具和生理分析表明,局部调控的基因似乎主要通过根发育来调节,而与内部 P(i)含量无关。相比之下,内部 P(i)对于促进系统调节的激活是必不可少的。减少 P(i)的流动对系统反应没有影响,这表明一种独立于 P(i)的二次信号可能参与其中。此外,我们的结果显示转录因子 PHR1 具有直接作用,因为受低 P(i)系统调控的基因启动子富含 P1BS 基序(PHR1 结合序列)。这些数据详细描述了各种与 P(i)饥饿反应相关的调控系统(系统与局部、内部与外部 P(i)),并提供了分析和分类 P(i)饥饿对植物生理学影响的工具。