背景回顾：The coordinated distribution of inorganic phosphate (Pi) between roots and shoots is an important process that plants use to maintain Pi homeostasis. SHORT-ROOT (SHR) is well characterized for its function in root radial patterning. 

主要发现：Here we demonstrate a role of SHR in controlling Pi allocation from root to shoot by regulating PHOSPHATE1 in the root differentiation zone. 

结果1-SHR功能：We recovered a weak mutant allele of SHR in Arabidopsis that accumulates much less Pi in the shoot and shows a constitutive Pi starvation response under Pi-sufficient conditions.  

结果2-磷饥饿-SHR-PHB：In addition, Pi starvation suppresses SHR protein accumulation and releases its inhibition on the HD–ZIP III transcription factor PHB. 

结果3-PHB-PHO2-PHO1：PHB accumulates and directly binds the promoter of PHOSPHATE2 to upregulate its transcription, resulting in PHOSPHATE1 degradation in the xylem-pole pericycle cells.

结论：Our findings reveal a previously unrecognized mechanism of how plants regulate Pi translocation from roots to shoots.

 摘 要 

植物地上和地下组织之间无机磷（Pi）的协调分布对于植物维持Pi稳态至关重要。SHR是一个作用于植物根径向模式建立的关键基因。本文中，作者发现SHR通过调节根分化区的PHO1，作用于Pi从地下组织往地上组织的分配。作者构建了一个SHR功能部分恢复的突变体，发现其地上部分积累的Pi较少，并且在Pi充足的情况下表现出组成型的Pi饥饿响应。此外，Pi饥饿会抑制SHR蛋白积累，并释放其对HD–ZIP III转录因子PHB的抑制。随后，PHB蛋白积累，并直接结合PHO2基因的启动子以上调该基因的表达，导致木质部极中柱鞘细胞中PHO1蛋白的降解。本文的研究结果揭示了一种以前未知分子机制，控制植物从地下到地上组织的Pi转运。

 雷明光