Integrative Comparison of the Role of the PHOSPHATE RESPONSE1 Subfamily in Phosphate Signaling and Homeostasis in Rice
Integrative Comparison of the Role of the PHOSPHATE RESPONSE1 Subfamily in Phosphate Signaling and Homeostasis in Rice
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DOI：
10.1104/pp.15.00736
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发表时间：
2015-08-01
期刊：
影响因子：
7.4
通讯作者：
Mo, Xiaorong
中科院分区：
文献类型：
--
作者：
Guo, Meina;Ruan, Wenyuan;Mo, Xiaorong
磷（P）是所有活细胞必需的大量营养素，是农业生产不可缺少的。虽然拟南芥（Arabidopsis thaliana）PHOSPHATE RESPONSE 1（PHR 1）及其在其他物种中的直向同源物已被证明在磷酸盐（Pi）信号传导和Pi稳态的转录调节中起作用，但以前没有报道过水稻（Oryza sativa）中PHR 1相关蛋白的整合比较。在这里，我们确定了三个PHR 1同源基因在水稻（OsPHR 1，OsPHR 2和OsPHR 3）使用系统发育和突变分析的功能冗余。OsPHR 3与OsPHR 1和OsPHR 2一起在大多数Pi饥饿诱导基因的转录激活中起作用。这些转录因子（TF）中的任何一种功能丧失突变都会损害根毛生长（主要是根毛伸长）。然而，这三个TF在不同的组织和生长阶段的DNA结合亲和力和信使RNA表达模式的差异，和转录组学分析显示差异影响Pi饥饿诱导的基因表达的单一突变体的三个TF，表明一定程度的功能多样化。过量表达编码这些TF的基因导致部分组成型激活的Pi饥饿反应，并导致Pi积累在地上部。此外，与OsPHR 2过表达株系在正常或Pi缺乏条件下表现出生长迟缓不同，OsPHR 3过表达植株表现出对低Pi胁迫的显著耐受性，但在正常Pi条件下表现出正常生长速率，这表明OsPHR 3将可用于分子育种以改善Pi缺乏条件下的Pi吸收/利用效率。我们认为OsPHR 1、OsPHR 2和OsPHR 3在水稻中形成一个网络，在调节Pi信号和体内平衡中发挥不同的作用。
Phosphorus (P), an essential macronutrient for all living cells, is indispensable for agricultural production. Although Arabidopsis (Arabidopsis thaliana) PHOSPHATE RESPONSE1 (PHR1) and its orthologs in other species have been shown to function in transcriptional regulation of phosphate (Pi) signaling and Pi homeostasis, an integrative comparison of PHR1-related proteins in rice (Oryza sativa) has not previously been reported. Here, we identified functional redundancy among three PHR1 orthologs in rice (OsPHR1, OsPHR2, and OsPHR3) using phylogenetic and mutation analysis. OsPHR3 in conjunction with OsPHR1 and OsPHR2 function in transcriptional activation of most Pi starvation-induced genes. Loss-of-function mutations in any one of these transcription factors (TFs) impaired root hair growth (primarily root hair elongation). However, these three TFs showed differences in DNA binding affinities and messenger RNA expression patterns in different tissues and growth stages, and transcriptomic analysis revealed differential effects on Pi starvation-induced gene expression of single mutants of the three TFs, indicating some degree of functional diversification. Overexpression of genes encoding any of these TFs resulted in partial constitutive activation of Pi starvation response and led to Pi accumulation in the shoot. Furthermore, unlike OsPHR2-overexpressing lines, which exhibited growth retardation under normal or Pi-deficient conditions, OsPHR3-overexpressing plants exhibited significant tolerance to low-Pi stress but normal growth rates under normal Pi conditions, suggesting that OsPHR3 would be useful for molecular breeding to improve Pi uptake/use efficiency under Pi-deficient conditions. We propose that OsPHR1, OsPHR2, and OsPHR3 form a network and play diverse roles in regulating Pi signaling and homeostasis in rice.