LEAF TIP NECROSIS1 Plays a Pivotal Role in the Regulation of Multiple Phosphate Starvation Responses in Rice
LEAF TIP NECROSIS1 Plays a Pivotal Role in the Regulation of Multiple Phosphate Starvation Responses in Rice
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DOI：
10.1104/pp.110.170209
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发表时间：
2011-07-01
期刊：
影响因子：
7.4
通讯作者：
Chu, Chengcai
中科院分区：
文献类型：
--
作者：
Hu, Bin;Zhu, Chenguang;Chu, Chengcai
虽然磷（Pi）饥饿信号在拟南芥（Arabidopsis thaliana）中得到了很好的研究，但在水稻（Oryza sativa）中仍然很大程度上未知。在这项工作中，水稻叶尖坏死1（ltn 1）突变体的鉴定和特征。图位克隆鉴定LTN 1为LOC_Os05g48390，其为拟南芥PHO 2的推定直向同源物，其在Pi饥饿信号传导中起重要作用。分析含有LTN 1启动子：：β-葡萄糖醛酸苷酶构建体的转基因植物显示，LTN 1优先在维管组织中表达。ltn 1突变体表现出增加的Pi吸收和转运，从而导致Pi在地上部的过度积累。与增强的Pi吸收和运输，一些Pi转运上调ltn 1突变体中存在足够的Pi。此外，在缺磷胁迫下，LTN 1突变体的初生根和不定根的伸长增强，表明LTN 1参与了磷依赖的根构型改变。在磷充足的条件下，典型的磷饥饿反应，如磷酸酶和核糖核酸酶活性的刺激，脂质组成的改变，氮同化抑制，增加金属吸收也被激活ltn 1。此外，对OsmiR 399过表达植物的分析表明，LTN 1被OsmiR 399下调。我们的研究结果有力地表明，LTN 1是一个关键的磷饥饿信号组件下游的miR 399参与调节多个磷饥饿反应在水稻。
Although phosphate (Pi) starvation signaling is well studied in Arabidopsis (Arabidopsis thaliana), it is still largely unknown in rice (Oryza sativa). In this work, a rice leaf tip necrosis1 (ltn1) mutant was identified and characterized. Map-based cloning identified LTN1 as LOC_Os05g48390, the putative ortholog of Arabidopsis PHO2, which plays important roles in Pi starvation signaling. Analysis of transgenic plants harboring a LTN1 promoter::beta-glucuronidase construct revealed that LTN1 was preferentially expressed in vascular tissues. The ltn1 mutant exhibited increased Pi uptake and translocation, which led to Pi overaccumulation in shoots. In association with enhanced Pi uptake and transport, some Pi transporters were up-regulated in the ltn1 mutant in the presence of sufficient Pi. Furthermore, the elongation of primary and adventitious roots was enhanced in the ltn1 mutant under Pi starvation, suggesting that LTN1 is involved in Pi-dependent root architecture alteration. Under Pi-sufficient conditions, typical Pi starvation responses such as stimulation of phosphatase and RNase activities, lipid composition alteration, nitrogen assimilation repression, and increased metal uptake were also activated in ltn1. Moreover, analysis of OsmiR399-overexpressing plants showed that LTN1 was down-regulated by OsmiR399. Our results strongly indicate that LTN1 is a crucial Pi starvation signaling component downstream of miR399 involved in the regulation of multiple Pi starvation responses in rice.