LEAF TIP NECROSIS 1 Plays a Pivotal Role in Regulation of Multiple Phosphate Starvation Responses in Rice
| 作者： |
Bin Hu,Chengguang Zhu,Feng Li,Jiuyou Tang,Yiqin Wang,Aihong Lin,Linchuan Liu,Ronghui Che and Chengcai Chu |
| 刊物名称： |
Plant Physiology |
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| 发表年度： |
2011-02-12 |
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| 摘要： |
Although phosphate (Pi) starvation signaling is well studied in Arabidopsis, it is still largely unknown in rice. 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:: GUS construct revealed that LTN1 was preferentially expressed in vascular tissues. The ltn1 mutant exhibited increased Pi uptake and translocation, which lead to Pi over-accumulation 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 ribonuclease activities, lipid composition alteration, nitrogen assimilation repression, and increased metal uptake were also activated in ltn1. Moreover, analysis of OsmiR399 over-expressing 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. |
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