title: LEAF TIP NECROSIS1 plays a pivotal role in the regulation of multiple phosphate starvation responses in rice.
abstract: 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::β-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.
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
authors.forename: Chenguang
authors.initials: C
authors.lastname: Zhu
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.forename: Jiuyou
authors.initials: J
authors.lastname: Tang
authors.forename: Yiqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Aihong
authors.initials: A
authors.lastname: Lin
authors.forename: Linchuan
authors.initials: L
authors.lastname: Liu
authors.forename: Ronghui
authors.initials: R
authors.lastname: Che
authors.forename: Chengcai
authors.initials: C
authors.lastname: Chu
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D001692:Biological Transport; D003001:Cloning, Molecular; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D035683:MicroRNAs / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009566:Nitrates / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010710:Phosphates / Q000172:deficiency* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012260:Ribonucleases / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D008055:Lipids; D035683:MicroRNAs; D009566:Nitrates; D010710:Phosphates; D010940:Plant Proteins; D025801:Ubiquitin; D007501:Iron; D012260:Ribonucleases; D000135:Acid Phosphatase