title: Phosphorus remobilization from rice flag leaves during grain filling: an RNA-seq study.
abstract: The physiology and molecular regulation of phosphorus (P) remobilization from vegetative tissues to grains during grain filling is poorly understood, despite the pivotal role it plays in the global P cycle. To test the hypothesis that a subset of genes involved in the P starvation response are involved in remobilization of P from flag leaves to developing grains, we conducted an RNA-seq analysis of rice flag leaves during the preremobilization phase (6 DAA) and when the leaves were acting as a P source (15 DAA). Several genes that respond to phosphate starvation, including three purple acid phosphatases (OsPAP3, OsPAP9b and OsPAP10a), were significantly up-regulated at 15 DAA, consistent with a role in remobilization of P from flag leaves during grain filling. A number of genes that have not been implicated in the phosphate starvation response, OsPAP26, SPX-MFS1 (a putative P transporter) and SPX-MFS2, also showed expression profiles consistent with involvement in P remobilization from senescing flag leaves. Metabolic pathway analysis using the KEGG system suggested plastid membrane lipid synthesis is a critical process during the P remobilization phase. In particular, the up-regulation of OsPLDz2 and OsSQD2 at 15 DAA suggested phospholipids were being degraded and replaced by other lipids to enable continued cellular function while liberating P for export to developing grains. Three genes associated with RNA degradation that have not previously been implicated in the P starvation response also showed expression profiles consistent with a role in P mobilization from senescing flag leaves.
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.|Southern Cross GeoScience, Southern Cross University, Lismore, NSW, Australia.
authors.forename: Kwanho
authors.initials: K
authors.lastname: Jeong
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.
authors.forename: Abdul
authors.initials: A
authors.lastname: Baten
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.
authors.forename: Daniel L E
authors.initials: DL
authors.lastname: Waters
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.|Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
authors.forename: Omar
authors.initials: O
authors.lastname: Pantoja
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.|Southern Cross GeoScience, Southern Cross University, Lismore, NSW, Australia.
authors.forename: Cecile C
authors.initials: CC
authors.lastname: Julia
authors.affiliation: Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wissuwa
authors.affiliation: University of Adelaide, School of Agriculture Food and Wine / Australian Centre for Plant Functional Genomics (ACPFG), Adelaide, SA, Australia.
authors.forename: Sigrid
authors.initials: S
authors.lastname: Heuer
authors.affiliation: Genotyping Services Laboratory, International Rice Research Institute (IRRI), Metro Manila, Philippines.
authors.forename: Tobias
authors.initials: T
authors.lastname: Kretzschmar
authors.affiliation: Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.|Southern Cross GeoScience, Southern Cross University, Lismore, NSW, Australia.
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Rose
mesh_terms: D000375:Aging; D001483:Base Sequence; D002874:Chromosome Mapping; D002523:Edible Grain / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D050356:Lipid Metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017423:Sequence Analysis, RNA / Q000379:methods*; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D010758:Phosphorus
keywords: 
  Oryza sativa
  ; Illumina sequencing; differential gene expression; phosphorus translocation; senescence