title: Analysis of transcriptional regulation and tissue-specific expression of Avicennia marina Plasma Membrane Protein 3 suggests it contributes to Na(+) transport and homoeostasis in A. marina.
abstract: Plasma membrane proteins (PMP3) play a role in cation homoeostasis. The 5' flanking sequence of stress inducible, Avicennia marina PMP3 (AmPMP3prom) was transcriptionally fused to (a) GUS or (b) GFP-AmPMP3 and analyzed in transgenic tobacco. Tissue-histochemical GUS and GFP:AmPMP3 localization are co-incident under basal and stress conditions. AmPMP3prom directed GUS activity is highest in roots. Basal transcription is conferred by a 388bp segment upstream of the translation start site. A 463bp distal enhancer in the AmPMP3prom confers enhanced expression under salinity in all tissues and also responds to increases in salinity. The effect of a central, stem-specific negative regulatory region is suppressed by the distal enhancer. The A. marina rhizosphere encounters dynamic changes in salinity at the inter-tidal interface. The complex, tissue-specific transcriptional responsiveness of AmPMP3 to salinity appears to have evolved in response to these changes. Under salinity, guard cell and phloem-specific expression of GFP:AmPMP3 is highly enhanced. Mesophyll, trichomes, bundle sheath, parenchymatous cortex and xylem parenchyma also show GFP:AmPMP3 expression. Cis-elements conferring stress, root and vascular-specific expression are enriched in the AmPMP3 promoter. Pronounced vascular-specific AmPMP3 expression suggests a role in salinity induced Na(+) transport, storage, and secretion in A. marina.
authors.affiliation: Department of Plant Molecular Biology, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, India 600 113. Electronic address: raji.rc@gmail.com.
authors.forename: Rajalakshmi
authors.initials: R
authors.lastname: Chidambaram
authors.affiliation: Department of Plant Molecular Biology, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, India 600 113. Electronic address: gayatri@mssrf.res.in.
authors.forename: Gayatri
authors.initials: G
authors.lastname: Venkataraman
authors.affiliation: Department of Plant Molecular Biology, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, India 600 113. Electronic address: ajay@mssrf.res.in.
authors.forename: Ajay
authors.initials: A
authors.lastname: Parida
mesh_terms: D000595:Amino Acid Sequence; D032407:Avicennia / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D054712:Salinity; D016415:Sequence Alignment; D012964:Sodium / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins; D012964:Sodium
keywords: Deletion analysis; Enhancer; Mangrove; PMP3; Salinity; Transgenic tobacco