title: The soybean mycorrhiza-inducible phosphate transporter gene, GmPT7, also shows localized expression at the tips of vein endings of senescent leaves.
abstract: GmPT7 was originally identified as an arbuscular mycorrhiza-inducible gene of soybean that encodes a member of subfamily I in the PHOSPHATE TRANSPORTER 1 family. In the present study, we established conditions under which a number of dwarf soybean plants complete their life cycles in a growth chamber. Using this system, we grew transgenic soybean with a GmPT7 promoter-β-glucuronidase fusion gene and evaluated GmPT7 expression in detail. GmPT7 was highly expressed in mature, but not in collapsed, arbuscule-containing cortical cells, suggesting its importance in the absorption of fungus-derived phosphate and/or arbuscule development. GmPT7 was also expressed in the columella cells of root caps and in the lateral root primordia of non-mycorrhizal roots. The expression of GmPT7 occurred only in the late stage of phosphorus translocation from leaves to seeds, after water evaporation from the leaves ceased, and later than the expression of GmUPS1-2, GmNRT1.7a and GmNRT1.7b, which are possibly involved in nitrogen export. GmPT7 expression was localized in a pair of tracheid elements at the tips of vein endings of senescent leaves. Transmission electron microscopy revealed that the tip tracheid elements in yellow leaves were still viable and had intact plasma membranes. Thus, we think that GmPT7 on the plasma membranes transports phosphate from the apoplast into the tip elements. GmPT7 knockdown resulted in no significant effects, the function of GmPT7 remaining to be clarified. We propose a working model in which phosphate incorporated in vein endings moves to seeds via xylem to phloem transfer.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657 Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kobae
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Omoto
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Banba
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Takai
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: NARO Hokkaido Agricultural Research Center, Hitsujigaoka, Sapporo, 062-0081 Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Hirose
authors.affiliation: NARO Hokkaido Agricultural Research Center, Hitsujigaoka, Sapporo, 062-0081 Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Shungo
authors.initials: S
authors.lastname: Otagaki
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Matsumoto
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo, 060-8589 Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Masuta
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602 Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Ishimoto
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan Ryukoku University, Fushimi-ku, Kyoto, 612-8577 Japan shing@agr.ryukoku.ac.jp.
authors.forename: Shingo
authors.initials: S
authors.lastname: Hata
mesh_terms: D016922:Cellular Senescence; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D038821:Mycorrhizae / Q000235:genetics* / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D052585:Phloem / Q000235:genetics / Q000382:microbiology; D028061:Phosphate Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D013025:Glycine max / Q000235:genetics* / Q000382:microbiology; D013559:Symbiosis
chemical_list: D028061:Phosphate Transport Proteins; D010710:Phosphates; D010940:Plant Proteins; D009584:Nitrogen
keywords: Arbuscular mycorrhiza; Dwarfing; Glycine max L. Merrill; Leaf senescence; Phosphate transporter; Vein ending