title: The tomato plastidic fructokinase SlFRK3 plays a role in xylem development.
abstract: Plants have two kinds of fructokinases (FRKs) that catalyze the key step of fructose phosphorylation, cytosolic and plastidic. The major cytosolic tomato FRK, SlFRK2, is essential for the development of xylem vessels. In order to study the role of SlFRK3, which encodes the only plastidic FRK, we generated transgenic tomato (Solanum lycopersicon) plants with RNAi suppression of SlFRK3 as well as plants expressing beta-glucoronidase (GUS) under the SlFRK3 promoter. GUS staining indicated SlFRK3 expression in vascular tissues of the leaves and stems, including cambium, differentiating xylem, young xylem fibers and phloem companion cells. Suppression of SlFRK3 reduced the stem xylem area, stem and root water conductance, and whole-plant transpiration, with minor effects on plant development. However, suppression of SlFRK3 accompanied by partial suppression of SlFRK2 induced significant growth-inhibition effects, including the wilting of mature leaves. Grafting experiments revealed that these growth effects are imposed primarily by the leaves, whose petioles had unlignified, thin-walled xylem fibers with collapsed parenchyma cells around the vessels. A cross between the SlFRK2-antisense and SlFRK3-RNAi lines exhibited similar wilting and anatomical effects, confirming that these effects are the result of the combined suppression of SlFRK3 and SlFRK2. These results demonstrate a role of the plastidic SlFRK3 in xylem development and hydraulic conductance.
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.|The Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Stein
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
authors.forename: Hila
authors.initials: H
authors.lastname: Damari-Weissler
authors.affiliation: Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Secchi
authors.affiliation: Albert Katz Department of Dryland Biotechnologies, Blaustein Institutes for Desert Research, Ben Gurion University, Sede Boqer Campus, 84990, Israel.
authors.forename: Shimon
authors.initials: S
authors.lastname: Rachmilevitch
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: German
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
authors.forename: Yelena
authors.initials: Y
authors.lastname: Yeselson
authors.affiliation: Laboratory of Plant Science, Migal Galilee Research Center, PO Box 831, Kiryat Shmona, 12100, Israel.
authors.forename: Rachel
authors.initials: R
authors.lastname: Amir
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
authors.forename: Arthur
authors.initials: A
authors.lastname: Schaffer
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., Cambridge, MA, 02138, USA.
authors.forename: N Michele
authors.initials: NM
authors.lastname: Holbrook
authors.affiliation: Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Roni
authors.initials: R
authors.lastname: Aloni
authors.affiliation: Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
authors.forename: Maciej A
authors.initials: MA
authors.lastname: Zwieniecki
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Granot
mesh_terms: D001692:Biological Transport; D018533:Biomass; D035264:Flowers / Q000502:physiology; D005631:Fructokinases / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D010641:Phenotype; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D018547:Plant Stems / Q000378:metabolism; D018526:Plant Transpiration / Q000502:physiology; D030821:Plants, Genetically Modified; D018087:Plastids / Q000201:enzymology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012995:Solubility; D014867:Water; D052584:Xylem / Q000201:enzymology* / Q000502:physiology
chemical_list: D010940:Plant Proteins; D014867:Water; D005631:Fructokinases; C046173:fructokinase
keywords: RNAi; fructokinase; fructose; plastid; sucrose; tomato (Solanum lycopersicon); xylem fiber; xylem vessel