title: Cloning, functional characterization and heterologous expression of TaLsi1, a wheat silicon transporter gene.
abstract: Silicon (Si) is known to be beneficial to plants, namely in alleviating biotic and abiotic stresses. The magnitude of such positive effects is associated with a plant's natural ability to absorb Si. Many grasses can accumulate as much as 10% on a dry weight basis while most dicots, including Arabidopsis, will accumulate less than 0.1%. In this report, we describe the cloning and functional characterization of TaLsi1, a wheat Si transporter gene. In addition, we developed a heterologous system for the study of Si uptake in plants by introducing TaLsi1 and OsLsi1, its ortholog in rice, into Arabidopsis, a species with a very low innate Si uptake capacity. When expressed constitutively under the control of the CaMV 35S promoter, both TaLsi1 and OsLsi1 were expressed in cells of roots and shoots. Such constitutive expression of TaLsi1 or OsLsi1 resulted in a fourfold to fivefold increase in Si accumulation in transformed plants compared to WT. However, this Si absorption caused deleterious symptoms. When the wheat transporter was expressed under the control of a root-specific promoter (a boron transporter gene (AtNIP5;1) promoter), a similar increase in Si absorption was noted but the plants did not exhibit symptoms and grew normally. These results demonstrate that TaLsi1 is indeed a functional Si transporter as its expression in Arabidopsis leads to increased Si uptake, but that this expression must be confined to root cells for healthy plant development. The availability of this heterologous expression system will facilitate further studies into the mechanisms and benefits of Si uptake.
authors.affiliation: Département de Phytologie, Faculté des Sciences de l'agriculture et de l'alimentation, Centre de Recherche en Horticulture, Université Laval, Pavillon Paul-Comtois, Quebec, QC G1V 0A6, Canada.
authors.forename: Jonatan
authors.initials: J
authors.lastname: Montpetit
authors.forename: Julien
authors.initials: J
authors.lastname: Vivancos
authors.forename: Namiki
authors.initials: N
authors.lastname: Mitani-Ueno
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamaji
authors.forename: Wilfried
authors.initials: W
authors.lastname: Rémus-Borel
authors.forename: François
authors.initials: F
authors.lastname: Belzile
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
authors.forename: Richard R
authors.initials: RR
authors.lastname: Bélanger
mesh_terms: D000042:Absorption / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics; D001483:Base Sequence; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects; D016415:Sequence Alignment; D012825:Silicon / Q000378:metabolism* / Q000494:pharmacology; D014026:Nicotiana / Q000187:drug effects / Q000378:metabolism; D014908:Triticum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; D012825:Silicon