title: Boron toxicity tolerance in barley through reduced expression of the multifunctional aquaporin HvNIP2;1.
abstract: Boron (B) toxicity is a significant limitation to cereal crop production in a number of regions worldwide. Here we describe the cloning of a gene from barley (Hordeum vulgare), underlying the chromosome 6H B toxicity tolerance quantitative trait locus. It is the second B toxicity tolerance gene identified in barley. Previously, we identified the gene Bot1 that functions as an efflux transporter in B toxicity-tolerant barley to move B out of the plant. The gene identified in this work encodes HvNIP2;1, an aquaporin from the nodulin-26-like intrinsic protein (NIP) subfamily that was recently described as a silicon influx transporter in barley and rice (Oryza sativa). Here we show that a rice mutant for this gene also shows reduced B accumulation in leaf blades compared to wild type and that the mutant protein alters growth of yeast (Saccharomyces cerevisiae) under high B. HvNIP2;1 facilitates significant transport of B when expressed in Xenopus oocytes compared to controls and to another NIP (NOD26), and also in yeast plasma membranes that appear to have relatively high B permeability. We propose that tolerance to high soil B is mediated by reduced expression of HvNIP2;1 to limit B uptake, as well as by increased expression of Bot1 to remove B from roots and sensitive tissues. Together with Bot1, the multifunctional aquaporin HvNIP2;1 is an important determinant of B toxicity tolerance in barley.
authors.affiliation: Australian Centre for Plant Functional Genomics , University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schnurbusch
authors.forename: Julie
authors.initials: J
authors.lastname: Hayes
authors.forename: Maria
authors.initials: M
authors.lastname: Hrmova
authors.forename: Ute
authors.initials: U
authors.lastname: Baumann
authors.forename: Sunita A
authors.initials: SA
authors.lastname: Ramesh
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Tyerman
authors.forename: Peter
authors.initials: P
authors.lastname: Langridge
authors.forename: Tim
authors.initials: T
authors.lastname: Sutton
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001895:Boron / Q000633:toxicity*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D040641:Quantitative Trait Loci; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D014981:Xenopus
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D001895:Boron