title: Two rice plasma membrane intrinsic proteins, OsPIP2;4 and OsPIP2;7, are involved in transport and providing tolerance to boron toxicity.
abstract: Boron (B) toxicity is responsible for low cereal crop production in a number of regions worldwide. In this report, we characterized two rice genes, OsPIP2;4 and OsPIP2;7, for their involvement in B permeability and tolerance. Transcript analysis demonstrated that the expression of OsPIP2;4 and OsPIP2;7 were downregulated in shoots and strongly upregulated in rice roots by high B treatment. Expression of both OsPIP2;4 and OsPIP2;7 in yeast HD9 strain lacking Fps1, ACR3, and Ycf1 resulted in an increased B sensitivity. Furthermore, yeast HD9 strain expressing OsPIP2;4 and OsPIP2;7 accumulated significantly higher B as compared to empty vector control, which suggests their involvement in B transport. Overexpression of OsPIP2;4 and OsPIP2;7 in Arabidopsis imparted higher tolerance under B toxicity. Arabidopsis lines overexpressing OsPIP2;4 and OsPIP2;7 showed significantly higher biomass production and greater root length, however there was no difference in B accumulation in long term uptake assay. Short-term uptake assay using tracer B (¹⁰B) in shoots and roots demonstrated increased ¹⁰B accumulation in Arabidopsis lines expressing OsPIP2;4 and OsPIP2;7, compare to wild type control plants. Efflux assay of B in the roots showed that ¹⁰B was effluxed from the Arabidopsis transgenic plants overexpressing OsPIP2;4 or OsPIP2;7 during the initial 1-h of assay. These data indicate that OsPIP2;4 and OsPIP2;7 are involved in mediating B transport in rice and provide tolerance via efflux of excess B from roots and shoot tissues. These genes will be highly useful in developing B tolerant crops for enhanced yield in the areas affected by high B toxicity.
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA.
authors.forename: Kundan
authors.initials: K
authors.lastname: Kumar
authors.forename: Kareem A
authors.initials: KA
authors.lastname: Mosa
authors.forename: Sudesh
authors.initials: S
authors.lastname: Chhikara
authors.forename: Craig
authors.initials: C
authors.lastname: Musante
authors.forename: Jason C
authors.initials: JC
authors.lastname: White
authors.forename: Om Parkash
authors.initials: OP
authors.lastname: Dhankher
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects; D001895:Boron / Q000493:pharmacokinetics / Q000633:toxicity*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C109281:ACR3 protein, S cerevisiae; D018528:ATP-Binding Cassette Transporters; C093263:FPS1 protein, S cerevisiae; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; C089179:YCF1 protein, S cerevisiae; D001895:Boron