title: Highly boron deficiency-tolerant plants generated by enhanced expression of NIP5;1, a boric acid channel.
abstract: Boron (B) is an essential element for plants, and B deficiency is a worldwide agricultural problem. In B-deficient areas, B is often supplied as fertilizer, but excess B can be toxic to both plants and animals. Generation of B deficiency-tolerant plants could reduce B fertilizer use. Improved fertility under B-limiting conditions in Arabidopsis thaliana by overexpression of BOR1, a B transporter, has been reported, but the root growth was not improved by the BOR1 overexpression. In this study, we report that enhanced expression of NIP5;1, a boric acid channel for efficient B uptake, resulted in improved root elongation under B-limiting conditions in A. thaliana. An NIP5;1 activation tag line, which has a T-DNA insertion with enhancer sequences near the NIP5;1 gene, showed improved root elongation under B limitation. We generated a construct which mimics the tag line: the cauliflower mosaic virus 35S RNA promoter was inserted at 1,357 bp upstream of the NIP5;1 transcription initiation site. Introduction of this construct into the nip5;1-1 mutant and the BOR1 overexpresser resulted in enhanced expression of NIP5;1 and improved root elongation under low B supply. Furthermore, one of the transgenic lines exhibited improved fertility and short-term B uptake. Our results demonstrate successful improvement of B deficiency tolerance and the potential of enhancing expression of a mineral nutrient channel gene to improve growth under nutrient-limiting conditions.
authors.affiliation: Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kato
authors.forename: Kyoko
authors.initials: K
authors.lastname: Miwa
authors.forename: Junpei
authors.initials: J
authors.lastname: Takano
authors.forename: Motoko
authors.initials: M
authors.lastname: Wada
authors.forename: Toru
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001888:Boric Acids / Q000378:metabolism*; D001895:Boron / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004742:Enhancer Elements, Genetic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D016254:Mutagenesis, Insertional; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D001888:Boric Acids; D004269:DNA, Bacterial; C512214:NIP5;1 protein, Arabidopsis; C036483:T-DNA; D001895:Boron; C032688:boric acid