title: Generation of boron-deficiency-tolerant tomato by overexpressing an Arabidopsis thaliana borate transporter AtBOR1.
abstract: Nutrient deficiency in soil poses a widespread agricultural problem. Boron (B) is an essential micronutrient in plants, and its deficiency causes defects in both vegetative and reproductive growth in various crops in the field. In Arabidopsis thaliana, increased expression of a major borate transporter gene AtBOR1 or boric acid channel gene AtNIP5;1 improves plant growth under B-deficient conditions. In this study, we examined whether high expression of a borate transporter gene increases B accumulation in shoots and improves the growth of tomato plant, a model of fruit-bearing crops, under B-deficient conditions. We established three independent transgenic tomato plants lines expressing AtBOR1 using Agrobacterium-mediated transformation of tomato (Solanum lycopersicum L. cv. Micro-Tom). Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that two lines (Line 1 and Line 2) more strongly expressed AtBOR1 than Line 3. Wild-type plants and the transgenic plants were grown hydroponically under B-sufficient and B-deficient conditions. Wild-type and Line 3 (weakly expressing transgenic line) showed a defect in shoot growth under B-deficient conditions, especially in the development of new leaves. However, seedlings of Line 1 and Line 2, the transgenic lines showing strong AtBOR1 expression, did not show the B-deficiency phenotype in newly developing leaves. In agreement with this phenotype, shoot biomass under low-B conditions was higher in the strongly expressing AtBOR1 line. B concentrations in leaves or fruits were also higher in Line 2 and Line 1. The present study demonstrates that strong expression of AtBOR1 improved growth in tomato under B-deficient conditions.
authors.affiliation: Biotechnology Research Center, The University of Tokyo Tokyo, Japan ; Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Uraguchi
authors.affiliation: Biotechnology Research Center, The University of Tokyo Tokyo, Japan ; Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kato
authors.affiliation: Biotechnology Research Center, The University of Tokyo Tokyo, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Hanaoka
authors.affiliation: Biotechnology Research Center, The University of Tokyo Tokyo, Japan ; Creative Research Institution, Hokkaido University, Sapporo Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Miwa
authors.affiliation: Biotechnology Research Center, The University of Tokyo Tokyo, Japan ; Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Fujiwara
keywords: AtBOR1; boron-deficiency; nutrient; tomato; transgenic; transporter
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