OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice

Natsuko I. Kobayashi, Naoki Yamaji, Hiroki Yamamoto, Kaoru Okubo, Hiroki Ueno, Alex Costa, Keitaro Tanoi, Hideo Matsumura, Miho Fujii-Kashino, Tomoki Horiuchi, Mohammad Al Nayef, Sergey Shabala, Gynheung An, Jian Feng Ma, Tomoaki Horie

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+/Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+-selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent T-DNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.

Original languageEnglish
JournalPlant Journal
DOIs
Publication statusAccepted/In press - 2017

Fingerprint

leaf blade
Salts
toxicity
salts
salt stress
Phloem
Xylem
rice
mutants
phloem
xylem
tracer techniques
Salt-Tolerance
leaves
shoots
Quantitative Trait Loci
vascular bundles
gene targeting
salt tolerance
Genes

Keywords

  • HKT
  • Na exclusion
  • Oryza sativa
  • Phloem
  • Salt tolerance
  • Xylem

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

Cite this

OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice. / Kobayashi, Natsuko I.; Yamaji, Naoki; Yamamoto, Hiroki; Okubo, Kaoru; Ueno, Hiroki; Costa, Alex; Tanoi, Keitaro; Matsumura, Hideo; Fujii-Kashino, Miho; Horiuchi, Tomoki; Nayef, Mohammad Al; Shabala, Sergey; An, Gynheung; Ma, Jian Feng; Horie, Tomoaki.

In: Plant Journal, 2017.

Research output: Contribution to journalArticle

Kobayashi, NI, Yamaji, N, Yamamoto, H, Okubo, K, Ueno, H, Costa, A, Tanoi, K, Matsumura, H, Fujii-Kashino, M, Horiuchi, T, Nayef, MA, Shabala, S, An, G, Ma, JF & Horie, T 2017, 'OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice', Plant Journal. https://doi.org/10.1111/tpj.13595
Kobayashi, Natsuko I. ; Yamaji, Naoki ; Yamamoto, Hiroki ; Okubo, Kaoru ; Ueno, Hiroki ; Costa, Alex ; Tanoi, Keitaro ; Matsumura, Hideo ; Fujii-Kashino, Miho ; Horiuchi, Tomoki ; Nayef, Mohammad Al ; Shabala, Sergey ; An, Gynheung ; Ma, Jian Feng ; Horie, Tomoaki. / OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice. In: Plant Journal. 2017.
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abstract = "Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+/Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+-selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent T-DNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.",
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AU - Kobayashi, Natsuko I.

AU - Yamaji, Naoki

AU - Yamamoto, Hiroki

AU - Okubo, Kaoru

AU - Ueno, Hiroki

AU - Costa, Alex

AU - Tanoi, Keitaro

AU - Matsumura, Hideo

AU - Fujii-Kashino, Miho

AU - Horiuchi, Tomoki

AU - Nayef, Mohammad Al

AU - Shabala, Sergey

AU - An, Gynheung

AU - Ma, Jian Feng

AU - Horie, Tomoaki

PY - 2017

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AB - Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+/Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+-selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent T-DNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.

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