Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance

Paul, Newton Chandra; Imran, Shahin; Mitsumoto, Anri; Mori, Izumi C.; Katsuhara, Maki

doi:10.3390/cells14171305

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Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance

by

Newton Chandra Paul

^1,2

,

Shahin Imran

^1,2

,

Anri Mitsumoto

¹,

Izumi C. Mori

¹

and

Maki Katsuhara

^1,*

¹

Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan

²

Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh

^*

Author to whom correspondence should be addressed.

Cells 2025, 14(17), 1305; https://doi.org/10.3390/cells14171305

Submission received: 29 July 2025 / Revised: 11 August 2025 / Accepted: 19 August 2025 / Published: 22 August 2025

(This article belongs to the Special Issue Membrane Dynamics and the Role of Aquaporins in Plant Cells)

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Abstract

Aquaporins (AQPs) are membrane proteins that facilitate the transport of water and solutes. Among AQPs, plasma membrane intrinsic proteins (PIPs) play a critical role in maintaining water balance between the internal and external cell environments. This study focuses on the tomato due to its economic importance and cultivation under moderate salinity conditions in Japan. A swelling assay using X. laevis oocyte confirmed that all five examined tomato SlPIP2 isoforms showed water transport activity. Among them, two-electrode voltage clamp (TEVC) experiments showed that only SlPIP2;1, SlPIP2;4, and SlPIP2;8 transport Na⁺ and K⁺, with no transport activity for Cs⁺, Rb⁺, Li⁺, or Cl⁻. CaCl₂ (1.8 mM) reduced ionic currents by approximately 45% compared to 30 µM free-Ca²⁺. These isoforms function as very low-affinity Na⁺ and K⁺ transporters. Expression analysis showed that SlPIP2;4 and SlPIP2;8 had low, stable expression, while SlPIP2;1 was strongly upregulated in roots NaCl treatment (200 mM, 17days), suggesting distinct physiological roles for these ion-conducting AQPs (icAQPs). These data hypothesized that tomato icAQPs play a critical role in ion homeostasis, particularly under salinity stress. In conclusion, the first icAQPs have been identified in the dicotyledonous crop. These icAQPs are essential for plant resilience under salt stress.

Keywords: Aquaporin (AQP); ion transport; plasma membrane intrinsic proteins (PIPs); tomato; oocytes; water transport

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MDPI and ACS Style

Paul, N.C.; Imran, S.; Mitsumoto, A.; Mori, I.C.; Katsuhara, M. Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance. Cells 2025, 14, 1305. https://doi.org/10.3390/cells14171305

AMA Style

Paul NC, Imran S, Mitsumoto A, Mori IC, Katsuhara M. Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance. Cells. 2025; 14(17):1305. https://doi.org/10.3390/cells14171305

Chicago/Turabian Style

Paul, Newton Chandra, Shahin Imran, Anri Mitsumoto, Izumi C. Mori, and Maki Katsuhara. 2025. "Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance" Cells 14, no. 17: 1305. https://doi.org/10.3390/cells14171305

APA Style

Paul, N. C., Imran, S., Mitsumoto, A., Mori, I. C., & Katsuhara, M. (2025). Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance. Cells, 14(17), 1305. https://doi.org/10.3390/cells14171305

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance

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