Paul Newton Chandra, Imran Shahin, Mitsumoto Anri, Mori Izumi C, Katsuhara Maki
Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan.
Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh.
Cells. 2025 Aug 22;14(17):1305. doi: 10.3390/cells14171305.
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 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. CaCl (1.8 mM) reduced ionic currents by approximately 45% compared to 30 µM free-Ca. These isoforms function as very low-affinity Na and K transporters. Expression analysis showed that and had low, stable expression, while 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.
水通道蛋白（AQPs）是促进水和溶质运输的膜蛋白。在水通道蛋白中，质膜内在蛋白（PIPs）在维持细胞内外环境的水平衡中起着关键作用。由于番茄具有经济重要性且在日本中等盐度条件下种植，本研究聚焦于番茄。使用卵母细胞进行的肿胀试验证实，所检测的所有五种番茄SlPIP2亚型均表现出水运输活性。其中，双电极电压钳（TEVC）实验表明，只有SlPIP2;1、SlPIP2;4和SlPIP2;8能转运Na和K，对Cs、Rb、Li或Cl没有转运活性。与30μM游离Ca相比，CaCl（1.8 mM）使离子电流降低了约45%。这些亚型作为极低亲和力的Na和K转运体发挥作用。表达分析表明，[此处原文缺失具体基因名称]表达量低且稳定，而[此处原文缺失具体基因名称]在根NaCl处理（200 mM，17天）中强烈上调，表明这些离子传导水通道蛋白（icAQPs）具有不同的生理作用。这些数据推测番茄icAQPs在离子稳态中起关键作用，尤其是在盐胁迫下。总之，首次在双子叶作物中鉴定出icAQPs。这些icAQPs对植物在盐胁迫下的恢复力至关重要。
