CmCNIH1 improves salt tolerance by influencing the trafficking of CmHKT1;1 in pumpkin

• Published in: The Plant journal : for cell and molecular biology 2023-06, Vol.114 (6), p.1353-1368
• Main Authors: Wei, Lanxing, Liu, Liu, Chen, Zhi, Huang, Yuan, Yang, Li, Wang, Pengwei, Xue, Shaowu, Bie, Zhilong
• Format: Article
• Language: English
• Subjects: Abiotic stress; Cargo; CmCNIH1; CmHKT1; 1; CRISPR/Cas9; Cucurbita - metabolism; Endoplasmic reticulum; Gametocytes; Gene Expression Regulation, Plant; Golgi apparatus; Homeostasis; Localization; Membrane Transport Proteins - metabolism; Mutants; Oocytes; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - metabolism; pumpkin; Pumpkins; Receptors; Regulatory mechanisms (biology); Rootstocks; Saccharomyces cerevisiae - metabolism; salinity stress; Salinity tolerance; Salt; Salt Tolerance; Sodium; Soil resistance; Tobacco; Yeast; Yeasts
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.16197

SUMMARY Pumpkin is often used as a rootstock for other Cucurbitaceae crops due to its resistance to soil‐borne diseases and abiotic stress. Pumpkin rootstocks use a sodium transporter (CmHKT1;1) to promote the transport of Na+ from the shoot to the root effectively and improve the salt tolerance of the scion. However, the molecular regulatory mechanisms that influence the activity of CmHKT1;1 during salt stress response remain unknown. In this study, CmCNIH1, a cornichon homolog, was identified as a potential cargo receptor for CmHKT1;1. Yeast two‐hybrid, biomolecular fluorescence complementation and luciferase complementary assays demonstrated that CmCNIH1 and CmHKT1;1 could interact. CmCNIH1 was a key component of the cellular vesicle transport machinery located in the endoplasmic reticulum (ER), ER export site and Golgi apparatus. A CmCNIH1 knockout mutant was more sensitive to salt stress than the wild‐type (WT). In addition, ion homeostasis was disrupted in cmcnih1 mutants, which had higher Na+ and lower K+ content in shoots and roots than the WT. Two‐electrode voltage‐clamp experiment displayed that CmCNIH1 could not influence the Na+ current that passed through the plasma membrane (PM) in CmHKT1;1‐expressing Xenopus laevis oocytes. Data from co‐localization assays indicated that intact CmCNIH1 protein could alter the subcellular localization of CmHKT1;1 in tobacco leaf, pumpkin root and yeast. In summary, CmCNIH1 may function as a cargo receptor that regulates the localization of CmHKT1;1 to the PM to improve salt tolerance in pumpkin. Significance Statement In this study, we identified a CmHKT1;1 interacting protein, named CmCNIH1, which conferred salt tolerance by mediating the trafficking of CmHKT1;1.