Recently, Professor Zhang Lingyun's team published a paper entitled "Na+-preferential ion transporter HKT1; 1 mediates leaf Na+ exclusion and salt tolerance in blueberry" online. This study reported a novel salt-tolerant gene VcHKT1 in blueberry;1 and revealed the important mechanism of promoting salt tolerance by regulating Na+ rejection in leaves.

Soil salinity is a major environmental factor constraining growth and productivity of highbush blueberry (Vaccinium corymbosum). Leaf Na+ content is associated with variation in salt tolerance among blueberry cultivars; however, the determinants and mechanisms conferring leaf Na+ exclusion are unknown. Here, we observed that the blueberry cultivar 'Duke' was more tolerant than 'Sweetheart' and accumulated less Na+ in leaves under salt stress conditions. Through transcript profiling, we identified a member of the high-affinity K+ transporter (HKT) family in blueberry, VcHKT1;1, as a candidate gene involved in leaf Na+ exclusion and salt tolerance. VcHKT1;1 encodes a Na+-preferential transporter localized to the plasma membrane and is preferentially expressed in the root stele. Heterologous expression of VcHKT1;1 in Arabidopsis (Arabidopsis thaliana) rescued the salt hypersensitivity phenotype of the athkt1 mutant. Decreased VcHKT1;1 transcript levels in blueberry plants expressing antisense-VcHKT1;1 led to increased Na+ concentrations in xylem sap and higher leaf Na+ contents compared with wild-type plants, indicating that VcHKT1;1 promotes leaf Na+ exclusion by retrieving Na+ from xylem sap. A naturally occurring 8-bp insertion in the promoter increased the transcription level of VcHKT1;1, thus promoting leaf Na+ exclusion and blueberry salt tolerance. Collectively, we provide evidence that VcHKT1;1 promotes leaf Na+ exclusion and propose natural variation in VcHKT1;1 will be valuable for breeding Na+-tolerant blueberry cultivars in the future.

Professor Zhang Lingyun and Associate Professor Cao Yibo from the College of Forestry of Beijing Forestry University are the corresponding authors of the paper. Song Huifang, PhD candidate and Associate Professor Cao Yibo are the co-first authors of the paper.

This work was supported by the National Natural Science Foundation of China (grant no. 32101555 to Y.C. and grant no. 31872942 to L.Z.) and the China Postdoctoral Science Foundation (grant no. 2021T140060 and grant no. 2020M680403 to Y.C.).

Paper link: https://doi.org/10.1093/plphys/kiad510