ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Abiotic Stress
Identification, Classification, and Stress-responsive Regulation of HAK Family 1 Genes in Poplar 2
Provisionally accepted
- College of Forestry, Southwest Forestry University, Kunming, China
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Potassium (K+) is essential for plant growth and high-affinity K+ transporters (HAKs) play 12 vital roles in K+ uptake, translocation, and stress response. Although HAK genes have been 13 characterized in various plants, they remain unexplored in Populus yunnanensis, an ecologically 14 and economically important tree species in Southwest China. Here, we identified 32 HAKs in P. 15 yunnanensis and classified them into six distinct phylogenetic groups, a structure conserved across 16 six analyzed Populus species. Evolutionary analysis suggested that purifying selection (Ka/Ks < 1) 17 has shaped all HAKs of thesix tested poplar species. with gene duplication events contributing to 18 its expansion. All PyHAKs that were conserved contained abundant helical structures and 19 transmembrane segments, which supported their conserved transport function. However, 20 variations in protein and gene structure suggest potential functional diversification. Promoter 21 analysis revealed an abundance of hormone-responsive cis-elements, and expression profiling 22 confirmed that selected PyHAKs respond significantly to ABA, drought, heat, and osmotic stress. 23 Furthermore, protein-protein interaction predictions, which were partially validated by yeast 24 two-hybrid assays, indicated that PyHAK activity may be posttranslationally regulated via 25 phosphorylation by calcineurin B-like (CBL) proteins. Our study provides the first 26 comprehensive genomic and functional analysis of the HAK family in P. yunnanensis, establishing 27 a foundation for future research on potassium regulation and stress resistance in woody plants.
Keywords: HAK, poplar, K+ transport, stress response, Phosphorylation
Received: 22 Aug 2025; Accepted: 24 Oct 2025.
Copyright: © 2025 Liu, Shi, Chen, Wang, Liu and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Aizhong Liu, liuaizhong@mail.kib.ac.cn
Ping Li, liping2020@swfu.edu.cn
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