Function and Regulatory Mechanism of Hvspx4 in Maintaining Phosphate Homeostasis in Barley
Document Type
Article
Subject Area(s)
Hordeum (genetics, metabolism, growth & development); Phosphates (metabolism); Homeostasis; Plant Proteins (metabolism, genetics); Gene Expression Regulation, Plant; Transcription Factors (metabolism, genetics); Plants, Genetically Modified; Phosphorus (metabolism); Promoter Regions, Genetic
Abstract
Low-phosphorus (LP) tolerance varies among plant species and genotypes within a species, and the molecular mechanisms underlying phosphorus (P) signaling in barley (Hordeum vulgare L.) remain unclear. Here, we report the function of HvSPX4, a member of the SPX (SYG1/Pho81/XPR1) subfamily, in maintaining P homeostasis and regulating LP responses in barley. HvSPX4 exhibited lower expression in the LP-tolerant genotype Zaoaibai than the LP-sensitive Salooni2. Knocking out HvSPX4 resulted in growth inhibition due to over-accumulation of P under normal P conditions. Overexpression of HvSPX4 resulted in reduced biomass under both normal and LP conditions and less P uptake, especially in shoots under normal P conditions. HvSPX4 directly interacted with transcription factors Phosphate Starvation Response 1/2/4 (HvPHR1/2/4) to inactivate PSI genes such as Phosphate Transporter 1;6 (HvPHT1;6). An expression genome-wide association studies analysis of HvSPX4 expression revealed that a 50-bp insertion in the promoter region of HvSPX4 enhances its expression, probably due to the presence of 2 CAAT boxes in this insertion. Moreover, the absence of the insertion was associated with improved plant growth in a natural population of barley under LP conditions. These findings suggest that fine-tuning the expression of HvSPX4 could be a promising strategy to improve plant adaptation to LP stress.
Digital Object Identifier (DOI)
Publication Info
Published in Plant Physiology, Volume 199, Issue 1, 2025.
APA Citation
Zhang, J., Zhou, Y., Zhang, Y., Zhao, H., Liang, Q., Xu, Y., Gu, Z., Huang, T., Tu, Y., Ye, L., Shen, Q., Wu, D., Zhang, G., & Cai, S. (2025). Function and regulatory mechanism of HvSPX4 in maintaining phosphate homeostasis in barley. Plant Physiology, 199(1).https://doi.org/10.1093/plphys/kiaf390
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