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<p>Phosphate (Pi) is an essential macronutrient, and plants have evolved diverse transporter families to maintain Pi acquisition, remobilization, and homeostasis under fluctuating environmental conditions. In this study, we performed a comprehensive genome-wide characterization of the phosphate transporter (PHT) gene family in wheat (<i>Triticum aestivum</i> L.), integrating comparative phylogenomics, structural, regulatory, functional, and expression analyses. Phylogenetic reconstruction with barley, rice, maize, sorghum, and Arabidopsis resolved the PHT family into four major clades, revealing a large monocot-specific expansion in PHT1 transporters and a dicot-specific retention of intracellular subfamilies. Gene structure and MEME motif analysis confirmed a conserved 12-transmembrane Major Facilitator Superfamily (MFS) backbone with limited clade-specific variation, while promoter analysis uncovered a rich cis-regulatory landscape integrating Pi status with light, hormone, and abiotic stress cues. Subcellular localization predictions indicated that most TaPHTs are plasma membrane transporters, with a minority showing vacuolar, ER, Golgi, or chloroplast signals, pointing to functional diversification. Gene Ontology enrichment further supported roles in active transmembrane phosphate transport. Protein–protein interaction networks revealed a centralized regulatory hub linking multiple TaPHT paralogs to shared trafficking and regulatory partners. Expression profiling across abiotic, biotic, and nutrient treatments separated <i>TaPHTs</i> into two functional modules, including nutrient-responsive transporters (<i>TaPHT1/2</i>) induced under phosphate supply, and biotic and water-status–responsive transporters (<i>TaPHT3/11</i>) induced under Fusarium infection and re-watering. Our time-course qRT-PCR analysis showed that drought and salinity trigger distinct, gene-specific expression profiles within the PHT family, with salinity provoking the stronger and more sustained induction. The relative gene expression of <i>TaPHT1</i> and <i>TaPHT11</i> emerged as the main stress-responsive transporters, displaying rapid, robust, and persistent upregulation, whereas the expression of <i>TaPHT3</i> gene showed a moderate, salt-biased response, and <i>TaPHT2</i> only weak, transient changes. These findings provided new insight into how phosphate transport is differentially recruited during early wheat responses to drought and salinity and identified the genes <i>TaPHT1</i> and <i>TaPHT11</i> as key candidates for improving nutrient use efficiency and abiotic stress tolerance. Together, these results highlight that wheat PHTs combine conserved structural features with lineage-specific expansions and specialized regulatory programs, supporting a dual role in basal Pi homeostasis and adaptive stress responses. This integrative framework provides a foundation for functional prioritization of <i>TaPHT</i> genes in molecular breeding and biotechnological strategies aimed at improving phosphate-use efficiency and stress resilience in cereals.</p>

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Genome-wide identification, phylogeny, and differential expression of wheat phosphate transporters under drought and salinity stress conditions

  • 期刊论文

  • 发表日期：

    2026年2月7日

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  • Khairiah Mubarak Alwutayd,
  • Ashwag Shami,
  • Ahmad M. Alqudah,
  • Samar G. Thabet

摘要

Phosphate (Pi) is an essential macronutrient, and plants have evolved diverse transporter families to maintain Pi acquisition, remobilization, and homeostasis under fluctuating environmental conditions. In this study, we performed a comprehensive genome-wide characterization of the phosphate transporter (PHT) gene family in wheat (Triticum aestivum L.), integrating comparative phylogenomics, structural, regulatory, functional, and expression analyses. Phylogenetic reconstruction with barley, rice, maize, sorghum, and Arabidopsis resolved the PHT family into four major clades, revealing a large monocot-specific expansion in PHT1 transporters and a dicot-specific retention of intracellular subfamilies. Gene structure and MEME motif analysis confirmed a conserved 12-transmembrane Major Facilitator Superfamily (MFS) backbone with limited clade-specific variation, while promoter analysis uncovered a rich cis-regulatory landscape integrating Pi status with light, hormone, and abiotic stress cues. Subcellular localization predictions indicated that most TaPHTs are plasma membrane transporters, with a minority showing vacuolar, ER, Golgi, or chloroplast signals, pointing to functional diversification. Gene Ontology enrichment further supported roles in active transmembrane phosphate transport. Protein–protein interaction networks revealed a centralized regulatory hub linking multiple TaPHT paralogs to shared trafficking and regulatory partners. Expression profiling across abiotic, biotic, and nutrient treatments separated TaPHTs into two functional modules, including nutrient-responsive transporters (TaPHT1/2) induced under phosphate supply, and biotic and water-status–responsive transporters (TaPHT3/11) induced under Fusarium infection and re-watering. Our time-course qRT-PCR analysis showed that drought and salinity trigger distinct, gene-specific expression profiles within the PHT family, with salinity provoking the stronger and more sustained induction. The relative gene expression of TaPHT1 and TaPHT11 emerged as the main stress-responsive transporters, displaying rapid, robust, and persistent upregulation, whereas the expression of TaPHT3 gene showed a moderate, salt-biased response, and TaPHT2 only weak, transient changes. These findings provided new insight into how phosphate transport is differentially recruited during early wheat responses to drought and salinity and identified the genes TaPHT1 and TaPHT11 as key candidates for improving nutrient use efficiency and abiotic stress tolerance. Together, these results highlight that wheat PHTs combine conserved structural features with lineage-specific expansions and specialized regulatory programs, supporting a dual role in basal Pi homeostasis and adaptive stress responses. This integrative framework provides a foundation for functional prioritization of TaPHT genes in molecular breeding and biotechnological strategies aimed at improving phosphate-use efficiency and stress resilience in cereals.