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Perspectives on Deciphering Thermotolerance Mechanisms in Heliotropium thermophilum: Integrating Biochemical Responses and Gene Expression Patterns

Asiye SEZGİN MUSLU , Necdet Mehmet Ünel, Aykut Saglam , Mehmet Cengiz Baloglu, Asim KADIOĞLU

Abstract

High temperature stress significantly impacts plant viability and productivity. Understanding thermotolerance mechanisms is essential for developing resilient crops. Heliotropium thermophilum, endemic to geothermal areas with extreme soil temperatures, serves as a model for studying plant high temperature stress responses. This study aims to elucidate the biochemical and molecular mechanisms underlying thermotolerance in H. thermophilum. Biochemical assays quantified osmoprotectants (proline, soluble sugars, glycine-betaine, and total phenolics) and lipid peroxidation in H. thermophilum under different soil temperatures. Transcriptome analysis and quantitative Real-Time PCR were performed to validate the expression of genes involved in osmoprotectant biosynthesis, antioxidant defense, and cell wall modification. Glycine-betaine and proline levels increased by up to 189% and 104%, respectively, during peak stress. Elevated total phenolics correlated with reduced lipid peroxidation, indicating effective oxidative stress mitigation. Transcriptome analysis revealed significant upregulation of genes related to osmoprotectant biosynthesis, antioxidant defense, and cell wall modification, with notable expression of heat shock proteins and sugar transport genes. H. thermophilum employs an integrative biochemical and molecular strategy to withstand high soil temperatures, involving osmoprotectant accumulation, enhanced antioxidant defenses, and dynamic cell wall remodeling. These findings provide insights into thermotolerance mechanisms, offering potential targets for enhancing high temperature stress resilience in other crops. This study contributes to understanding plant-soil interactions and developing strategies to ensure agricultural productivity amid global climate change. Keywords: Heliotropium thermophilum, high soil temperature, thermotolerance, osmoprotectants, transcriptome analysis, quantitative Real-Time PCR, cell wall modification, antioxidant defense

FP24288  Accepted 18 August 2025

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