EXPRESSION OF PLASTIDIAL AND MITOCHONDRIAL SHSP GENES IN NICOTIANA SYLVESTRIS UNDER HEAT STRESS
DOI:
https://doi.org/10.31861/biosystems2026.01.073Keywords:
abiotic stress, bioinformatic analysis, genetic polymorphism, gene expression, multigene family, heat stress, sHSP, Nicotiana sylvestrisAbstract
Understanding the mechanisms that protect plants against elevated temperatures has become partic-ularly important under climate change. Small heat shock proteins (sHSPs) play a key role in main-taining protein homeostasis and regulating plant responses to stress factors, particularly heat stress. In this study, a bioinformatic and experimental analysis of the sHsp gene family in Nicotiana syl-vestris was performed. The use of an updated annotated genome assembly enabled the identification of 48 sHsp genes, representing a substantial expansion compared with previous reports. These genes were assigned to 16 structural classes, including proteins with different predicted subcellular locali-zations.
For further analysis, six genes encoding sHSPs localized to plastids and mitochondria were selected: NslHsp18.1-MPI, NslHsp21.3-MPI, NslHsp24.4-MPI, NslHsp24.9-PI, NslHsp26.4-PI, and NslHsp25.7-MPII. The expression profiles of these genes were assessed by quantitative RT-PCR in leaves of N. sylvestris under control conditions (25°C) and after short-term heat shock treatments at 37°C and 42°C. At the physiologically optimal temperature, the expression levels of the investigated sHsp genes were low or undetectable. Incubation at 37°C resulted in a marked induction of expres-sion of NslHsp24.4-MPI, NslHsp24.9-PI, NslHsp26.4-PI, and NslHsp25.7-MPII, and this effect became even more pronounced at 42°C. In contrast, two genes, NslHsp18.1-MPI and NslHsp21.3-MPI, remained only moderately expressed even under more severe heat stress conditions, which may reflect their auxiliary role in the stress response.
These findings demonstrate the class- and compartment-specific patterns of sHSP induction in N. sylvestris and expand our understanding of the molecular basis of thermotolerance in members of the genus Nicotiana.
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