Proline: A Reliable Biochemical Marker of Plant Abiotic Stress Tolerance?
Abstract
Climate change is placing global agriculture under growing pressure, as plants must withstand extreme environmental conditions such as drought and high salinity, both inducing osmotic and oxidative stress. As part of their survival strategies, plants accumulate protective molecules (osmolytes), including the amino acid proline. For decades, plant biology has largely assumed that high proline accumulation under stress signals strong stress tolerance. However, this review challenges that "proline-centric" perspective. Analyses across a wide range of plant species reveal a more complex picture. Stress-induced proline accumulation is not universal: in some species, proline levels remain relatively unchanged, with other metabolites acting as functional osmolytes, or increase only in response to artificially applied severe stress conditions. Even when proline increases, its absolute concentrations may be too low to contribute significantly to osmotic adjustment. Nevertheless, proline may still be involved in stress tolerance mechanisms through its additional roles, detoxifying reactive oxygen species (ROS), directly stabilising proteins or acting as a stress signalling molecule. Comparative analyses of genetically related taxa with varying degrees of stress tolerance sometimes show negative correlations between proline accumulation and tolerance, with higher proline concentrations measured in the most sensitive genotypes. Overall, the evidence indicates that proline's role in plant survival is highly context-dependent and strongly influenced by genetic background and must therefore be evaluated on a case-by-case basis. Distinguishing whether proline acts as an adaptive defence or merely as a biochemical marker of physiological strain under stress is essential for accurately assessing plant stress tolerance.
Related
- Abiotic stress sensing in plants: Biochemical and biophysical basis
- Biostimulants for sustainable agriculture: enhancing plant tolerance to abiotic and biotic stresses
- Nanotechnology-Enabled Strategies for Enhancing Plant Abiotic Stress Tolerance
- Molecular Mechanisms of Plant Abiotic Stress Tolerance: 2nd Edition
- Polycistronic amiRNA‐Mediated Multiplex Silencing of Clade A PP2Cs Confers Broad‐Spectrum Abiotic Stress Tolerance in Wheat
BibTeX
@article{luca2026proline,
title = {{Proline: A Reliable Biochemical Marker of Plant Abiotic Stress Tolerance?}},
author = {Delia Maria Luca and Marius-Nicușor Grigore and Oscar Vicente},
journal = {Plants},
year = {2026},
month = aug,
doi = {10.3390/plants15162478},
url = {https://doi.org/10.3390/plants15162478},
note = {CC BY},
}
RIS
TY - JOUR
TI - Proline: A Reliable Biochemical Marker of Plant Abiotic Stress Tolerance?
AU - Delia Maria Luca
AU - Marius-Nicușor Grigore
AU - Oscar Vicente
PY - 2026
DA - 2026/08/15
JO - Plants
DO - 10.3390/plants15162478
UR - https://doi.org/10.3390/plants15162478
AB - Climate change is placing global agriculture under growing pressure, as plants must withstand extreme environmental conditions such as drought and high salinity, both inducing osmotic and oxidative stress. As part of their survival strategies, plants accumulate protective molecules (osmolytes), including the amino acid proline. For decades, plant biology has largely assumed that high proline accumulation under stress signals strong stress tolerance. However, this review challenges that "proline-centric" perspective. Analyses across a wide range of plant species reveal a more complex picture. Stress-induced proline accumulation is not universal: in some species, proline levels remain relatively unchanged, with other metabolites acting as functional osmolytes, or increase only in response to artificially applied severe stress conditions. Even when proline increases, its absolute concentrations may be too low to contribute significantly to osmotic adjustment. Nevertheless, proline may still be involved in stress tolerance mechanisms through its additional roles, detoxifying reactive oxygen species (ROS), directly stabilising proteins or acting as a stress signalling molecule. Comparative analyses of genetically related taxa with varying degrees of stress tolerance sometimes show negative correlations between proline accumulation and tolerance, with higher proline concentrations measured in the most sensitive genotypes. Overall, the evidence indicates that proline's role in plant survival is highly context-dependent and strongly influenced by genetic background and must therefore be evaluated on a case-by-case basis. Distinguishing whether proline acts as an adaptive defence or merely as a biochemical marker of physiological strain under stress is essential for accurately assessing plant stress tolerance.
SN - 2223-7747
ER -