Methods and concepts in quantifying resistance to drought, salt and freezing, abiotic stresses that affect plant water status

TLDR

Drought, salinity, and freezing all lower plant cell water availability by reducing water potential, prompting plants to adjust water uptake and loss, accumulate solutes, modify cell walls, and deploy protective proteins to mitigate dehydration and ion imbalance. The study focuses on developing experiments that quantify resistance to realistic, reproducible low water potential, salt, and freezing stresses suitable for high‑throughput genetic analysis. Protocols include polyethylene glycol‑infused agar plates to impose low water potential, root‑elongation assays for salt tolerance, freezing tolerance quantification, and electrolyte‑leakage tests for cellular damage.

Abstract

Summary The abiotic stresses of drought, salinity and freezing are linked by the fact that they all decrease the availability of water to plant cells. This decreased availability of water is quantified as a decrease in water potential. Plants resist low water potential and related stresses by modifying water uptake and loss to avoid low water potential, accumulating solutes and modifying the properties of cell walls to avoid the dehydration induced by low water potential and using protective proteins and mechanisms to tolerate reduced water content by preventing or repairing cell damage. Salt stress also alters plant ion homeostasis, and under many conditions this may be the predominant factor affecting plant performance. Our emphasis is on experiments that quantify resistance to realistic and reproducible low water potential (drought), salt and freezing stresses while being suitable for genetic studies where a large number of lines must be analyzed. Detailed protocols for the use of polyethylene glycol‐infused agar plates to impose low water potential stress, assay of salt tolerance based on root elongation, quantification of freezing tolerance and the use of electrolyte leakage experiments to quantify cellular damage induced by freezing and low water potential are also presented.