Phenotypic Analysis of <i>Arabidopsis</i> Mutants: Electrolyte Leakage after Freezing Stress

INTRODUCTION Abiotic stress such as high salt or low temperature adversely affects plant growth and development. Salt stress inhibits seed germination, retards plant growth, and accelerates senescence. Freezing or drought stress can cause cell damage and plant death. The following parameters can be used to evaluate plant tolerance to salt, drought, or freezing stress: root elongation, fresh weight gain, seed germination, electrolyte leakage (described here), or water-loss measurement. Several stress mutants have been characterized using these tests, including hos1 and hos2 , which show higher expression of some stress-regulated genes when exposed to low-temperature stress; hos5 , which shows higher expression of some stress-regulated genes under abscisic acid (ABA) and salt treatments; sfr mutants, which are deficient in freezing tolerance; and eskimo1 , which is constitutively freezing tolerant. This protocol describes an electrolyte leakage assay that can be used to measure the degree of cell damage after freezing stress in Arabidopsis . The levels of stress suggested in this protocol may need to be adjusted, depending on the ecotype and growth conditions used.