Drought survival analysis of alx8 and ost1-2 plants. (a, b) Application of the threshold test. The Fv/Fm measurements of individual (a) Columbia (◇) and alx8 (Δ), and (b) Landsberg (□) and ost1-2 (○) specimens are shown. Filled symbols represent controls; empty symbols represent plants that failed to evidence signs of recovery within 3 days of rehydration. The 33% threshold for a typical average control Fv/Fm of 0.800 is shown as a dotted line. For control populations, n = 4 for each line; for drought-treated populations, n = 15 for Columbia, Landsberg and ost1-2, and n = 8 for alx8. (c) Comparison of drought survival times of alx8, ost1-2 and wild-type plants. Error bars indicate standard deviation. Pairwise t-tests were performed for the mutant lines against survival times of their corresponding wild-type (Columbia for alx8, Landsberg for ost1-2), yielding p-values as shown.