Fig. 4.

Effect of growth medium on phenotypic defects in exo70A1 and sec15b mutant plants. (A) Mosaic diagrams displaying incidence of hypocotyl phenotypic classes among 5-day-old exo70A1 and sec15b seedlings grown on different media types (NPA- and auxin-supplemented media with sucrose or mannitol). Column width reflects the number of plants counted; over 300 seedlings were evaluated in each experiment. NM, not malformed. Data from one experiment are shown; similar results were obtained in two independent replicates. Altogether, we found significant effects of medium type on the proportion of phenotypic classes in both mutants (pairwise χ² test with Benjamini–Hochberg correction for multiple testing P<<0.0001; for IAA on exo70A1 mutant P<0.05), except for the effect of IAA in sec15b, which did not significantly differ from the control. No hypocotyl malformations were observed in WT. (B) Boxplots summarizing the hypocotyl length in WT, exo70A1, and sec15b 5 d seedlings depending on cultivation media (over 70 plants per data point evaluated). Within each panel, the letters a, b, c, or d denote groups that did (different letters) or did not (same letters) differ significantly from each other as determined by series of post hoc pairwise Tukey tests with correction for multiple testing (at the level P<0.01—see Methods for statistical methodology). We also noticed significant interaction between genotype and cultivation medium type suggesting that medium composition had different effects on hypocotyl lengths in different genotypes.