Figure 4.

Ethylene produced by ACC-supplemented seedlings represses hypocotyl elongation of neighboring dark-grown seedlings growing without ACC. Plates with two separate compartments for media but a common airspace were used to grow e- and r-plants in different growth media. Tomato (Solanum lycopersicum) or Arabidopsis thaliana with (+) or without (−) ACC in one compartment as e-plants and different A. thaliana lines without ACC in the other compartment as r-plants. After stratification, plates were incubated in the dark for 4 days. (A) Representative GUS-stained seedlings of the ethylene reporter line EBSn:GUS grown in the r-plant compartment and exposed to volatiles from the indicated e-plants. (B) Barplots representing the mean and SD of hypocotyl length of at least 25 etiolated seedlings of A. thaliana WT and ethylene-insensitive ein2-5 lines grown in the r-plant compartment and exposed to volatiles from the indicated e-plants. Dots represent individual data points. Different letters denote significant differences among means (two-way ANOVA, followed by Tukey test, p-value < 0.05).