Fig. 2
From: Q&A: How do plants respond to ethylene and what is its importance?
The triple response assay in Arabidopsis: a rapid method for screening for ethylene-response mutants. Dark-grown wild-type seedlings germinated on agar medium in the presence of exogenous ethylene display the triple response phenotype: a short and thick hypocotyl, an exaggerated apical hook (labeled in the figure) and a short root (not visible in this image). The single tall seedling (approximately 1Â cm in length) is an ethylene-insensitive mutant with a long and thin hypocotyl (labeled in the figure) and no apical hook. From the cover of Science volume 241 (August 26, 1988); photograph by Kurt Stepnitz (Michigan State University). Reprinted with permission of AAAS