Figure 7.

Ethylene-DELLA interactions during hypocotyl elongation. A to D, The pRGA∷GFP:RGA reporter shows the abundance of the DELLA protein RGA (green speckles on a background of red-fluorescing chloroplasts). Note that RGA abundance is enhanced by the ethylene precursor ACC under low blue light conditions. E and F, ACC dose-response curves in wild-type Ler (E) and the quadruple DELLA knockout mutant (F) under normal and low blue light conditions. G, ACC-induced stimulation of hypocotyl length does not depend on GA, as evidenced by the GA-deficient ga1-3 and the GA-insensitive gai (DELLA gain-of-function) mutants. Data are means ± se (n = 30–50). Different letters indicate significant differences.