Fig. 1.

Persistent shade avoidance in the absence of elevated auxin levels in Arabidopsis. Shade intensity (based on the inverse of photosensory receptor activity estimated from the light spectra) is 0 for simulated sunlight, 0.07 for weak shade, and 0.09 for deep shade. (A) Columbia wild-type and sav3 hypocotyl growth rate during day 4 (0 h to 3 h after the beginning of the photoperiod) as affected by CS (day 4) and PS (day 3, abscissas). Means ± SE (smaller than the symbols) are from SI Appendix, Table S2. (B) Representative images of GUS stained seedlings bearing the pMSG2/IAA19:GUS transgene. (Scale bar = 200 µm.) (C) Auxin levels on day 4 (3 h after the beginning of the photoperiod). Means ± SE of four biological replicates. **P < 0.01; ***P < 0.001.