Figure 6.

PhyB^Y276Q Is a Constitutively Active Phytochrome, whereas phyB^Y276I Requires Light for Function and phyB^Y276R Is Inactive.

(A) Comparative phenotypic analysis of various lines expressing Y^GAF alleles of PHYB in 6-d-old dark-grown seedlings on sucrose-free MS medium. One representative line from each transformation is shown.

(B) Comparative fluence response curves for hypocotyl growth indicate that phyB^Y276H-mediated growth suppression is red light independent, while the growth suppression activities of phyB^Y276Q and phyB^Y276I are fluence rate dependent and phyB^Y276R is inactive. Each data point represents the mean of 50 seedlings ± sd.

(C) Mean hypocotyl lengths (± sd; n = 50) of 6-d-old seedlings grown under 20 μmol m⁻² s⁻¹ of continuous red light (24h R) or 8-h-R/16-h-dark photoperiods are shown.