Figure 9.

phyA acts downstream of AtMDR1 in regulating hypocotyl growth. A, Representative pictures of wild type (Col, Ler), atmdr1-100, phyA-1 single mutants, and atmdr1-100/phyA-1 double mutant grown on germination plates with or without 2.0 μm NPA under far-red light for 4 d. Bar = 1 mm. B, Hypocotyl length of wild type (Col, Ler), atmdr1-100, phyA-1, and atmdr1-100/phyA-1 as shown in A. Bars represent sds from 20 seedlings. C, Hypocotyl orientation of Arabidopsis seedlings grown in the darkness or continuous far-red light for 5 d. The orientation of hypocotyls angle was measured as the sd around the vertical 0°. Values represent the pooled sd for a minimum of 100 seedlings from triplicate experiments. High sds indicate randomization of hypocotyls. D, Root elongation of wild type (Col, Ler), atmdr1-100, phyA-1, and atmdr1-100/phyA-1 mutants under far-red light. Seedlings were vertically grown in far-red for 3 d and then transferred to new plates with (10 nm or 100 nm) or without 1-NAA for further 4 d before the additional root elongation was measured. Bars denote sds from 20 seedlings. For B to D, the plant genotypes are shown in C.