Figure 4.

C. hirsuta sis1 Seedlings Are Impaired in Their Tolerance to Plant Proximity.

(A) Effects of W+FR treatment on PIL1 and ATHB2 expression in Ch^WT sis1-1 and sis1-2 seedlings. Seedlings were grown as in Figure 2D. Transcript abundance, normalized to EF1α, is shown. Values are means and se of three independent RT-qPCR biological replicates relative to values at 0 h for each genotype. Asterisks indicate significant differences (**, P < 0.01) relative to 0-h samples.

(B) Carotenoid (CRT) and chlorophyll (CHL) levels of At^WT and phyA-501 Arabidopsis and Ch^WT, sis1-1, and sis1-2 C. hirsuta seedlings grown in W and W+FR (as detailed in Figure 1A). Values are means and se of five independent samples. Asterisks indicate significant differences (*, P < 0.05 and **, P < 0.01) relative to W-grown plants.

(C) and (D) Hypocotyl length of day-7 At^WT, phyA-501 (Arabidopsis; [C]) and Ch^WT, sis1-1, and sis1-2 (C. hirsuta; [D]) seedlings grown for the last 4 d under the indicated R:FR. Asterisks indicate significant differences (*, P < 0.05 and **, P < 0.01) relative to the corresponding wild-type plant grown under the same R:FR. In (D), asterisks apply for both sis1 mutants.