Fig. 4. Non-overlapping functions of MP/ARF5 and NPH4/ARF7. (A) Quantification of cotyledon area of light-germinated seedlings of the indicated genotypes at 10 dag, grown in the presence of 0 and 1 µM 2,4-D. Sample sizes are 45 to 50 cotyledons. (B) Hypocotyl length of seedlings of the indicated genotypes germinated and grown in the dark for 5 days in the presence of 20 µM IAA. Sample sizes are 10 to 50 seedlings. On hormone-free media, hypocotyls of all genotypes elongated to 1.2 cm. (C) Transcript abundance of the Aux/IAA genes IAA2 and IAA19 in light-germinated seedlings of the indicated genotypes exposed to 0, 10 and 100 µM IAA at 7 dag for 30 minutes. Transcript abundance from three independent experiments is displayed as multiples of the wild-type level at 0 µM IAA. Columns represent the mean±s.e. (A,C) and s.d. (B).