Abstract
Loss-of-function mutants of NPH4 are insensitive to auxin and have defects in hypocotyl tropism, hook formation, differential growth of leaf and lateral root formation. We carried out screening of suppressor mutants of nph4 from a M2 population of EMS-mutagenized nph4-103 by checking hyponastic growth of cotyledon and rosette leaf. In the second screening, we selected mutants that exhibited restored tropism of hypocotyl. Finally, we isolated 3 suppressor lines. All of them are recessive. One of them displayed epinastic leaves and restored gravitropism of hypocotyl; defects in phototropism were not restored. Another line was dwarf with dark green leaves and exhibited de-etiolated phenotype in the dark. Gravi- and phototropism were normal until 4 h from the start of stimulation. The other line was semi-dwarf with dark green leaves, and showed slight recovery of gravitropic defects, but no restoration in phototropism.
