The light-induced reduction of the gravitropic growth-orientation of seedlings of Arabidopsis thaliana (L.) Heynh. is a photomorphogenic response mediated synergistically by the far-red-absorbing forms of phytochromes A and B.
Hypocotyls of dark-grown seedlings of Arabidosis thaliana exhibit a strong negative gravitropism, which is reduced by red and also by long-wavelength, far-red light treatments. Light treatments using phytochrome A (phyA)- and phytochrome B (phyB)-deficient mutants showed that this response is controlled by phyB in a red/far-red reversible way, and by phyA in a non-reversible, very-low-fluence response. Crosses of the previously analyzed phyB-1 allele (in the ecotype Landsberg erecta background) to the ecotype Nossen wild-type (WT) background resulted in a WT-like negative gravitropism in darkness, indicating that the previously described gravitropic randomization observed with phyB-1 in the dark is likely due to a second mutation independent of that in the PHYB gene.
Poppe
C
C
Institut für Biologie II, Freiburg, Germany.
Hangarter
R P
RP
Sharrock
R A
RA
Nagy
F
F
Schäfer
E
E
D017360:Arabidopsis; D029681:Arabidopsis Proteins; D018522:Gravitropism; D018546:Hypocotyl; D008027:Light; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D051942:Phytochrome A; D051939:Phytochrome B; D010944:Plants; D014157:Transcription Factors
D029681:Arabidopsis Proteins; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B