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Phytochrome‐Mediated Inhibition of Coleoptile Growth in Rice: Age‐dependency and Action Spectra †
Author(s) -
Xie Xianzhi,
Shinomura Tomoko,
Inagaki Noritoshi,
Kiyota Seiichiro,
Takano Makoto
Publication year - 2007
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2006-03-17-ra-850
Subject(s) - coleoptile , phytochrome , mutant , phytochrome a , oryza sativa , biology , growth inhibition , biophysics , germination , botany , microbiology and biotechnology , genetics , gene , arabidopsis thaliana , red light , in vitro
Phytochrome has been shown to be the major photoreceptor involved in the photo‐inhibition of coleoptile growth in Japonica‐type rice ( Oryza sativa L.). We have characterized this typical photomorphogenetic response of rice using mutants deficient in phytochrome A (phyA) and phytochrome B (phyB) and with respect to age‐dependency and action spectra. Seedlings were irradiated with a pulse of light 40 h or 80 h after germination ( i.e. at an early or late developmental stage) and the final coleoptile length of these seedlings was determined. A saturating pulse of red light (R) had a stronger effect when it was given in the late stage than in the early stage. It was found that the photo‐inhibition is mediated by both the phyA and the phyB in the late stage but predominantly by phyB in the early stage. Consistent with many other reported responses, the photo‐inhibition in the phyA mutant, which was observed in the early and late developmental stages and is thought to be mediated mainly by phyB, occurred in the low‐fluence range (10 1 –10 3 μmol m −2 ) of R and was far‐red‐light (FR)‐reversible; the photo‐inhibition in the phyB mutant, which was observed in the late developmental stage and is thought to be mediated mainly by phyA, occurred in the very‐low‐fluence range (10 −2 –10 0 μmol m −2 ) and was FR‐irreversible. The action spectra (350–800 nm at 50 nm intervals) obtained at the two developmental stages using phyA and phyB mutants indicated that both the phyB‐mediated low‐fluence response and the phyA‐mediated very‐low‐fluence response have a major peak at 650 nm and a minor peak at 400 nm.