Control of gibberellin levels and gene expression during de-etiolation in pea.
Gibberellin A(1) (GA(1)) levels drop significantly in wild-type pea (Pisum sativum) plants within 4 h of exposure to red, blue, or far-red light. This response is controlled by phytochrome A (phyA) (and not phyB) and a blue light receptor. GA(8) levels are increased in response to 4 h of red light, whereas the levels of GA(19), GA(20), and GA(29) do not vary substantially. Red light appears to control GA(1) levels by down-regulating the expression of Mendel's LE (PsGA3ox1) gene that controls the conversion of GA(20) to GA(1), and by up-regulating PsGA2ox2, which codes for a GA 2-oxidase that converts GA(1) to GA(8). This occurs within 0.5 to 1 h of exposure to red light. Similar responses occur in blue light. The major GA 20-oxidase gene expressed in shoots, PsGA20ox1, does not show substantial light regulation, but does show up-regulation after 4 h of red light, probably as a result of feedback regulation. Expression of PsGA3ox1 shows a similar feedback response, whereas PsGA2ox2 shows a feed-forward response. These results add to our understanding of how light reduces shoot elongation during de-etiolation.
Reid
James B
JB
School of Plant Science, University of Tasmania, G.P.O. Box 252-55, Hobart, Tasmania, 7001, Australia. Jim.Reid@ufas.edu.au
Botwright
Natasha A
NA
Smith
Jennifer J
JJ
O'Neill
Damian P
DP
Kerckhoffs
L Huub J
LH
D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology / Q000528:radiation effects; D008027:Light; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D010786:Photoreceptor Cells / Q000378:metabolism / Q000528:radiation effects; D010834:Phytochrome / Q000378:metabolism / Q000528:radiation effects; D051942:Phytochrome A; D051939:Phytochrome B; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors
D005875:Gibberellins; D051942:Phytochrome A; D012333:RNA, Messenger; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B; D006899:Mixed Function Oxygenases; C089210:gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing); C121463:gibberellin 2-dioxygenase