Physiological and genetic characterization of end-of-day far-red light response in maize seedlings.
Developmental responses associated with end-of-day far-red light (EOD-FR) signaling were investigated in maize (Zea mays subspecies mays) seedlings. A survey of genetically diverse inbreds of temperate and tropical/semitropical origins, together with teosinte (Zea mays subspecies parviglumis) and a modern hybrid, revealed distinct elongation responses. A mesocotyl elongation response to the EOD-FR treatment was largely absent in the tropical/semitropical lines, but both hybrid and temperate inbred responses were of the same magnitude as in teosinte, suggesting that EOD-FR-mediated mesocotyl responses were not lost during the domestication or breeding process. The genetic architecture underlying seedling responses to EOD-FR was investigated using the intermated B73 x Mo17 mapping population. Among the different quantitative trait loci identified, two were consistently detected for elongation and responsiveness under EOD-FR, but none were associated with known light signaling loci. The central role of phytochromes in mediating EOD-FR responses was shown using a phytochromeB1 phytochromeB2 (phyB1 phyB2) mutant series. Unlike the coleoptile and first leaf sheath, EOD-FR-mediated elongation of the mesocotyl appears predominantly controlled by gibberellin. EOD-FR also reduced abscisic acid (ABA) levels in the mesocotyl for both the wild type and phyB1 phyB2 double mutants, suggesting a FR-mediated but PHYB-independent control of ABA accumulation. EOD-FR elongation responses were attenuated in both the wild type and phyB1 phyB2 double mutants when a chilling stress was applied during the dark period, concomitant with an increase in ABA levels. We present a model for the EOD-FR response that integrates light and hormonal control of seedling elongation.
Dubois
Patrice G
PG
Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853, USA.
Olsefski
Gregory T
GT
Flint-Garcia
Sherry
S
Setter
Tim L
TL
Hoekenga
Owen A
OA
Brutnell
Thomas P
TP
D000040:Abscisic Acid / Q000378:metabolism; D003080:Cold Temperature; D003624:Darkness; D005875:Gibberellins / Q000494:pharmacology; D007178:Inbreeding; D008027:Light; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D051939:Phytochrome B / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D040641:Quantitative Trait Loci / Q000235:genetics; D036226:Seedlings / Q000235:genetics* / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D013997:Time Factors; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects
D005875:Gibberellins; D051939:Phytochrome B; D000040:Abscisic Acid; C007842:gibberellic acid