Physiological and Genetic Characterization of End-of-Day Far-Red Light Response in Maize Seedlings

• Published in: Plant physiology (Bethesda) 2010-09, Vol.154 (1), p.173-186
• Main Authors: Dubois, Patrice G, Olsefski, Gregory T, Flint-Garcia, Sherry, Setter, Tim L, Hoekenga, Owen A, Brutnell, Thomas P
• Format: Article
• Language: English
• Subjects: Abscisic Acid - metabolism; Agronomy. Soil science and plant productions; Biological and medical sciences; Cold Temperature; Coleoptiles; Corn; Darkness; DEVELOPMENT AND HORMONE ACTION; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Gibberellins - pharmacology; Inbreeding; Leaf sheaths; Light; Mesocotyls; Models, Biological; Mutation - genetics; Organ Specificity - drug effects; Organ Specificity - genetics; Organ Specificity - radiation effects; Phenotypic traits; Phytochrome B - metabolism; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant Leaves - radiation effects; Plant physiology and development; Plants; Population genetics; Quantitative trait loci; Quantitative Trait Loci - genetics; Seedlings; Seedlings - genetics; Seedlings - growth & development; Seedlings - physiology; Seedlings - radiation effects; Seeds - drug effects; Seeds - genetics; Seeds - radiation effects; Time Factors; Zea mays - genetics; Zea mays - growth & development; Zea mays - physiology; Zea mays - radiation effects
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.110.159830

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.