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

Abstract

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 3 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.

Phytochrome A and B Function Antagonistically to Regulate Cold Tolerance via Abscisic Acid-Dependent Jasmonate Signaling

“…These results suggest that ABA and JA are involved in phyAand phyB-mediated cold tolerance that is promoted by FR and suppressed by R conditions, respectively. This is consistent with earlier observations that phytochromes are involved in the regulation of phytohormones in germinating seeds, young seedlings, and shade responses (Sawada et al, 2008;Dubois et al, 2010;Robson et The false color code depicted at the bottom of the image ranges from 0 (black) to 1 (purple). C and D, Relative electrolyte leakage and transcript levels of CBF1 in wild-type and not (C) or spr2 (D) mutant plants as influenced by foliar application of MeJA or ABA.…”

The Interaction of Genotype and Environment Determines Variation in the Maize Kernel Ionome

“…The four rounds of intermating and subsequent inbreeding generated increased recombination and a longer genetic map for the IBM than for typical biparental recombinant inbred line populations. The number of individuals, marker density, and greater recombination facilitates more precise QTL localization than a standard RIL population (Hazen et al 2003; Balint-Kurti et al 2007; Dubois et al 2010; Ordas et al 2010; Zhang et al 2010; Lung’aho et al 2011). This greater resolution reduces the number of genes within a QTL support interval, increasing the utility of QTL mapping as a hypothesis test for shared genetic regulation of multiple traits and promoting discovery of the molecular identity of genes affecting QTL.…”

Seedling development in maize cv. B73 and blue light-mediated proteomic changes in the tip vs. stem of the coleoptile

“…In addition to its use as a major crop plant, maize has been employed as a “green model organism” for basic plant research (Baluska et al 1996, 2010; Edelmann et a. 1995, Edelmann and Roth 2006, Markelz et al 2003, Dubois et al 2010, Borucka and Fellner 2012). In previous studies, we used hybrid maize Liberal (H-L) for the analysis of C4-photosynthesis in the developing primary leaf and auxin action in the coleoptile, respectively (Kutschera et al 2010, Kutschera and Wang 2016).…”