Light‐ and phytochrome‐mediated gene expression in Douglas‐fir seedlings

Abstract

In dark‐grown Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings, the steady‐state level of the major light‐harvesting chlorophyll a/b binding proteins mRNA (cab mRNA) was about 25% of the level that accumulated in light‐grown seedlings. A single, 5‐min irradiance with red light up‐regulated expression transiently, so that cab mRNAs accumulated to a Jevel approaching that determined for light‐grown seedlings. The response was reversible by far‐red light to the dark level, indicating that the up‐regulation was a phytochrome‐mediated response. Phytochrome action also up‐regulated genes that encode ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39) (rbcS) in Douglas‐fir seedlings, but the maximal rbcS mRNA level that was attained after the red light treatment was several‐fold lower than the expression level deternined for light‐grown seedlings. Genes that produce ubiquitin and ubiquitin‐fusion transcripts were differentially expressed in dark‐ and light‐grown seedlings, but the genes did not appear to be phytochrome regulated.

Developmental and Light-Regulated Expression of Individual Members of the Light-Harvesting Complex b Gene Family in Pinus palustris

“…In common with angiosperm Lhcb genes, the Lhcb genes studied in P. palustris showed a response to LF light but lacked a significant response in the VLF range, the pattern of response for each P. palustris gene differing from that previously reported for the total family in pea (Kaufman et al, 1984) or for individual family members (White et al, 1995). Like P. palustris, Douglas fir Lhcb sequences hybridizing a coding region probe (which could hybridize transcripts from more than one gene) also showed a classical LF response that was fully reversible by far-red light but only 12 h or more after the light treatments (Alosi and Neale, 1992). Since a VLF response for any family member should have been detectable in these experiments, the Douglas fir Lhcb genes may also lack a VLF response, and it is possible that Lhcb gene expression does not show a VLF response in conifers.…”

“…Expression of Lhcb sequences in darkness has been shown to occur in Douglas fir (Alosi et al, 1990), P. thunbergii (Yamamoto et al, 1991(Yamamoto et al, , 1993Kojima et al, 1992), and in members of the Taxodiaceae and Cupressaceaea, which show light-independent chloroplast development (Mukai et al, 1992). In Douglas fir the dark levels of Lhcb mRNA were about 25 to 30% of the light levels (Alosi et al, 1990;Alosi and Neale, 1992). In pines each type of Lhcb apparently showed a similar level and pattern of expression between species.…”

Phytochrome Signaling Is Mediated by PHYTOCHROME INTERACTING FACTOR in the Liverwort Marchantia polymorpha

“…Recent phylogenetic analyses demonstrate that plant phytochromes were acquired in the last common ancestor of Archaeplastida and that the canonical plant phytochromes originated in an ancestor of streptophytes (Duanmu et al, 2014;Li et al, 2015). Although R/FR photoreversible responses and the distribution of phytochrome genes have been reported in several angiosperms (Mancinelli, 1994), gymnosperms (Alosi and Neale, 1992;Christensen et al, 2002;Mølmann et al, 2006), ferns (Haupt, 1985;Tsuboi et al, 2012), bryophytes (Hartmann and Jenkins, 1984), and charophytes (Weisenseel and Ruppert, 1977;Sokol and Stross, 1992), little is known about the molecular mechanisms of phytochrome signaling apart from those of Arabidopsis. In this study, we found that phytochrome signaling in a liverwort is mediated by a single PIF transcription factor.…”

“…Recent analysis has shown that light-activated phytochromes interact with the SPA family in a lightdependent manner and promote the dissociation of the COP1/ SPA complex (Lu et al, 2015;Sheerin et al, 2015). Phytochromedependent regulation of gene expression has also been reported in several angiosperms (Sawers et al, 2002;Takano et al, 2005;Kebrom et al, 2006;Takano et al, 2009;Kebrom et al, 2010) and gymnosperms (Alosi and Neale, 1992;Christensen et al, 2002). However, the molecular mechanisms of R-mediated transcriptional regulation in these species are still poorly understood.…”

Clock genes and diurnal transcriptome dynamics in summer and winter in the gymnosperm Japanese cedar ( Cryptomeria japonica (L.f.) D.Don)

“…In conifers, light-independent expression of photosynthetic genes seems to be a general phenomenon [64]. Lhcb and psbA (photosystem II subunit A) mRNA levels show only small diurnal fluctuations under light/dark cycles and no circadian rhythm under continuous light or dark conditions in Douglas fir (Pseudotsuga menziesii) [65]. By analyzing dark-grown seedlings, expression of Lhcb genes has been shown to occur in darkness in various conifer species [64][65][66][67][68][69].…”