Light Regulation of Gibberellin Biosynthesis in Pea Is Mediated through the COP1/HY5 Pathway

Abstract

Light regulation of gibberellin (GA) biosynthesis occurs in several species, but the signaling pathway through which this occurs has not been clearly established. We have isolated a new pea (Pisum sativum) mutant, long1, with a light-dependent elongated phenotype that is particularly pronounced in the epicotyl and first internode. The long1 mutation impairs signaling from phytochrome and cryptochrome photoreceptors and interacts genetically with a mutation in LIP1, the pea ortholog of Arabidopsis thaliana COP1. Mutant long1 seedlings show a dramatic impairment in the light regulation of active GA levels and the expression of several GA biosynthetic genes, most notably the GA catabolism gene GA2ox2. The long1 mutant carries a nonsense mutation in a gene orthologous to the ASTRAY gene from Lotus japonicus, a divergent ortholog of the Arabidopsis bZIP transcription factor gene HY5. Our results show that LONG1 has a central role in mediating the effects of light on GA biosynthesis in pea and demonstrate the importance of this regulation for appropriate photomorphogenic development. By contrast, LONG1 has no effect on GA responsiveness, implying that interactions between LONG1 and GA signaling are not a significant component of the molecular framework for light–GA interactions in pea.

TheCOP1OrthologPPSRegulates the Juvenile–Adult and Vegetative–Reproductive Phase Changes in Rice

“…LIP1, a pea (Pisum sativum) ortholog of COP1, was recently reported to positively regulate GA biosynthesis through negative regulation of LONG1, an ortholog of the COP1 target HY5, which negatively regulates GA biosynthesis (Weller et al, 2009). This case is comparable with that of PPS.…”

The PeaGIGASGene Is aFLOWERING LOCUS THomolog Necessary for Graft-Transmissible Specification of Flowering but Not for Responsiveness to Photoperiod

“…Two technical replicates and two to three biological replicates were performed for each sample. Transcript levels of several potential reference genes, including EF1a (Johnson et al, 2006), UBI (Platten et al, 2005), and ACTIN (Weller et al, 2009a), were examined in the different tissue series. Of these genes, ACTIN was found to be the most stably expressed, and this gene was therefore used to evaluate transcript levels of flowering genes, as previously described (Weller et al, 2009a).…”

Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both!

“…GA biosynthesis is highly regulated by exogenous stimuli (Stavang et al, 2005(Stavang et al, , 2010Weller et al, 2009), which must be taken into account when GA-related phenotypes are studied. For example, in BR mutants, a 4˚C treatment fully recovered germination defects (Unterholzner et al, 2015), indicating that cold may act independently of BRs to induce GA biosynthesis during germination.…”