Promotion of growth by elevated carbon dioxide is coordinated through a flexible transcriptional network in Arabidopsis

Abstract

Although gibberellins (GAs) promote many developmental responses in plants, little is known about how the hormone interacts with environmental signals at the molecular level for regulating plant growth. Recently, we have demonstrated that inhibition of growth by the GA biosynthesis inhibitor paclobutrazol (PAC) at ambient [CO₂] (350 µmol CO₂ mol(-1)) is reverted by elevated [CO₂] (750 μmol CO₂ mol(-1)). Our finding points to an important role of elevated [CO₂] as a signal allowing higher growth rates of low-GA plants. GA promotes plant growth via a complex transcriptional network that integrates multiple signaling pathways. Herein, we discuss how elevated [CO₂] stimulates biomass accumulation in a GA-independent manner by regulating the expression of growth-related genes.

Keywords: elevated carbon dioxide concentration; gibberellin; growth; paclobutrazol; transcription factor.

Figure 1. Expression pattern of PREs, PIFs and BR-related genes in shoots of Arabidopsis plants treated with PAC and/or GA₄₊₇ grown at 350 (left) or 750 (right) µmol CO₂ mol^-1 as determined by quantitative RT-PCR. The color scale represents the Log2 fold change values of expression changes compared with control (blue, reduced; yellow, increased). For plants treated at ambient [CO₂], non-treated plants were used as control. For untreated plants at high [CO₂], the relative expression is shown as compared with ambient [CO₂] while expression data for plants treated at high [CO₂] were normalized to non-treated plants at elevated [CO₂]. Data represent means of three independent biological replicates. Heatmap was generated with the MultiExperiment Viewer (MeV) software (www.tm4.org/mev). AGI codes: PRE1 (AT5G39860); PRE2 (AT5G15160); PRE4 (AT3G47710); PRE5 (AT3G28857); PRE6 (AT1G26945); PIF1 (AT2G20180); PIF3 (AT1G09530); PIF4 (AT2G43010); PIF5 (AT3G59060); PIF6 (AT3G62090); PIF7 (AT5G39860); BZR1 (AT1G75080); BZR2 (AT1G19350); IBH1 (AT2G43060); ARL (AT2G44080); DWF4 (AT3G50660); BLH1 (AT2G35940).