Polyamine Metabolism under Different Light Regimes in Wheat

Abstract

Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m–2 s–1) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions.

Light Intensity- and Spectrum-Dependent Redox Regulation of Plant Metabolism

“…Light intensity regulates free amino acid concentration at the transcriptional level, as shown by the increased expression of the genes related to Arg, Glu, Asp, and Ser metabolism. Since Arg is the precursor of polyamines, its light-induced accumulation activates their synthesis, as demonstrated with elevated putrescine and spermidine contents at higher PPFDs in leaves of wheat [ 155 ]. Polyamines, together with certain free amino acids (Pro, Glu, Cys), may have a role in the adaptation to changes in light conditions through their associations with the redox system.…”

Light Spectral Composition Modifies Polyamine Metabolism in Young Wheat Plants

“…PA treatments, namely PUT, SPD, and spermine (SPM) were applied at 0.3 mM concentration only under B, R, and P light regimes. In a previous study, the effects of these PA compounds were investigated under white light conditions at different light intensities [ 57 ]. In the present study PUT, SPD, and SPM treatments were applied only under B, R, and P regimes.…”

“…In our previous study, the effects of PA treatment under white light conditions was investigated under different light intensities, where it was demonstrated that in the leaves, light distinctly induced the PUT level and reduced the DAP content, which suggests that higher light conditions inhibit the terminal catabolism of higher PAs. In addition, exogenous PA treatments influenced the PA metabolism differently under different light intensities [ 57 ]. In the present study the effects of PUT, SPD, and SPM treatments were only investigated under B, R, and P regimes.…”

“…According to these results, it seems that plants try to maintain the same optimal concentration and ratio of PA under different spectral compositions. In addition, the effects of light quantity or time of illumination or the lack of light may be more dominant on the actual PA pool than the light quality [ 32 , 33 , 43 , 54 , 57 ]. However, it should also be taken into consideration that red and far-red light supplementation can result in similar changes as growth under white light conditions, especially under low light intensity [ 33 , 50 ].…”

“…Briefly, light distinctly induced the PUT level and reduced the 1,3-diamino propane (DAP) content in the leaves, the latter result suggesting the inhibition of the terminal catabolism of higher PAs under higher light conditions. In addition, exogenous PA treatments influenced the PA metabolism differently under altered light intensities [ 57 ]. However, despite the above-described information about the relationship between PA metabolism and light, there is still little direct information available about light-influenced PA metabolism.…”