Effect of circularly polarized light on germination, hypocotyl elongation and biomass production of arabidopsis and lettuce: Involvement of phytochrome B

Effects of LED polarized and vortex light on growth and photosynthetic characteristics of pepper (Capsicum annuum L.)

Most studies currently focus on traditional illuminant regulating plant growth, while less attention has been given to the LED internal luminescence. This study examined how polarized and vortex light affect the growth and photosynthetic traits of pepper plants, with LED light used as the control. The findings indicated that circular polarized light significantly increased the aboveground biomass of pepper. Additionally, both polarized and vortex light treatment significantly influenced the root development of pepper. In comparison to the control group, the chlorophyll content was highest under circular polarized light, while the Pn, Sc, Tr, and Ci values were highest under linear polarized light, and the enzyme activity of Rubisco was increased. Circular polarized light notably increased the activities of POD, CAT, and SOD, the activity of SOD reached its peak under the left vortex light. Moreover, the content of MDA was observed to be the lowest under linear and right vortex light treatments. The expressions of key genes for chlorophyll synthesis (CaHEMA1 and CaCAO) and antioxidant enzyme synthesis (CaPOD, CaSOD, and CaMDHAR) were significantly altered under varying polarized light conditions, The latter genes, which play crucial roles in antioxidant enzyme activity, also showed significant variations in response to different polarized light treatments. In conclusion, polarized light significantly impacts the growth of pepper and is anticipated to be utilized for plant growth, setting the stage for future research in this area.

Chiral Tetrakis Eu(III) Complexes with Ammonium Cations for Improved Circularly Polarized Luminescence

Large dissymmetry factor of the circularly polarized luminescence (gCPL) was observed in ligand and coordination tuned chiral tetrakis europium (Eu(III)) complexes with ammonium cations. The gCPL value was estimated to be -1.54, which is the largest among chiral luminescent molecules. Through photophysical measurements, single crystal X-ray structural analyses and quantum chemical calculations, changes in the geometric and electronic structures were observed for a series of chiral tetrakis Eu(III) complexes which enhanced the gCPL value. The emission quantum yield and photosensitized energy transfer efficiencies of chiral Eu(III) complexes with ammonium cations were also larger than those of chiral Eu(III) complex with Cs+. Based on the systematic modifications and analyses for chiral tetrakis Eu(III) complex, effect of the ammonium cation on enhanced CPL brightness is reported.

Phytochrome B enhances seed germination tolerance to high temperature by reducing S-nitrosylation of HFR1

Light and ambient high temperature (HT) have opposite effects on seed germination. Light induces seed germination through activating the photoreceptor phytochrome B (phyB), resulting in the stabilization of the transcription factor HFR1, which in turn sequesters the suppressor PIF1. HT suppresses seed germination and triggers protein S-nitrosylation. Here, we find that HT suppresses seed germination by inducing the S-nitrosylation of HFR1 at C164, resulting in its degradation, the release of PIF1, and the activation of PIF1-targeted SOMNUS (SOM) expression to alter gibberellin (GA) and abscisic acid (ABA) metabolism. Active phyB (phyBY276H ) antagonizes HFR1 S-nitrosylation and degradation by increasing S-nitrosoglutathione reductase (GSNOR) activity. In line with this, substituting cysteine-164 of HFR1 with serine (HFR1C164S ) abolishes the S-nitrosylation of HFR1 and decreases the HT-induced degradation of HFR1. Taken together, our study suggests that HT and phyB antagonistically modulate the S-nitrosylation level of HFR1 to coordinate seed germination, and provides the possibility to enhance seed thermotolerance through gene-editing of HFR1.

Protein-chromophore interactions controlling photoisomerization in red/green cyanobacteriochromes

Photoreceptors in the phytochrome superfamily use 15,16-photoisomerization of a linear tetrapyrrole (bilin) chromophore to photoconvert between two states with distinct spectral and biochemical properties. Canonical phytochromes include master regulators of plant growth and development in which light signals trigger interconversion between a red-absorbing 15Z dark-adapted state and a metastable, far-red-absorbing 15E photoproduct state. Distantly related cyanobacteriochromes (CBCRs) carry out a diverse range of photoregulatory functions in cyanobacteria and exhibit considerable spectral diversity. One widespread CBCR subfamily typically exhibits a red-absorbing 15Z dark-adapted state similar to that of phytochrome that gives rise to a distinct green-absorbing 15E photoproduct. This red/green CBCR subfamily also includes red-inactive examples that fail to undergo photoconversion, providing an opportunity to study protein-chromophore interactions that either promote photoisomerization or block it. In this work, we identified a conserved lineage of red-inactive CBCRs. This enabled us to identify three substitutions sufficient to block photoisomerization in photoactive red/green CBCRs. The resulting red-inactive variants faithfully replicated the fluorescence and circular dichroism properties of naturally occurring examples. Converse substitutions restored photoconversion in naturally red-inactive CBCRs. This work thus identifies protein-chromophore interactions that control the fate of the excited-state population in red/green cyanobacteriochromes.