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Background Cunninghamia lanceolata (C. lanceolata) is the main fast-growing timber species in southern China. As an alternative to conventional lighting systems, LED has been demonstrated to be an artificial flexible lighting source for commercial micropropagation. The application of LED can provide rapid propagation of C. lanceolata in vitro culture. Results We applied two-factor randomized block design to study the effects of LED photoperiods and light qualities on the growth and chlorophyll fluorescence of C. lanceolata in vitro culture plantlets. In this study, plantlets were exposed to 20 μmol·m − 2 ·s − 1 irradiance for three photoperiods, 8, 16, and 24 h under the three composite lights, 88.9% red+ 11.1% blue (R/B), 80.0% red+ 10.0% blue+ 10.0% purple (R/B/P), 72.7% red+ 9.1% blue+ 9.1% purple+ 9.1% green (R/B/P/G), as well as white light (12.7% red+ 3.9% blue+ 83.4% green, W) as control. The results showed that: (1) Plant height, dry weight, rooting rate, average root number, length, surface area and volume, chlorophyll, and chlorophyll fluorescence parameters were significantly affected by photoperiods, light qualities and their interactions. (2) Plantlets subjected to photoperiod 16 h had longer root, higher height, rooting rate, root number, and the higher levels of chlorophyll, chlorophyll a/b, Y (II), qP, NPQ/4 and ETR II compared to photoperiods 8 h and 24 h, while Fv/Fm during photoperiod 16 h was lower than 8 h and 24 h. Plantlets exposed to R/B/P/G generated more root and presented higher chlorophyll, Fv/Fo, Y (II), qP, and ETR II than W during photoperiods 8 and 16 h. (3) Total chlorophyll content and ETR II were significant correlated with rooting rate, root length and root volume, while Fv/Fm and ETR II were significant correlated with plant height, average root number and root surface area. (4) 16-R/B/P/G is best for growing C. lanceolata plantlets in vitro. Conclusions This study demonstrated the effectiveness of photoperiods and light qualities using LEDs for micropropagation of C. lanceolata . The best plantlets were harvested under 16-R/B/P/G treatment. And there was a correlation between the growth and the chlorophyll and chlorophyll fluorescence of their leaves under different photoperiod and light quality. These results can contribute to improve the micropropagation process of this species.

Cryptophyte algae are an evolutionarily distinct and ecologically important group of photosynthetic unicellular eukaryotes. Photosystem II (PSII) of cryptophyte algae associates with alloxanthin chlorophyll a/c -binding proteins (ACPs) to act as the peripheral light-harvesting system, whose supramolecular organization is unknown. Here, we purify the PSII-ACPII supercomplex from a cryptophyte alga Chroomonas placoidea ( C. placoidea ), and analyze its structure at a resolution of 2.47 Å using cryo-electron microscopy. This structure reveals a dimeric organization of PSII-ACPII containing two PSII core monomers flanked by six symmetrically arranged ACPII subunits. The PSII core is conserved whereas the organization of ACPII subunits exhibits a distinct pattern, different from those observed so far in PSII of other algae and higher plants. Furthermore, we find a Chl a -binding antenna subunit, CCPII-S, which mediates interaction of ACPII with the PSII core. These results provide a structural basis for the assembly of antennas within the supercomplex and possible excitation energy transfer pathways in cryptophyte algal PSII, shedding light on the diversity of supramolecular organization of photosynthetic machinery. The authors report structure of PSII-ACPII from a cryptophyte alga Chroomonas placoidea , providing insights into a distinct supramolecular organization and assembly of antennas in the supercomplex and possible excitation energy transfer pathways.

Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. Among Chls functioning in oxygenic photosynthesis, Chl f is the most red-shifted type first found in a cyanobacterium Halomicronema hongdechloris. The location and function of Chl f in photosystems are not clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from H. hongdechloris grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 Chl a and 7 Chl f, and Chl f are associated at the periphery of PSI but not in the electron transfer chain. The appearance of Chl f is well correlated with the expression of PSI genes induced under far-red light. These results indicate that Chl f functions to harvest the far-red light and enhance uphill energy transfer, and changes in the gene sequences are essential for the binding of Chl f.

Main conclusionIn this review, we summarize how chlorophyll metabolism in angiosperm is affected by the environmental factors: light, temperature, metal ions, water, oxygen, and altitude.The significance of chlorophyll (Chl) in plant leaf morphogenesis and photosynthesis cannot be overstated. Over time, researchers have made significant advancements in comprehending the biosynthetic pathway of Chl in angiosperms, along with the pivotal enzymes and genes involved in this process, particularly those related to heme synthesis and light-responsive mechanisms. Various environmental factors influence the stability of Chl content in angiosperms by modulating Chl metabolic pathways. Understanding the interplay between plants Chl metabolism and environmental factors has been a prominent research topic. This review mainly focuses on angiosperms, provides an overview of the regulatory mechanisms governing Chl metabolism, and the impact of environmental factors such as light, temperature, metal ions (iron and magnesium), water, oxygen, and altitude on Chl metabolism. Understanding these effects is crucial for comprehending and preserving the homeostasis of Chl metabolism.

Salinity stress adversely affects wheat growth and productivity, necessitating effective mitigation strategies. This study investigates the combined impact of ascorbic acid (AsA), silver nanoparticles (NPs), and Salvadora oleoides aqueous leaf extract (LE) on wheat tolerance to salinity stress. A randomized complete design (RCD) was employed with fourteen treatments: T1 (5 mM AsA), T2 (10 mM AsA), T3 (20 ppm AgNPs), T4 (40 ppm AgNPs), T5 (5% S. oleoides LE), T6 (10% S. oleoides LE), T7 (20 ppm AgNPs + 5 mM AsA), T8 (20 ppm AgNPs + 10 mM AsA), T9 (40 ppm AgNPs + 5 mM AsA), T10 (40 ppm AgNPs + 10 mM AsA), T11 (20 ppm AgNPs + 5% S. oleoides LE), T12 (20 ppm AgNPs + 10% S. oleoides LE), T13 (40 ppm AgNPs + 5% S. oleoides LE), and T14 (40 ppm AgNPs + 10% S. oleoides LE). Wheat plants were subjected to salinity stress (SS) and no-stress conditions (NoSS) for 50 days. Chlorophyll content, DPPH activity, total soluble proteins and sugars, antioxidant enzyme activities, lipid peroxidation, leaf ion concentrations, and nutrient uptake were analyzed. Under SS, T6 (10% LE) showed the lowest chlorophyll-a (90.04%) and b (57.84%). DPPH activity was highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) at 14.40%, and lowest in SS with T6 (10% LE) at 6.67%. Total soluble proteins and sugars were highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) and T6 (10% LE). In SS, SOD activity peaked with T6 (10% LE) at 8.39 U/mg protein, while CAT activity was highest with T9 (40 ppm NPs + 5 mM AsA) at 6.25 U/mg protein. Lipid peroxidation was highest in SS with T6 (10% LE) at 14.67 µM MDA/g fresh weight. Leaf Na and Cl concentrations were highest in SS with T9 (40 ppm NPs + 5 mM AsA), at 14.26% and 44.15%, respectively. The combined application of 40 NPs and 5 AsA (T9) proved most effective in enhancing chlorophyll content and DPPH activity under NoSS, while 10% LE (T6) showed significant improvements in SOD activity and lipid peroxidation mitigation under SS. Future research should explore optimizing treatment concentrations and combinations to further enhance wheat stress tolerance and evaluate long-term effects on crop yield and quality.

Canola, a vital oilseed crop, is grown globally for food and biodiesel. With the enormous demand for growing various crops, the utilization of agriculturally marginal lands is emerging as an attractive alternative, including brackish-saline transitional lands. Salinity is a major abiotic stress limiting growth and productivity of most crops, and causing food insecurity. Salicylic acid (SA), a small-molecule phenolic compound, is an essential plant defense phytohormone that promotes immunity against pathogens. Recently, several studies have reported that SA was able to improve plant resilience to withstand high salinity. For this purpose, a pot experiment was carried out to ameliorate the negative effects of sodium chloride (NaCl) on canola plants through foliar application of SA. Two canola varieties Faisal (V1) and Super (V2) were assessed for their growth performance during exposure to high salinity i.e. 0 mM NaCl (control) and 200 mM NaCl. Three levels of SA (0, 10, and 20 mM) were applied through foliar spray. The experimental design used for this study was completely randomized design (CRD) with three replicates. The salt stress reduced the shoot and root fresh weights up to 50.3% and 47% respectively. In addition, foliar chlorophyll a and b contents decreased up to 61–65%. Meanwhile, SA treatment diminished the negative effects of salinity and enhanced the shoot fresh weight (49.5%), root dry weight (70%), chl. a (36%) and chl. b (67%). Plants treated with SA showed an increased levels of both enzymatic i.e. (superoxide dismutase (27%), peroxidase (16%) and catalase (34%)) and non-enzymatic antioxidants i.e. total soluble protein (20%), total soluble sugar (17%), total phenolic (22%) flavonoids (19%), anthocyanin (23%), and endogenous ascorbic acid (23%). Application of SA also increased the levels of osmolytes i.e. glycine betaine (31%) and total free proline (24%). Salinity increased the concentration of Na + ions and concomitantly decreased the K + and Ca 2+ absorption in canola plants. Overall, the foliar treatments of SA were quite effective in reducing the negative effects of salinity. By comparing both varieties of canola, it was observed that variety V2 (Super) grew better than variety V1 (Faisal). Interestingly, 20 mM foliar application of SA proved to be effective in ameliorating the negative effects of high salinity in canola plants.

Drought, a prevalent abiotic stressor, significantly impacts plant yield and quality. Melatonin (MT), a potent and economical growth regulator, plays a pivotal role in augmenting crop resilience against stress. This study investigated the efficacy of exogenous MT on drought-stressed celery seedlings by comprehensively analyzing phenotypic, physiological, and molecular attributes. The results revealed that exogenous MT mitigated celery seedling damage under drought stress, lowered malondialdehyde (MDA) concentrations, elevated oxidase activities, osmolyte levels, chlorophyll content, and augmented light energy conversion efficiency. Transcriptomic analysis demonstrated that MT could regulate chlorophyll synthesis genes ( AgPORA1 and AgDVR2 ), contributing to heightened photosynthetic potential and increased drought tolerance in celery. Moreover, MT was found to modulate glycolytic pathways, upregulate pyruvate synthesis genes ( AgPEP1 and AgPK3 ), and downregulate degradation genes ( AgPDC2 and AgPDHA2 ), thereby promoting pyruvate accumulation and enhancing peroxidase activity and drought tolerance. The RNA-seq and qRT-PCR analyses demonstrated similar results, showing the same general expression trends. The study elucidates the physiological and molecular mechanisms underlying MT’s stress-alleviating effects in celery seedlings, offering insights into MT-based strategies in plant cultivation and breeding for arid environments.

As one of the most salt-sensitive crops, strawberry production is severely limited by salt stress. γ--aminobutyric acid (GABA) has been reported to play an important role in the immune response of plants. In this study, the physiological and transcriptomic changes in strawberry seedlings treated with GABA under salt stress were investigated to explore the effect of GABA on salt tolerance. The results showed that exogenous GABA maintained high osmolyte levels, increased antioxidant capacity, and decreased the ROS levels in strawberry leaves under salt stress; the MDA was reduced by 3.27–31.46%, with 10 mM being the most significant effect; the total (Spd + Spm)/ Put ratio was upregulated after GABA treatments. More strikingly, the plants treated with 10 mM GABA significantly increased chlorophyll content and net photosynthetic rate in salt-stressed plants, which was explained by the transcriptomic data showing that the expression levels of most of chlorophyll metabolism and photosynthesis-related genes were upregulated. Furthermore, 38 potential TFs belonging to the WRKY, AP2/ERF, and MYB families were identified that may be positively involved in GABA-induced salt tolerance. Co-expressed network analysis revealed that some of these TFs, such as RAP2.7, WRKY46, and MYB306, were significantly positively correlated with chlorophyll metabolism. These findings provide an important basis for the use of GABA in the breeding of strawberry resistant to salt stress.

Our multi-omics investigation of pepper fruit coloration dynamics demonstrates that the coordinated regulation of flavonoid accumulation and chlorophyll retention underpins the distinct pigmentation patterns between dark green (XHB) and light green (QL2017) cultivars. Through the integrated analysis of three developmental stages (10–30 DPA), we identified 989 differentially accumulated metabolites (DAMs) and 810 differentially expressed genes (DEGs), with flavonoid biosynthesis, phenylpropanoid metabolism, and chlorophyll turnover pathways pinpointed as central regulatory hubs. Notably, key metabolites such as quercitrin, kaempferol-3-O-rhamnoside, and cinnamic acid were significantly enriched in dark green fruits (XHB), coinciding with enhanced antioxidant activity and delayed chlorophyll degradation. Transcriptomic data revealed the coordinated upregulation of chlorophyll biosynthesis genes (COX15, POR) and light-harvesting complex components (Lhcb1, Lhcb2), while PAO—a pivotal chlorophyll catabolism gene—also exhibited elevated expression. Co-expression network analysis highlighted scopoletin GTase, F5H, CCR, and CAD as hub genes regulating flavonoid biosynthesis. qRT-PCR validation confirmed high consistency with transcriptomic trends (r > 0.85, p < 0.01). Our findings propose a synergistic model wherein flavonoid accumulation and chlorophyll metabolic dynamics jointly orchestrate green fruit pigmentation, offering novel insights and molecular targets for the precision breeding of pepper fruit coloration.

Tea plants are a perennial crop with significant economic value. Chlorophyll, a key factor in tea leaf color and photosynthetic efficiency, is affected by the photoperiod and usually exhibits diurnal and seasonal variations. In this study, high-throughput transcriptomic analysis was used to study the chlorophyll metabolism, under different photoperiods, of tea plants. We conducted a time-series sampling under a skeleton photoperiod (6L6D) and continuous light conditions (24 L), measuring the chlorophyll and carotenoid content at a photoperiod interval of 3 h (24 h). Transcriptome sequencing was performed at six time points across two light cycles, followed by bioinformatics analysis to identify and annotate the differentially expressed genes (DEGs) involved in chlorophyll metabolism. The results revealed distinct expression patterns of key genes in the chlorophyll biosynthetic pathway. The expression levels of CHLE (magnesium-protoporphyrin IX monomethyl ester cyclase gene), CHLP (geranylgeranyl reductase gene), CLH (chlorophyllase gene), and POR (cytochrome P450 oxidoreductase gene), encoding enzymes in chlorophyll synthesis, were increased under continuous light conditions (24 L). At 6L6D, the expression levels of CHLP1.1, POR1.1, and POR1.2 showed an oscillating trend. The expression levels of CHLP1.2 and CLH1.1 showed the same trend, they both decreased under light treatment and increased under dark treatment. Our findings provide potential insights into the molecular basis of how photoperiods regulate chlorophyll metabolism in tea plants.