Photosynthesis-related Genes Research Articles

RNA-seq analysis reveals genes associated with Macrophomina phaseolina-induced host senescence in soybean

BackgroundCharcoal rot of soybean is caused by the hemibiotrophic fungus Macrophomina phaseolina, a global crop destroyer and an important pathogen in the midwestern USA. The quantitative nature of host resistance and the complexity of the soybean-M. phaseolina interaction at the molecular level have hampered resistance breeding. A previous study showed that L-ascorbic acid (LAA) pre-treatment before M. phaseolina inoculation reduced charcoal rot lesion length in excised soybean stems. This study aimed to elucidate the genetic underpinnings of M. phaseolina-induced senescence and the mitigating effects of ascorbic acid on this physiological process within the same pathosystem.ResultsRNA was sequenced from M. phaseolina-resistant and -susceptible soybean genotypes following M. phaseolina inoculation, LAA, and hydrogen peroxide (H2O2)—an oxidative stress inducer—application followed by inoculation. More genes were down-regulated in the resistant and susceptible genotypes than up-regulated when the M. phaseolina-inoculated treatments were compared to mock-inoculated control treatments. Gene ontology (GO) term and KEGG pathways analysis detected M. phaseolina-induced up-regulation of receptor-like kinase genes. In contrast, many genes related to antioxidants, defense, and hormonal pathways were down-regulated in both genotypes. LAA pre-treatment induced genes related to photosynthesis and reactive oxygen species responses in both genotypes. H2O2 pre-treatment following inoculation up-regulated many stress-response genes, while hormone signal transduction and photosynthesis-related genes were down-regulated in both genotypes.ConclusionsResults revealed transcriptional variation and genes associated with M. phaseolina-induced senescence in soybean. Ascorbic acid induced many photosynthetic genes, suggesting a complex regulation of defense and immunity in the plant against the hemibiotroph. Soybean plants also exhibited enhanced stress responsiveness when treated with H2O2 followed by inoculation with M. phaseolina. This study will broaden more research avenues related to transcriptional regulation during the M. phaseolina-soybean interaction and the potential role of receptor-like kinases, oxidative stress-responsive genes, ethylene-mediated signaling and enhanced photosynthetic gene expression when mounting host resistance to this important soybean pathogen.

Effect of light intensity on nitrogen removal, enzymatic activity and metabolic pathway of algal-bacterial symbiosis in rotating biological contactor treating mariculture wastewater.

An algal-bacterial symbiosis (ABS) system was developed on a rotating biological contactor treating mariculture wastewater, and its nitrogen removal, enzymatic activity and metabolic pathways were investigated under different light intensities. The nitrogen removal efficiency increased when light intensities ranged from 20 to 80 μE/(m2·s) but declined under 100 μE/(m2·s). Higher enzymatic activities under 80 μE/(m2·s) facilitated nitrogen conversion, light utilization, ATP supply and photosynthesis. Reactive oxygen species accumulation activated antioxidant pathways under 20 and 100 μE/(m2·s). Functional bacteria including Sedimentitalea, Thauera and Dechloromonas as well as Chlorella sorokinian, Dunaliella, Pleurosira laevis and Microcystis were enriched under 80 μE/(m2·s). Abundant photosynthesis-related genes (petC, Lca3/4 and atpH/A) supported energy supply and electron transport. Conversely, lower proportions of IDH3, gltB, and acnA/B under 20 and 100 μE/(m2·s) hindered tricarboxylic acid cycle, reducing NADPH and energy production. These results enhance the understanding on the effect of light intensity on ABS system treating mariculture wastewater.

Novel resources to investigate leaf plasmodesmata formation in C3 and C4 monocots.

Plasmodesmata (PD) are nanochannels that facilitate cell-to-cell transport in plants. More productive and photosynthetically efficient C4 plants form more PD at the mesophyll (M)-bundle sheath (BS) interface in their leaves than their less efficient C3 relatives. In C4 leaves, PD play an essential role in facilitating the rapid metabolite exchange between the M and BS cells to operate a biochemical CO2 concentrating mechanism, which increases the CO2 partial pressure at the site of Rubisco in the BS cells and hence photosynthetic efficiency. The genetic mechanism controlling PD formation in C3 and C4 leaves is largely unknown, especially in monocot crops, due to the technical challenge of quantifying these nanostructures with electron microscopy. To address this issue, we have generated stably transformed lines of Oryza sativa (rice, C3) and Setaria viridis (setaria, C4) with fluorescent protein-tagged PD to build the first spatiotemporal atlas of leaf pit field (cluster of PD) density in monocots without the need for electron microscopy. Across leaf development, setaria had consistently more PD connections at the M-BS wall interface than rice while the difference in M-M pit field density varied. While light was a critical trigger of PD formation, cell type and function determined leaf pit field density. Complementary temporal mRNA sequencing and gene co-expression network analysis revealed that the pattern of pit field density correlated with differentially expressed PD-associated genes and photosynthesis-related genes. PD-associated genes identified from our co-expression network analysis are related to cell wall expansion, translation and chloroplast signalling.

Transcriptome and Physiological Analyses of Resistant and Susceptible Pepper (Capsicum annuum) to Verticillium dahliae Inoculum

Pepper (Capsicum annuum) is a globally important vegetable, and Verticillium wilt is an important disease affecting peppers and is caused by Verticillium dahliae, which can severely reduce yields. However, the molecular mechanisms underlying the responses of pepper to infection by V. dahliae are largely unknown. We performed physiological and transcriptome analysis using resistant and susceptible pepper cultivars inoculated with V. dahliae. Compared to the susceptible cultivar MS66, the resistant cultivar MS72 retained higher chlorophyll content and lower malondialdehyde content after inoculation. At 3 days after inoculation (DAI), compared with MS66, 534 differentially expressed genes (DEGs) were identified in MS72. At 5 DAI, 2392 DEGs were identified in MS72 compared with MS66. The DEGs in MS72 were mainly enriched in the cell wall and photosynthesis-related Gene Ontology terms, as well as in pathways such as cutin, suberin, wax biosynthesis, phenylpropanoid biosynthesis, and photosynthesis. Using weighted gene co-expression network analysis, 36 hub genes involved in the resistance response were identified, including the transcription factor bHLH93 (Capana04g000815), defense-like protein 1 (MSTRG.5904), and miraculin-like (Capana10g002167). Our findings contribute to a more comprehensive understanding of the response mechanism of pepper to V. dahliae inoculation, providing new avenues for improving pepper resistance through breeding programs.

Coexpression Regulation of New and Ancient Genes in the Dynamic Transcriptome Landscape of Stem and Rhizome Development in "Bainianzhe"-An Ancient Chinese Sugarcane Variety Ratooned for Nearly 300 Years.

The sucrose yield in sugarcane largely depends on stem morphology, including length, diameter and sugar content, making sugarcane stem a key trait in breeding. The "Bainianzhe" variety from Songxi County, Fujian Province, possesses both aerial stems and rhizomes, providing a unique model for studying stem development. We performed a spatiotemporal transcriptomic analysis of the base, middle and apical sections of both aerial stems and rhizomes. The analysis categorized transcriptomes by developmental stage-base, middle and apical-rather than environmental differences. Apical segments were enriched with genes related to cell proliferation, while base segments were linked to senescence and fibrosis. Gene regulatory networks revealed key TFs involved in stem development. Orphan genes may be involved in rhizome development through coexpression networks. Plant hormones, especially genes involved in ABA and GAs synthesis, were highly expressed in rhizomes. Thiamine-related genes were also more prevalent in rhizomes. Furthermore, the apical segments of rhizomes enriched in photosynthesis-related genes suggest adaptations to light exposure. Low average temperatures in Songxi have led to unique cold acclimation in Bainianzhe, with rhizomes showing higher expression of genes linked to unsaturated fatty acid synthesis and cold-responsive calcium signalling. This indicates that rhizomes may have enhanced cold tolerance, aiding in the plant's overwintering success.

Integrating Biofertilizers with Organic Fertilizers Enhances Photosynthetic Efficiency and Upregulates Chlorophyll-Related Gene Expression in Rice

Biofertilizers offer a sustainable method for improving rice growth and productivity, yet their effects on the interaction between plant growth, photosynthetic activity, and gene expression remain under-researched. This study examines how biofertilizer influences rice physiology, focusing on photosynthetic regulation and expression of chlorophyll-related genes. Eight fertilizer treatments were applied: control (CNT), biofertilizer (BF), deactivated biofertilizer (DABF), rice straw (RS), rice straw with biofertilizer (RS+BF), organic fertilizer (OF), organic fertilizer with biofertilizer (OF+BF), and inorganic fertilizer (IOF). Plant height, tiller number, SPAD, NDVI, chlorophyll content, and photosynthesis rates were measured, while gene expression analysis was conducted using RT-qPCR. The OF+BF treatment produced the most significant results, leading to a 31% increase in plant height, a 135% increase in tiller number, and a 42% increase in chlorophyll content (SPAD values) compared to the control. Additionally, OF+BF enhanced photosynthetic efficiency by 74%, with the highest net photosynthetic rate of 48.23 μmol CO2 m−2 s−1. Gene expression analysis revealed that OF+BF upregulated key photosynthesis-related genes, such as OsChlD and OsCHLM, showing a 70% and 90% increase in expression. These findings highlight the potential of integrating biofertilizers with organic fertilizers to sustainably boost rice growth and productivity, contributing to global food security and climate change mitigation.

Nanoenabled Antiviral Pesticide for Tobacco Mosaic Virus: Excellent Adhesion Performance and Strong Inhibitory Effect to Alleviate the Damage on Photosynthetic System.

Tobacco mosaic virus (TMV) is a major agricultural threat. Here, a cationic star polymer (SPc) was designed to construct an efficient nanodelivery system for moroxydine hydrochloride (ABOB). ABOB could self-assemble with SPc via a hydrogen bond and van der Waals force, and this complexation reduced the particle size of ABOB from 2406 to 45 nm. With the aid of SPc, the contact angle of ABOB decreased from 100.8 to 79.0°, and its retention increased from 6.3 to 13.8 mg/cm2. Furthermore, the complexation with SPc could attenuate the degradation of ABOB in plants, and the bioactivity of SPc-loaded ABOB significantly improved with a reduction in relative viral expression from 0.57 to 0.17. The RNA-seq analysis revealed that the ABOB/SPc complex could up-regulate the expression of growth- and photosynthesis-related genes in tobacco seedlings, and the chlorophyll content increased by 2.5 times. The current study introduced an efficient nanodelivery system to improve the bioactivity of traditional antiviral agents.

Muti-omics revealed the mechanisms of MT-conferred tolerance of Elymus nutans Griseb. to low temperature at XiZang

BackgroundLow temperature seriously limited the development of grass and crops in plateau. Thus, it is urgent to develop an effective strategy for improving the plant cold tolerance and elucidate the underlying mechanisms.ResultsWe found that MT alleviated the effects of cold stress on suppressing ENG growth, then improved cold tolerance of ENG. Integration of transcriptome and metabolome profiles showed that both cold exposure (TW) and MT reprogrammed the transcription pattern of galactose and flavonoids biosynthesis, leading to changes in compositions of soluble sugar and flavonoids in ENG. Additionally, TW inhibited the photosynthesis, and destroyed the antioxidant system of ENG, leading to accumulation of oxidant radicals represented by MDA. By contrast, MT promoted activities of antioxidant enzymes and flavonoid accumulation in ENG under cold condition, then reduced the MDA content and maintained normal expression of photosynthesis-related genes in ENG even under TW. Importantly, MT mainly enhanced cold tolerance of ENG via activating zeatin synthesis to regulate flavonoid biosynthesis in vivo. Typically, WRKY11 was identified to regulate MT-associated zeatin synthesis in ENG via directly binding on zeatin3 promoter.ConclusionsMT could enhance ENG tolerance to cold stress via strengthening antioxidant system and especially zeatin synthesis to promote accumulation of flavonoids in ENG. Thus, our research gain insight into the global mechanisms of MT in promoting cold tolerance of ENG, then provided guidance for protecting plant from cold stress in plateau.

Application of oxide nanoparticles mitigates the salt-induced effects on photosynthesis and reduces salt injury in Cyclocarya paliurus

Salinization is very detrimental to photosynthetic processes and plant growth, while nanoparticles (NPs) are considered to be the emerging materials to improve plant adaptability to salt stress. Cyclocarya paliurus is being planted on saline-alkali soils to meet the growing demand for its leaves and medicinal products. However, this species exhibits low salt tolerance and little information is available on whether NPs application would mitigate the salt-induced effects. This study explored the influence of three oxide NPs and their application doses on improving salt tolerance in C. paliurus under simulated natural conditions. The results showed that these oxide NPs could modify the salt tolerance in C. paliurus seedlings, but the alleviating effects varied in the NPs types and their application doses. Under the salt stress, foliar applications of SiO2-NPs with 500 mg L−1 and MnO2-NPs with 50 mg L−1 significantly increased net photosynthetic rate and seedling height by 52.0–59.5 %, and reduced the salt injury index by 67.6–70.7 %. Transcriptomic analysis revealed that the genes related to photosynthesis pathway were well responsive to both salt stress and NPs application, while the applications of high-dose SiO2- and MnO2-NPs up-regulated the expression of 50 photosynthesis-related genes. Weighted gene co-expression network analysis (WGCNA) indicated there existed a close relationship between physiological parameters and gene expression patterns, and the nine key genes in mitigating salt stress in C. paliurus were identified after the NPs application. Our findings suggested that the effects of NPs on mitigating salt-induced damages depending on the NP type and applied dose. The applications of SiO2-NPs and MnO2-NPs with an appropriate dose hold great promise for mitigating the salt-induced photosynthetic dysfunction via regulation of related key genes, and ultimately promoting plant growth and ameliorating the salt-tolerance.

Comparative transcriptomic insights into key genes for biomass production and lipid synthesis in Chlorella sorokiniana mutated by argon and air atmospheric and room temperature plasma at different culture stages: Common mechanisms and unique differences

Metabolic mechanisms driving rapid lipid production in atmospheric and room temperature plasma-mutagenized Chlorella sorokiniana remain unclear, hindering improvement in lipid productivity through genetic modification. This study investigated two dominant strains, ArX13 and AirX12, mutated by argon and air ARTP, for growth, lipid production, and transcriptomic changes across various culture stages. Results showed that biomass and lipid contents peaked in the late stage, with ArX13 and AirX12 achieving final biomass of 0.71 g/L and 0.70 g/L, and lipid content of 58.57 % glipid gbiomass−1 and 46.90 % glipid gbiomass−1, 2.20 and 1.77 times higher than the control, respectively. The maximum biomass and lipid productivity occurred at the mid-stage, with ArX13 and AirX12 showing biomass productivity of 0.025 gbiomass L−1 day−1 and 0.024 gbiomass L−1 day−1, and lipid productivity of 17.79 mglipid L−1 day−1 and 11.40 mglipid L−1 day−1, respectively. Transcriptomic analysis revealed minimal changes of gene expression during early and late stages, but significant biomass and lipid synthesis during the middle stage. Key genes like PDHB, ATP6A, LSC1 and OGDH were identified in the PPI network throughout the culture cycle, with PDHB remarkably promoting lipid precursor production, up-regulated 8.37 and 4.99-fold in M_ArX13-M_X0 and M_AirX12-M_X0, respectively. In addition, high expression of photosynthesis-related genes (psaL, psaO, psaD, psaK, psbP) contributed the superior lipid production for the argon-based ARTP case, highlighting common and intrinsic mechanisms regulating microalgal lipid accumulation under different ARTP mutations. This study shows that the selection of appropriate ARTP gases can maximize the lipid production of microalgal, and the discovery of some key genes can provide a theoretical basis for the selection of target genes for microalgal research, which is of great significance for promoting the research and development of microalgal lipid engineering.

Toxicological effects, absorption and biodegradation of bisphenols with different functional groups in Chromochloris zofingiensis

Bisphenols (BPs) are recognized as endocrine disrupting compounds and have garnered increasing attention due to their widespread utilization. However, the varying biological toxicities and underlying mechanisms of BPs with different functional groups remain unknown. In the present study, the toxic effects of four BPs (BPA, BPS, BPAF, and TBBPA) on a photosynthetic microalgae Chromochloris zofingiensis were compared. Results showed that halogen-containing BPs exhibited higher cellular uptake, leading to more severe oxidative stress, lower photosynthetic efficiency, and greater accumulation of starch and lipids. Specifically, TBBPA with bromine groups showed a greater toxicity than BPAF with fluorine groups, possibly due to the incomplete debromination in C. zofingiensis. Transcriptomic analysis revealed that halogen-containing BPs triggered greater number of differentially expressed genes (DEGs), and only 64 common DEGs were found among different BPs, indicating that the effects of BPs with different functional groups varied greatly. Genes involved in endocytosis, peroxisomes, and endoplasmic reticulum protein processing pathways were mostly upregulated across different BPs, while photosynthesis-related genes showed varied expression, possibly due to their distinct functional groups. Additionally, SIN3A, ZFP36L, CHMP, and ATF2 emerged as potential key regulatory genes. Overall, this study thoroughly explained how functional groups impact the toxicity and biodegradation of BPs in C. zofingiensis.

Gene editing and overexpression of soybean miR396a reveals its role in salinity tolerance and development

MicroRNAs (miRNAs) are versatile regulators of gene expression at both the transcription and post-transcription levels. The microRNA miR396 plays vital roles in growth, development, and resistance to abiotic stresses in many plant species. However, the roles and functions of miR396 in soybeans are not well understood. Here, we report that Gm-miR396a influences soybean development and salinity tolerance. We found that soybean miR396a was responsive to salt stress. Gm-miR396a gene-edited lines (miR396a-GEs), created using CRISPR/Cas9, exhibited more branches, higher grain yields, and greater salinity tolerance than control plants. The transcripts in lines with altered abundance of miR396a-GE were significantly enriched for biological processes related to hormone regulation. Overexpression of the Gm-miR396a precursor (pre-miR396a-OE) resulted in developmental deficiencies including dwarfness, abnormal inflorescences and flowers, smaller and fewer seeds, and small leaves with larger and more numerous stomata. Transcriptome analysis indicated photosynthesis-related genes were downregulated in pre-miR396a-OE plants. These results contribute valuable insights into the function of Gm-miR396a in soybeans and hold promise for enhancing soybean yield and salinity tolerance through germplasm innovation.

Interference of skeleton photoperiod in circadian clock and photosynthetic efficiency of tea plant: in-depth analysis of mathematical model.

The circadian system of plants is a complex physiological mechanism, a biological process in which plants can adjust themselves according to the day and night cycle. To understand the effects of different photoperiods on the biological clock of tea plants, we analyzed the expression levels of core clock genes (CCA1, PRR9, TOC1, ELF4) and photosynthesis-related genes (Lhcb, RbcS, atpA) under normal light (light/dark = 12h/12h, 12L12D) and took the cost function defined by cycle and phase errors as the basic model parameter. In the continuous light environment (24h light, 24L), the peak activity and cycle of key genes that control the biological clock and photosynthesis were delayed by 1-2h. Under a skeleton photoperiod (6L6D, 3L3D), the expression profiles of clock genes and photosynthesis-related genes in tea plants were changed and stomatal opening showed a circadian rhythm. These observations suggest that a skeleton photoperiod may have an effect on the circadian rhythm, photosynthetic efficiency and stomatal regulation of tea plants. Our study and model analyzed the components of circadian rhythms under different photoperiodic pathways, and also revealed the underlying mechanisms of circadian regulation of photosynthesis in tea plants.

Cross-species transcriptomics reveals differential regulation of essential photosynthesis genes in Hirschfeldia incana.

Photosynthesis is the only yield-related trait not yet substantially improved by plant breeding. Previously, we have established H. incana as the model plant for high photosynthetic light-use efficiency (LUE). Now we aim to unravel the genetic basis of this trait in H. incana, potentially contributing to the improvement of photosynthetic LUE in other species. Here, we compare its transcriptomic response to high light with that of Arabidopsis thaliana, Brassica rapa, and Brassica nigra, 3 fellow Brassicaceae members with lower photosynthetic LUE. We built a high-light, high-uniformity growing environment, in which the plants developed normally without signs of stress. We compared gene expression in contrasting light conditions across species, utilizing a panproteome to identify orthologous proteins. In-depth analysis of 3 key photosynthetic pathways showed a general trend of lower gene expression under high-light conditions for all 4 species. However, several photosynthesis-related genes in H. incana break this trend. We observed cases of constitutive higher expression (like antenna protein LHCB8), treatment-dependent differential expression (as for PSBE), and cumulative higher expression through simultaneous expression of multiple gene copies (like LHCA6). Thus, H. incana shows differential regulation of essential photosynthesis genes, with the light-harvesting complex as the first point of deviation. The effect of these expression differences on protein abundance and turnover, and ultimately the high photosynthetic LUE phenotype is relevant for further investigation. Furthermore, this transcriptomic resource of plants fully grown under, rather than briefly exposed to, a very high irradiance, will support the development of highly efficient photosynthesis in crops.

Overexpression of MtIPT gene enhanced drought tolerance and delayed leaf senescence of creeping bentgrass (Agrostis stolonifera L.)

BackgroundIsopentenyltransferases (IPT) serve as crucial rate-limiting enzyme in cytokinin synthesis, playing a vital role in plant growth, development, and resistance to abiotic stress.ResultsCompared to the wild type, transgenic creeping bentgrass exhibited a slower growth rate, heightened drought tolerance, and improved shade tolerance attributed to delayed leaf senescence. Additionally, transgenic plants showed significant increases in antioxidant enzyme levels, chlorophyll content, and soluble sugars. Importantly, this study uncovered that overexpression of the MtIPT gene not only significantly enhanced cytokinin and auxin content but also influenced brassinosteroid level. RNA-seq analysis revealed that differentially expressed genes (DEGs) between transgenic and wild type plants were closely associated with plant hormone signal transduction, steroid biosynthesis, photosynthesis, flavonoid biosynthesis, carotenoid biosynthesis, anthocyanin biosynthesis, oxidation-reduction process, cytokinin metabolism, and wax biosynthesis. And numerous DEGs related to growth, development, and stress tolerance were identified, including cytokinin signal transduction genes (CRE1, B-ARR), antioxidase-related genes (APX2, PEX11, PER1), Photosynthesis-related genes (ATPF1A, PSBQ, PETF), flavonoid synthesis genes (F3H, C12RT1, DFR), wax synthesis gene (MAH1), senescence-associated gene (SAG20), among others.ConclusionThese findings suggest that the MtIPT gene acts as a negative regulator of plant growth and development, while also playing a crucial role in the plant’s response to abiotic stress.

Combined transcriptomics and metabolomics analysis reveals salinity stress specific signaling and tolerance responses in the seagrass Zostera japonica.

Multiple regulatory pathways of Zostera japonica to salt stress were identified through growth, physiological, transcriptomic and metabolomic analyses. Seagrasses are marine higher submerged plants that evolved from terrestrial monocotyledons and have fully adapted to the high saline seawater environment during the long evolutionary process. As one of the seagrasses growing in the intertidal zone, Zostera japonica not only has the ability to quickly adapt to short-term salt stress but can also survive at salinities ranging from the lower salinity of the Yellow River estuary to the higher salinity of the bay, making it a good natural model for studying the mechanism underlying the adaptation of plants to salt stress. In this work, we screened the growth, physiological, metabolomic, and transcriptomic changes of Z. japonica after a 5-day exposure to different salinities. We found that high salinity treatment impeded the growth of Z. japonica, hindered its photosynthesis, and elicited oxidative damage, while Z. japonica increased antioxidant enzyme activity. At the transcriptomic level, hypersaline stress greatly reduced the expression levels of photosynthesis-related genes while increasing the expression of genes associated with flavonoid biosynthesis. Meanwhile, the expression of candidate genes involved in ion transport and cell wall remodeling was dramatically changed under hypersaline stress. Moreover, transcription factors signaling pathways such as mitogen-activated protein kinase (MAPK) were also significantly influenced by salt stress. At the metabolomic level, Z. japonica displayed an accumulation of osmolytes and TCA mediators under hypersaline stress. In conclusion, our results revealed a complex regulatory mechanism in Z. japonica under salt stress, and the findings will provide important guidance for improving salt resistance in crops.

Exploring the Evolutionary History and Phylogenetic Relationships of Giant Reed (Arundo donax) through Comprehensive Analysis of Its Chloroplast Genome.

Giant reed (Arundo donax) is widely distributed across the globe and is considered an important energy crop. This study presents the first comprehensive analysis of the chloroplast genome of giant reed, revealing detailed characteristics of this species' chloroplast genome. The chloroplast genome has a total length of 137,153 bp, containing 84 protein-coding genes, 38 tRNA genes, and 8 rRNA genes, with a GC content of 39%. Functional analysis indicates that a total of 45 photosynthesis-related genes and 78 self-replication-related genes were identified, which may be closely associated with its adaptability and growth characteristics. Phylogenetic analysis confirmed that Arundo donax cv. Lvzhou No.1 belongs to the Arundionideae clade and occupies a distinct evolutionary position compared to other Arundo species. The findings of this study not only enhance our understanding of the giant reed genome but also provide valuable genetic resources for its application in biotechnology, bioenergy crop development, and ecological restoration.

Microplastics with different functional groups modulate cellular and molecular mechanisms of reduced graphene oxide toxicity on the green microalga, Scenedesmus obliquus

Even though microplastics (MPs) and graphene nanomaterials (GNMs) have demonstrated individual toxicity towards aquatic organisms, the knowledge gap lies in the lack of understanding regarding their combined toxicity. The difference between the combined toxicity of MPs and GNMs, in contrast to their individual toxicities, and furthermore, the elucidation of the mechanism of this combined toxicity are scientific questions that remain to be addressed. In this study, we examined the individual and combined toxicity of three polystyrene microplastics (MPs) with different functional groups—unmodified, carboxyl-modified (COOH-), and amino-modified (NH2-) MPs—in combination with reduced graphene oxide (RGO) on the freshwater microalga Scenedesmus obliquus. More importantly, we explored the cellular and molecular mechanisms responsible for the observed toxicity. The results indicated that the growth inhibition toxicity of RGO, either alone or in combination with the three MPs, against S. obliquus increased gradually with higher particle concentrations. The mitigating effect of MPs-NH2 on RGO-induced toxicity was most significant at a higher concentration, surpassing the effect of unmodified MPs. However, the MPs-COOH did not exhibit a substantial impact on the toxicity of RGO. Unmodified MPs and MPs-COOH aggravated the inhibition effects of RGO on the cell membrane integrity and oxidative stress-related biomarkers. Additionally, MPs-COOH exhibited a stronger inhibition effect on RGO-induced biomarkers compared to unmodified MPs. In contrast, the MPs-NH2 alleviated the inhibition effect of RGO on the biomarkers. Furthermore, the presence of differently functionalized MPs did not significantly affect RGO-induced oxidative stress and photosynthesis-related gene expression in S. obliquus, indicating a limited ability to modulate RGO genotoxicity at the molecular level. These findings can offer a more accurate understanding of the combined risks posed by these micro- and nano-materials and assist in designing more effective mitigation strategies.

Unmasking Spatial Heterogeneity in Phytotoxicology Mechanisms Induced by Carbamazepine by Mass Spectrometry Imaging and Multiomics Analyses.

Previous studies have highlighted the toxicity of pharmaceuticals and personal care products (PPCPs) in plants, yet understanding their spatial distribution within plant tissues and specific toxic effects remains limited. This study investigates the spatial-specific toxic effects of carbamazepine (CBZ), a prevalent PPCP, in plants. Utilizing desorption electrospray ionization mass spectrometry imaging (DESI-MSI), CBZ and its transformation products were observed predominantly at the leaf edges, with 2.3-fold higher concentrations than inner regions, which was confirmed by LC-MS. Transcriptomic and metabolic analyses revealed significant differences in gene expression and metabolite levels between the inner and outer leaf regions, emphasizing the spatial location's role in CBZ response. Notably, photosynthesis-related genes were markedly downregulated, and photosynthetic efficiency was reduced at leaf edges. Additionally, elevated oxidative stress at leaf edges was indicated by higher antioxidant enzyme activity, cell membrane impairment, and increased free fatty acids. Given the increased oxidative stress at the leaf margins, the study suggests using in situ Raman spectroscopy for early detection of CBZ-induced damage by monitoring reactive oxygen species levels. These findings provide crucial insights into the spatial toxicological mechanisms of CBZ in plants, forming a basis for future spatial toxicology research of PPCPs.

The HPE1 RNA-binding protein modulates chloroplast RNA editing to promote photosynthesis under cold stress in Arabidopsis.

Cold stress has severe negative consequences for plant growth and crop yield. Here, we report that an Arabidopsis thaliana mutant that lacks the HPE1 gene, which encodes an RNA-binding protein, maintains higher photosynthetic activity under cold stress, together with higher accumulation of thylakoid proteins. We showed that HPE1 interacts with MORF2 and MORF9 and thereby mediates RNA editing in chloroplasts. Loss of HPE1 function increased the editing efficiency at four RNA editing sites, rpoC-488, ndhB-149, ndhB-746 and matK-706, under cold stress and altered the expression of nuclear photosynthesis-related genes and cold-responsive genes. We propose that HPE1-mediated RNA editing acts as a trigger for retrograde signaling that affects photosynthesis under cold stress.