Photosynthesis-antenna Proteins Research Articles

Revealing the intricate temporal dynamics and adaptive responses of prokaryotic and eukaryotic microbes in the coastal South China Sea

This comprehensive two-year investigation in the coastal South China Sea has advanced our understanding of marine microbes at both community and genomic levels. By combining metagenomics and metatranscriptomics, we have revealed the intricate temporal dynamics and remarkable adaptability of microbial communities and phytoplankton metagenome-assembled genomes (MAGs) in response to environmental fluctuations. We observed distinct seasonal shifts in microbial community composition and function: cyanobacteria were predominant during warmer months, whereas photosynthetic protists were more abundant during colder seasons. Notably, metabolic marker KOs of photosynthesis were consistently active throughout the year, underscoring the persistent role of these processes irrespective of seasonal changes. Our analysis reveals that environmental parameters such as temperature, salinity, and nitrate concentrations profoundly influence microbial community composition, while temperature and silicate have emerged as crucial factors shaping their functional traits. Through the recovery and analysis of 37 phytoplankton MAGs, encompassing nine prokaryotic cyanobacteria and 28 eukaryotic protists from diverse phyla, we have gained insights into their genetic diversity and metabolic capabilities. Distinct profiles of photosynthesis-related pathways including carbon fixation, carotenoid biosynthesis, photosynthesis-antenna proteins, and photosynthesis among the MAGs indicated their genetic adaptations to changing environmental conditions. This study not only enhances our understanding of microbial dynamics in coastal marine ecosystems but also sheds light on the ecological roles and adaptive responses of different microbial groups to environmental changes.

Comparative transcriptome analysis and meta-QTLs mapping reveal the regulatory mechanism of cold tolerance in rice at the budding stage

Rice (Oryza sativa L.) is one of the most extensively farmed food crops, but its development and productivity are significantly impacted by cold stress during the budding period. In this study, transcriptome sequencing was conducted on two types of rice: the cold-sensitive indica rice A117 and the substantially cold-tolerant japonica rice B106 under control and cold treatments. Differentially expressed genes between the two materials under cold conditions were analyzed using GO and KEGG enrichment analyses. The results revealed that processes such as the TCA cycle, glycolysis/glycogenesis, oxidative phosphorylation, and glutathione metabolism contribute to B106's cold tolerance. Additionally, an enrichment analysis of cold-induced genes in each material and shared genes identified significant enrichment in pathways such as glutathione metabolism, phenylpropanoid biosynthesis, and photosynthesis-antenna proteins. Initial cold tolerance QTLs at the rice bud stage were collected from published literature, and meta-QTL mapping identified 9 MQTLs. Gene expression profiling led to the identification of 75 potential DEGs within the 9 MQTLs region, from which four candidate genes (Os02g0194100, Os03g0802500, Os05g0129000, and Os07g0462000) were selected using qRT-PCR and gene annotation. These findings provide genetic resources for further research on the molecular mechanisms underlying rice's response to cold stress during the bud stage.

Main metabolic pathways of Solanum nigrum L. hyperaccumulating cadmium except of copper simultaneously through differentially expressed proteins analysis

Determining the hyperaccumulation mechanism of Solanum nigrum L., which exclusively accumulates cadmium (Cd), presents significant challenges due to the difficulty in identifying its unique characteristics. While some metabolic pathways related to Cd accumulation can be explored, there are no methods to ascertain if other heavy metals may share the same pathways. Isobaric tags for relative and absolute quantitation (iTRAQ) were employed to investigate the metabolic pathways associated with Cd hyperaccumulation and Cu accumulation (non-Cu hyperaccumulator) by comparing differentially expressed proteins (DEPs). The results showed that 27 intersecting DEPs reflecting relative metabolic pathways related to Cd accumulation were identified by comparing DEPs in leaves and roots, including carbon metabolism, aminoacyl-tRNA biosynthesis, phagosome, peroxisome, as well as starch and sucrose metabolism. These pathways might be responsible for the values of Cd enrichment factor (EF) and translocation factor (TF) exceeding 1, associated with key proteins participated in phosphoenolpyruvate, carboxylase, chloroplastic catalytic activity, and granule-bound starch synthase I. The combined metabolic pathways identified by 2 intersecting DEPs related to Cu accumulation could result in Cu EF >1 in the 0.2 Cu mg kg−1 treatment, EF <1 in the 5 mg kg−1 treatment, and TF<1 in both treatments, associated with key proteins, which might concern photosynthesis-antenna proteins and hydroxymethylbilane synthase. No metabolic pathways related to simultaneous accumulation of Cd and Cu has been identified. The identified DEPs were validated using Western blotting with five key proteins. Additionally, Western blotting and yeast mutant confirmed the presence of proteins related to carbon fixation in photosynthetic organisms, carbon metabolism, peroxisome, as well as starch and sucrose metabolism. Photosynthetic, O2•−, H2O2 and non-enzymatic antioxidants indices reflecting protein-related differences indirectly supported the above results. These findings are crucial for further exploration of the Cd hyperaccumulation mechanism.

Comparative Metabolome and Transcriptome Analysis of Rapeseed (Brassica napus L.) Cotyledons in Response to Cold Stress.

Cold stress affects the seed germination and early growth of winter rapeseed, leading to yield losses. We employed transmission electron microscopy, physiological analyses, metabolome profiling, and transcriptome sequencing to understand the effect of cold stress (0 °C, LW) on the cotyledons of cold-tolerant (GX74) and -sensitive (XY15) rapeseeds. The mesophyll cells in cold-treated XY15 were severely damaged compared to slightly damaged cells in GX74. The fructose, glucose, malondialdehyde, and proline contents increased after cold stress in both genotypes; however, GX74 had significantly higher content than XY15. The pyruvic acid content increased after cold stress in GX74, but decreased in XY15. Metabolome analysis detected 590 compounds, of which 32 and 74 were differentially accumulated in GX74 (CK vs. cold stress) and XY15 (CK vs. cold stressed). Arachidonic acid and magnoflorine were the most up-accumulated metabolites in GX74 subjected to cold stress compared to CK. There were 461 and 1481 differentially expressed genes (DEGs) specific to XY15 and GX74 rapeseeds, respectively. Generally, the commonly expressed genes had higher expressions in GX74 compared to XY15 in CK and cold stress conditions. The expression changes in DEGs related to photosynthesis-antenna proteins, chlorophyll biosynthesis, and sugar biosynthesis-related pathways were consistent with the fructose and glucose levels in cotyledons. Compared to XY15, GX74 showed upregulation of a higher number of genes/transcripts related to arachidonic acid, pyruvic acid, arginine and proline biosynthesis, cell wall changes, reactive oxygen species scavenging, cold-responsive pathways, and phytohormone-related pathways. Taken together, our results provide a detailed overview of the cold stress responses in rapeseed cotyledons.

Ozone priming enhanced low temperature tolerance of wheat (Triticum aestivum L.) based on physiological, biochemical and transcriptional analyses.

Low temperature significantly inhibits the plant growth in wheat (Triticum aestivum L.), prompting the exploration of effective strategies to mitigate low temperature stress. Several priming methods enhance low temperature stress tolerant, however, the role of ozone priming remains unclear in wheat. Here we found ozone priming alleviated low temperature stress in wheat. Transcriptome analysis showed that ozone priming positively modulated 'photosynthesis-antenna proteins' pathway in wheat under low temperature. Which was confirmed by the results of the ozone-primed plants had higher trapped energy flux and electron transport flux per reaction, and less damage to chloroplasts than non-primed plants under low temperature. Ozone priming also mitigated the overstimulation of glutathione metabolism and induced the accumulation of total ascorbic acid and glutathione, maintained redox homeostasis in wheat under low temperature. Moreover, gene expressions and enzyme activities in glycolysis pathways were upregulated in ozone priming comparing with non-priming after the low temperature stress. Furthermore, exogenous antibiotics significantly increased low temperature tolerance, which further proved that the inhibition of ribosome biogenesis by ozone priming was involved in low temperature tolerance in wheat. In conclusion, ozone priming enhanced wheat low temperature tolerance through promoting light-harvesting capacity, redox homeostasis, and carbohydrate metabolism, as well as inhibiting ribosome biogenesis.

Comparative Transcriptome-Based Analysis of the Regulation of Leaf Senescence in the Upper and Middle Canopy of Different Soybean Cultivars

Premature leaf failure is one of the major factors contributing to crop yield reduction. High-yielding soybean cultivars exhibit a longer leaf lifespan during the reproductive period, promoting higher yields. In this experiment, physiological indexes and transcriptomics analysis were carried out on leaves of different canopy parts of two soybean cultivars with different senescence sensitivities of LD32 and SND28 as test materials. The results showed that the leaf senescence rates of the two soybean cultivars, tested at the grain-filling stage, were significantly different, and the senescence rates of the upper and middle canopy leaves of LD32 were significantly lower than those of SND28. In comparison to SND28, LD32 exhibited slower decreases in chlorophyll, net photosynthetic rate, and SPAD values in the upper and middle canopy leaves. The differentially expressed genes for senescence of upper and middle canopy leaves of both cultivars were enriched in four pathways: the photosynthesis pathway, the photosynthesis–antenna protein pathway, the MAPK signaling pathway–plant hormone signal transduction pathway, and the plant hormone signal transduction pathway. The differential expression of 20 genes (Ribose-5-phosphate isomerase, fructose-1,6-bisphosphatase, etc.) in the “carbon fixation in photosynthetic organisms” pathway of LD32 may be involved in the regulation of reducing the rate of leaf senescence in the middle of the canopy at the grain-filling stage of LD32. Ribose-5-phosphate isomerase and fructose-1,6-bisphosphatase in LD32 may reduce the rate of leaf senescence in the middle of the canopy during seed filling.

Abscisic acid enhances alkaline stress tolerance in grapevines: Physiological and transcriptional profiling

Abscisic acid (ABA) is a crucial signaling regulator governing plant growth and survival during adverse conditions. However, the mechanism by which ABA mediates grapevine tolerance to alkali stress has not yet been elucidated. Here, we investigated the role of ABA in regulating physiological characteristics and transcriptome of grapevines under alkali stress through the application of exogenous ABA and fluridone (an ABA biosynthesis inhibitor). The results revealed that alkali stress led to significant reductions in the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), chlorophyll content, the maximum quantum yields of primary photochemistry of PSII (Fv/Fm), nonphotochemical quenching (NPQ), which were greatly alleviated by exogenous ABA (50 and 100 μM) application. Specifically, the application of exogenous ABA (50 μM) increased Pn, chlorophyll content and Fv/Fm by 28.39 %, 30.45 % and 17.29 %, respectively, compared with alkali stress alone. Furthermore, exogenous ABA treatment reduced alkali stress-induced superoxide anions (O2∙−) and hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage, as well as higher proline content and activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). Additionally, exogenous ABA (50 μM) decreased O2∙−, H2O2, MDA, electrolyte leakage by 38.64 %, 28.16 %, 39.29 % and 39.42 %, respectively, respect to alkali stress alone. Moreover, exogenous ABA reduced the Na+, increased K+ and K+/Na+ ratio, as well as the phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI) activities and flavonoid content, and increased zeaxanthin epoxidase (ZEP) and 9-cis-epoxy carotenoid dioxygenase (NCED) activities and endogenous ABA levels in alkali stress-treated grapevines. Exogenous ABA (50 μM) increased flavonoid content and endogenous ABA content by 74.03 % and 20.84 %, compared with alkali stress alone, respectively. Conversely, exogenous fluridone exacerbated alkali stress-induced physiological damage in grapevine plants. Transcriptome analysis revealed that exogenous ABA (50 μM) and fluridone significantly induced the ‘Plant hormone signal transduction (ko04075)’, the ‘MAPK signaling pathway-plant (ko04016)’, ‘ABC transporters (ko02010)’, ‘Photosynthesis-antenna proteins (ko00196)’, ‘Flavonoid biosynthesis (ko00941)’, ‘Phenylpropanoid biosynthesis (ko00940)’ and other biological pathways and key gene involved in chlorophyll metabolism and ion transport. In conclusion, ABA markedly enhanced grapevines tolerance to alkali stress by modulating key biological pathways and physiological characteristics.

Chilling stress response in tobacco seedlings: insights from transcriptome, proteome, and phosphoproteome analyses.

Tobacco (Nicotiana tabacum L.) is an important industrial crop, which is sensitive to chilling stress. Tobacco seedlings that have been subjected to chilling stress readily flower early, which seriously affects the yield and quality of their leaves. Currently, there has been progress in elucidating the molecular mechanisms by which tobacco responds to chilling stress. However, little is known about the phosphorylation that is mediated by chilling. In this study, the transcriptome, proteome and phosphoproteome were analyzed to elucidate the mechanisms of the responses of tobacco shoot and root to chilling stress (4 °C for 24 h). A total of 6,113 differentially expressed genes (DEGs), 153 differentially expressed proteins (DEPs) and 345 differential phosphopeptides were identified in the shoot, and the corresponding numbers in the root were 6,394, 212 and 404, respectively. This study showed that the tobacco seedlings to 24 h of chilling stress primarily responded to this phenomenon by altering their levels of phosphopeptide abundance. Kyoto Encyclopedia of Genes and Genomes analyses revealed that starch and sucrose metabolism and endocytosis were the common pathways in the shoot and root at these levels. In addition, the differential phosphopeptide corresponding proteins were also significantly enriched in the pathways of photosynthesis-antenna proteins and carbon fixation in photosynthetic organisms in the shoot and arginine and proline metabolism, peroxisome and RNA transport in the root. These results suggest that phosphoproteins in these pathways play important roles in the response to chilling stress. Moreover, kinases and transcription factors (TFs) that respond to chilling at the levels of phosphorylation are also crucial for resistance to chilling in tobacco seedlings. The phosphorylation or dephosphorylation of kinases, such as CDPKs and RLKs; and TFs, including VIP1-like, ABI5-like protein 2, TCP7-like, WRKY 6-like, MYC2-like and CAMTA7 among others, may play essential roles in the transduction of tobacco chilling signal and the transcriptional regulation of the genes that respond to chilling stress. Taken together, these findings provide new insights into the molecular mechanisms and regulatory networks of the responses of tobacco to chilling stress.

GWAS and WGCNA Analysis Uncover Candidate Genes Associated with Oil Content in Soybean.

Soybean vegetable oil is an important source of the human diet. However, the analysis of the genetic mechanism leading to changes in soybean oil content is still incomplete. In this study, a total of 227 soybean materials were applied and analyzed by a genome-wide association study (GWAS). There are 44 quantitative trait nucleotides (QTNs) that were identified as associated with oil content. A total of six, four, and 34 significant QTN loci were identified in Xiangyang, Hulan, and Acheng, respectively. Of those, 26 QTNs overlapped with or were near the known oil content quantitative trait locus (QTL), and 18 new QTNs related to oil content were identified. A total of 594 genes were located near the peak single nucleotide polymorphism (SNP) from three tested environments. These candidate genes exhibited significant enrichment in tropane, piperidine, and pyridine alkaloid biosynthesiss (ko00960), ABC transporters (ko02010), photosynthesis-antenna proteins (ko00196), and betalain biosynthesis (ko00965). Combined with the GWAS and weighted gene co-expression network analysis (WGCNA), four candidate genes (Glyma.18G300100, Glyma.11G221100, Glyma.13G343300, and Glyma.02G166100) that may regulate oil content were identified. In addition, Glyma.18G300100 was divided into two main haplotypes in the studied accessions. The oil content of haplotype 1 is significantly lower than that of haplotype 2. Our research findings provide a theoretical basis for improving the regulatory mechanism of soybean oil content.

Effect of cold stress on photosynthetic physiological characteristics and molecular mechanism analysis in cold-resistant cotton (ZM36) seedlings.

Low temperature and cold damage seriously hinder the growth, development, and morphogenesis of cotton seedlings. However, the response mechanism of cotton seedlings under cold stress still lacks research. In this study, transcriptome sequencing, gas exchange parameters, and rapid chlorophyll fluorescence parameters were analyzed in leaves of cold-tolerant upland cotton variety "ZM36" under different temperature stress [25°C (T25, CK), 15°C (T15), 10°C (T10), and 4°C (T4)]. The results showed that the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), PSII potential maximum photochemical efficiency (Fv/Fm), and performance index (PIabs) of cotton leaves significantly decreased, and the intercellular CO2 concentration (Ci) and Fo/Fm significantly increased under cold stress. The transcriptome sequencing analysis showed that a total of 13,183 DEGs were involved in the response of cotton seedlings at each temperature point (T25, T15, T10, and T4), mainly involving five metabolic pathways-the phosphatidylinositol signaling system, photosynthesis, photosynthesis antenna protein, carbon fixation in photosynthetic organisms, and carotenoid synthesis. The 1,119 transcription factors were discovered among all the DEGs. These transcription factors involve 59 families, of which 15.8% of genes in the NAC family are upregulated. Through network regulatory analysis, the five candidate genes GhUVR8 (GH_A05G3668), GhPLATZ (GH_A09G2161), GhFAD4-1 (GH_A01G0758), GhNFYA1 (GH_A02G1336), and GhFAD4-2 (GH_D01G0766) were identified in response to cold stress. Furthermore, suppressing the expression level of GhPLATZ by virus-induced gene silencing led to the reduction of low temperature resistance, implying GhPLATZ as a positive regulator of low temperature tolerance. The findings of the study revealed a piece of the complex response mechanism of the cold-tolerant variety "ZM36" to different cold stresses and excavated key candidate genes for low temperature response, which provided support for accelerating the selection and breeding of cotton varieties with low temperature tolerance.

Comprehensive physiology and proteomics analysis revealed the resistance mechanism of rice (Oryza sativa L) to cadmium stress

Cadmium contamination can lead to a decrease in crop yield and quality. However, Cd-tolerant rice can improve rice resistance genes, improve crop tolerance to heavy metals, and protect plants from oxidative damage. In this study, Japonica rice: Chunyou 987 and Indica rice: Chuanzhong you 3607 were used to reveal the molecular response mechanism of Cd-tolerant rice under cadmium concentration of 3 mg/kg through comparative experiments combined with physiology and proteomics. The results showed that compared with indica rice, japonica rice showed more robust resistance to Cd stress and effectively retained many Cd ions in roots. Moreover, it enhanced its enzymatic and non-enzymatic anti-oxidative stress mechanism, which increased the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) by 47.37%, 21.75%, and 55.42%, respectively. The contents of non-enzymatic antioxidant substances ascorbic acid (AsA), glutathione (GSH), cysteine (Cys), proline (PRO), anthocyanins (OPC), and flavonoids were increased by 25.32%, 42.67%, 21.43%, 50.81%, 33.23%, and 72.16%, respectively. Through proteomics analysis, it was found that in response to the damage caused by cadmium stress, Japonica rice makes Photosynthesis functional proteins (psbO and PetH), Photosynthesis antenna proteins (LHCA and ASCAB9), Carbon fixation functional proteins (PEPC and OsAld), Porphyrin metabolism functional proteins (OsRCCR1 and SE5), Glyoxylate and dicarboxylate The expression of metabolism functional proteins (CATC and GLO4.) and Glutathione metabolism functional proteins (APX8 and OsGSTU13) were significantly up-regulated, which stimulated the antioxidant stress mechanism and photosynthetic system, and constructed a robust energy supply system to ensure the normal metabolic activities of life. Strengthening the mechanisms of plant homeostasis. In summary, this study revealed the molecular mechanism of tolerance to Cd stress in japonica rice, and the results of this study will provide a possible way to improve Cd-resistant rice seedlings.

Shading Treatment Reduces Grape Sugar Content by Suppressing Photosynthesis-Antenna Protein Pathway Gene Expression in Grape Berries.

To explore the impact of shade treatment on grape berries, 'Marselan' grape berries were bagged under different light transmission rates (100% (CK), 75% (A), 50% (B), 25% (C), 0% (D)). It was observed that this treatment delayed the ripening of the grape berries. The individual weight of the grape berries, as well as the content of fructose, glucose, soluble sugars, and organic acids in the berries, was measured at 90, 100, and 125 days after flowering (DAF90, DAF100, DAF125). The results revealed that shading treatment reduced the sugar content in grape berries; the levels of fructose and glucose were higher in the CK treatment compared to the other treatments, and they increased with the duration of the shading treatment. Conversely, the sucrose content exhibited the opposite trend. Additionally, as the weight of the grape berries increased, the content of soluble solids and soluble sugars in the berries also increased, while the titratable acidity decreased. Furthermore, 16 differentially expressed genes (DEGs) were identified in the photosynthesis-antenna protein pathway from the transcriptome sequencing data. Correlation analysis revealed that the expression levels of genes VIT_08s0007g02190 (Lhcb4) and VIT_15s0024g00040 (Lhca3) were positively correlated with sugar content in the berries at DAF100, but negatively correlated at DAF125. qRT-PCR results confirmed the correlation analysis. This indicates that shading grape clusters inhibits the expression of genes in the photosynthesis-antenna protein pathway in the grape berries, leading to a decrease in sugar content. This finding contributes to a deeper understanding of the impact mechanisms of grape cluster shading on berry quality, providing important scientific grounds for improving grape berry quality.

Transcriptomic profiling reveals the contribution of Nitric Oxide to maintaining photosynthesis and antioxidant ability in Hylotelephium erythrostictum leaves under salt stress

Hylotelephium erythrostictum is a plant species with high garden value and notable salt tolerance, yet the salt tolerance mechanism is poorly understood. In this study, we treated the plants under salt stress with exogenous nitric oxide (NO) and discovered that the content of malondialdehyde (MDA) decreased, while soluble sugar increased. The chlorophyll fluorescence parameters, such as the maximum photochemical efficiency of PS II (Fv/Fm), actual quantum yield Y(II), and the photochemical quenching coefficient (qP) increased, whereas the non-photochemical quenching coefficient (NPQ) decreased. Afterthat, we performed transcriptome sequencing on leaves treated with 200 mM NaCl after 0, 5, and 10 d. A total of 124,008 unigenes were identified and functionally annotated. Transcripts related to NO synthase exhibited increased expression levels, and transcripts related to superoxide dismutase (SOD) and catalase (CAT) were also significantly upregulated. In contrast, the majority of the differently expressed genes (DEGs) associated with photosynthesis and photosynthesis-antenna protein metabolic pathways were downregulated. Furthermore, the expression levels of HeSOD2, HeCAT2, HeCab1, and HepsaA were significantly upregulated. These results suggest that NO enhances the photosynthetic and antioxidant capacity of H. erythrostictum and improves salt tolerance. Our study will lead to a better understanding of how this plant responds to stressful conditions and potentially develop ways to enhance its salt tolerance by identifying salt-tolerance genes.

Comprehensive physiology and proteomics analysis revealed the molecular toxicological mechanism of Se stress on indica and japonica rice

Selenium pollution can lead to a decrease in crop yield and quality. However, the toxicological mechanisms of high Se concentrations on crops remain unclear. This study aimed to elucidate the physiological and proteomic molecular responses to Se stress in Oryza sativa. The results showed that under selenium stress, enzymatic activities of catalase, peroxidase, and superoxide dismutase in indica rice decreased by 61%, 28%, and 68%, respectively. The contents of non-enzymatic antioxidant substances ascorbic acid, glutathione, cysteine, proline, anthocyanidin, and flavonoids were decreased by 13%, 39%, 46%, 32%, 20%, and 5%, respectively, which significantly inhibited the antioxidant stress process of plants. At the same time, the results of proteomics analysis showed that rice seedlings, under Se stress, are involved in photosynthesis, photosynthesis-antenna proteins, carbon fixation, porphyrin metabolism, glyoxylate, and dicarboxylate. The differentially expressed proteins in metabolism and glutathione metabolism pathways showed a downward trend. It significantly inhibited the anti-oxidative stress, photosynthesis, and energy cycling process in plant cells, destroyed the homeostasis balance of rice plants, and inhibited the growth and development of rice. This finding reveals the molecular toxicological mechanism of Se stress on rice seedlings and provides a possible way to improve Se-resistant rice seedlings.

Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in "Jin Hong" branches.

Valsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear. In this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the 'Jin Hong' apple branches to the invasion of C. mali. Results showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.

Barley yellow dwarf virus-GAV 17K protein disrupts thiamine biosynthesis to facilitate viral infection in plants.

Thiamine functions as a crucial activator modulating plant health and broad-spectrum stress tolerances. However, the role of thiamine in regulating plant virus infection is largely unknown. Here, we report that the multifunctional 17K protein encoded by barley yellow dwarf virus-GAV (BYDV-GAV) interacted with barley pyrimidine synthase (HvTHIC), a key enzyme in thiamine biosynthesis. HvTHIC was found to be localized in chloroplast via an N-terminal 74-amino acid domain. However, the 17K-HvTHIC interaction restricted HvTHIC targeting to chloroplasts and triggered autophagy-mediated HvTHIC degradation. Upon BYDV-GAV infection, the expression of the HvTHIC gene was significantly induced, and this was accompanied by accumulation of thiamine and salicylic acid. Silencing of HvTHIC expression promoted BYDV-GAV accumulation. Transcriptomic analysis of HvTHIC silenced and non-silenced barley plants showed that the differentially expressed genes were mainly involved in plant-pathogen interaction, plant hormone signal induction, phenylpropanoid biosynthesis, starch and sucrose metabolism, photosynthesis-antenna protein, and MAPK signaling pathway. Thiamine treatment enhanced barley resistance to BYDV-GAV. Taken together, our findings reveal a molecular mechanism underlying how BYDV impedes thiamine biosynthesis to uphold viral infection in plants.

Effects of different light intensity on leaf color changes in a Chinese cabbage yellow cotyledon mutant.

Leaf color is one of the most important phenotypic features in horticultural crops and directly related to the contents of photosynthetic pigments. Most leaf color mutants are determined by the altered chlorophyll or carotenoid, which can be affected by light quality and intensity. Our previous study obtained a Chinese cabbage yellow cotyledon mutant that exhibited obvious yellow phenotypes in the cotyledons and the new leaves. However, the underlying mechanisms in the formation of yellow cotyledons and leaves remain unclear. In this study, the Chinese cabbage yellow cotyledon mutant 19YC-2 exhibited obvious difference in leaf color and abnormal chloroplast ultrastructure compared to the normal green cotyledon line 19GC-2. Remarkably, low-intensity light treatment caused turn-green leaves and a significant decrease in carotenoid content in 19YC-2. RNA-seq analysis revealed that the pathways of photosynthesis antenna proteins and carotenoid biosynthesis were significantly enriched during the process of leaf color changes, and many differentially expressed genes related to the two pathways were identified to respond to different light intensities. Remarkably, BrPDS and BrLCYE genes related to carotenoid biosynthesis showed significantly higher expression in 19YC-2 than that in 19GC-2, which was positively related to the higher carotenoid content in 19YC-2. In addition, several differentially expressed transcription factors were also identified and highly correlated to the changes in carotenoid content, suggesting that they may participate in the regulatory pathway of carotenoid biosynthesis. These findings provide insights into the molecular mechanisms of leaf color changes in yellow cotyledon mutant 19YC-2 of Chinese cabbage.

Molecular mechanism of dissolvable metal nanoparticles-enhanced CO2 fixation by algae: Metal-chlorophyll synthesis

Algae-driven photosynthetic CO2 fixation is a promising strategy to mitigate global climate changes and energy crises. Yet, the presence of metal nanoparticles (NPs), particularly dissolvable NPs, in aquatic ecosystems introduces new complexities due to their tendency to release metal ions that may perturb metabolic processes related to algal CO2 fixation. This study selected six representative metal NPs (Fe3O4, ZnO, CuO, NiO, MgO, and Ag) to investigate their impacts on CO2 fixation by algae (Chlorella vulgaris). We discovered an intriguing phenomenon that bivalent metal ions released from the metal NPs, especially from ZnO NPs, substituted Mg2+ within the porphyrin ring. This interaction led to 81.8% and 76.1% increases in Zinc-chlorophyll and Magnesium-chlorophyll contents within algal cells at 0.01 mM ZnO NPs, respectively. Integrating metabolomics and transcriptomics analyses revealed that ZnO NPs mainly promoted the photosynthesis-antenna protein pathway, porphyrin and chlorophyll metabolism, and carbon fixation pathway, thereby mitigating the adverse effects of Zn2+ substitution in light harvesting and energy transfer for CO2 fixation. Ultimately, the genes encoding Rubisco large subunit (rbcL) responsible for CO2 fixation were upregulated to 2.60-fold, resulting in a 76.3% increase in carbon fixation capacity. Similar upregulations of rbcL expression (1.13-fold) and carbon fixation capacity (76.1%) were observed in algal cells even at 0.001 mM ZnO NPs, accompanied by valuable lipid accumulation. This study offers novel insights into the molecular mechanism underlying NPs on CO2 fixation by algae and potentially introduces strategies for global carbon sequestration.

Photoheterotroph improved the growth and nutrient levels of Chlorella vulgaris and the related molecular mechanism

Microalgae are rich in fatty acids, proteins, and other nutrients, which have gained the general attention of researchers all over the world. For the development of Chlorella vulgaris in food and feed industry, this study was conducted to investigate the differences in C. vulgaris’ growth and nutritional components under different culture conditions (autotrophic, heterotrophic, photoheterotrophic) and the internal factors through cell counting in combination with transcriptome and nutrient analyses. The results showed that, under the photoheterotrophic condition, Chlorella’s growth and the contents of lipid and protein were significantly higher than that under the heterotrophic condition, and the moisture content was lower than that under the heterotrophic condition. The saturated fatty acid content under the photoheterotrophic condition was the lowest, while the polyunsaturated fatty acid content was significantly higher than those under the other two conditions. There were 46,583 differentially expressed genes (DEGs), including 33,039 up-regulated DEGs (70.93%) and 13,544 down-regulated DEGs (29.07%), under the photoheterotrophic condition in comparison with the autotrophic condition. The fold change between the two conditions of samples of up-regulated genes was higher than that of the down-regulated genes. The KEGG enrichment showed that the up-regulated DEGs in the photoheterotrophic condition were significantly enriched in 5 pathways, including protein processing in endoplasmic reticulum pathway, photosynthesis pathway, photosynthesis-antenna protein pathway, endocytosis pathway, and phosphonate and phosphinate metabolism pathway. DEGs related to fatty acid metabolic pathways were significantly enriched in the fatty acid biosynthesis pathway and the biosynthesis of unsaturated fatty acid pathway. The qPCR analysis showed that the expression pattern of the selected genes was consistent with that of transcriptome analysis. The results of this study lay a theoretical foundation for the large-scale production of Chlorella and its application in food, feed, and biodiesel.Key points• Nutrient levels under photoheterotrophic condition were higher than other conditions.• Six important pathways were discovered that affect changes in nutritional composition.• Explored genes encode important enzymes in the differential metabolic pathways.

Glyphosate hormesis stimulates tomato (Solanum lycopersicum L.) plant growth and enhances tolerance against environmental abiotic stress by triggering nonphotochemical quenching.

Glyphosate is the most widely applied herbicide in the world. Hormesis caused by low glyphosate doses has been widely documented in many plant species. However, the specific adaptative mechanism of plants responding to glyphosate hormesis stimulation remains unclear. This study focused on the biphasic relationship between glyphosate dose and tomato plant growth, and how glyphosate hormesis stimulates plant growth and enhances tolerance to environmental stress. We constructed a hormesis model to describe the biphasic relationship with a maximal stimulation (MAX) of 162% above control by glyphosate at 0.063 g ha-1. Low-dose glyphosate increased photosynthetic pigment contents and improve photosynthetic efficiency, leading to plant growth stimulation. We also found that glyphosate hormesis enhanced plant tolerance to diuron (DCMU; a representative photosynthesis inhibitor) by triggering the nonphotochemical chlorophyll fluorescence quenching (NPQ) reaction to dissipate excess energy stress from photosystem II (PSII). Transcriptomic analysis and quantitative real-time polymerase chain reaction results revealed that the photosynthesis-antenna proteins pathway was the most sensitive to glyphosate hormesis, and PsbS (encoding photosystem II subunit S), ZEP (encoding zeaxanthin epoxidase) and VDE (encoding violaxanthin de-epoxidase) involved in NPQ played crucial roles in the plant response to glyphosate hormesis. These results provide novel insights into the mechanisms of plant hormesis and is meaningful to the application of glyphosate hormesis in agriculture. © 2024 Society of Chemical Industry.