Search Results (51)

We present two complementary approaches to the Gorini–Kossakowski–Sudarshan–Lindblad equation for an open qubit. First, based on linearity, yields solutions illustrated by mixed-state trajectories in the Bloch ball, including non-random asymptotic fixed points and exceptional points. Second, exploiting the SU$\left(2\right)$ symmetry, leads to a nonlinear dynamical system that separates angular dynamics from radial dissipation. This symmetry-based perspective presents a promising route toward generalization to open qudits. Full article

Background. The genus Streptomyces is known for its capability to produce a wide range of bioactive secondary metabolites. The enzymes required for their synthesis are encoded within biosynthetic gene clusters (BGCs), whose expression can be influenced by various physical and nutritional factors. Among these nutritional factors, it is worth highlighting carbon catabolic repression (CCR), which prevents the formation of secondary metabolites. It has been shown that transcriptional factors, in turn, regulated by glucose or by the enzyme glucose kinase (Glk), may be involved in this mechanism. It was shown that the expression of some transcriptional factors is regulated by glucose availability and that the enzyme glucose kinase (Glk) may play a role in this process. One of the transcriptional factors most upregulated in the presence of glucose/agar in Streptomyces coelicolor M145 is SCO7424, a member of the MarR family of transcriptional regulators. However, its influence on antibiotic synthesis has never been studied. Objective. In this work, we evaluated the effect of SCO7424 overexpression on the synthesis of actinorhodin (ACT) and undecylprodigiosin (RED), and its impact on growth and glucose consumption. Methods. A copy of the sco7424 gene was cloned into the pIJ702 plasmid, which was then transformed into a wild-type strain of S. coelicolor M145. Growth and antibiotic production were evaluated in the strain with two copies of sco7424 and in the wild-type strain. We also evaluated the expression of the probable target genes by quantitative RT-PCR. Results. We found that overexpression of sco7424 negatively impacts growth, glucose consumption kinetics, and the expression of specific regulators of the ACT and RED biosynthetic pathways, resulting in reduced ACT and RED production. Understanding the function of the regulatory cascades regulated by this family of regulators is crucial for boosting the yields of valuable metabolites produced by industrial strains. Full article

Leaf color mutants are valuable resources for studying photosynthesis, pigment metabolism, and gene regulatory networks in plants. In this study, a naturally occurring sweetpotato albino mutant exhibiting a stable white-leaf phenotype across developmental stages was identified and compared with its green-leaf wild type to elucidate the molecular mechanisms underlying albinism. The mutant showed a dramatic 98.8% reduction in total chlorophyll content and a markedly decreased Fv/Fm value (0.59), indicating severe impairment of PSII efficiency. Integrated transcriptomic analysis identified 3520 differentially expressed genes (DEGs), while metabolomic profiling revealed 270 differentially accumulated metabolites (DAMs). Genes involved in chlorophyll and carotenoid biosynthesis, chloroplast development, and photosynthetic electron transport were strongly repressed, including key regulators such as GLK1, PORA, and PORB. Metabolomic alterations were mainly enriched in flavonoids, phenylpropanoids, and amino acid-derived pathways, reflecting broad reprogramming of both primary and secondary metabolism. These changes were accompanied by severely disrupted chloroplast ultrastructure, suggesting a primary defect in plastid development. Collectively, the integrated multi-omics evidence provides a comprehensive understanding of the coordinated transcriptional and metabolic alterations driving the albino phenotype in sweetpotato and establishes this mutant as a potential model for studying the interplay between chloroplast biogenesis, photosynthesis, and secondary metabolism. Full article

Phosphorus (P) deficiency is a critical constraint to cultivated potato (Solanum tuberosum L.) production, while wild potato germplasm is known to harbor traits that enhance tolerance to low P conditions. The aim of this study was to evaluate the tolerance to P deficiency in cultivated and wild potato accessions from a genebank to identify interesting germplasm for potato breeding. Therefore, ten wild potato accessions and 30 cultivated varieties were evaluated under high (15 mg L⁻¹) and low (3 mg L⁻¹) P regimes for various morphological, physiological, and nutrient uptake traits. Significant genotypic variation was observed across all traits, with notable interspecific differences. While low P generally reduced biomass, several genotypes, particularly S. stenotomum accessions, showed enhanced root growth and greater root length per unit shoot biomass. Wild accessions (GLKS 38153, GLKS 38159, GLKS 38161, and GLKS 38163; S. chacoense), maintained biomass through efficient internal P use, whereas others displayed high P uptake with limited growth conversion. GLKS 38159 demonstrated remarkable P efficiency, achieving high biomass with lower P uptake. Cultivated varieties, including Ikar, Tiger, Tarzan, Borka, and Fransen, displayed diverse adaptive strategies, including longer roots and sustained biomass. These findings underscore the resilience of wild potatoes to nutrient stress and provide valuable insights for breeders targeting improved P use efficiency in potato varieties. Full article

GOLDEN2-LIKEs (GLKs) are important transcription factors for the chloroplast development influencing photosynthesis, nutrition, senescence, and stress response in plants. Sunflower (Helianthus annuus) is a highly photosynthetic plant; here, a GLK-homologues gene HaGLK was identified from the sunflower genome by bioinformatics. To analyze the bio-function of HaGLK, transgenic rice plants overexpressing HaGLK (HaGLK-OE) were constructed and characterized via phenotype. Compared to the wild-type control rice variety Zhonghua 11 (ZH11), the HaGLK-OE lines exhibited increased photosynthetic pigment contents, higher net photosynthetic rates, and enlarged chloroplast area; meanwhile, genes involved in both photosynthesis and chlorophyll biosynthesis were also significantly up-regulated. Significantly, the HaGLK-OE plants showed a 12–13% increase in yield per plant. Additionally, the HaGLK-OE plants were demonstrated to have improved salt and drought tolerance compared to the control ZH11. Our results indicated that the HaGLK gene could play multiple roles in photosynthesis and stress response in rice, underscoring its potential value for improving crop productivity and environmental adaptability in breeding. Full article

The main objective of this study was to reveal the molecular mechanism of the albinism in Schima superba and to identify the related functional genes to provide theoretical support for the optimization of S. superba seedling nursery technology. Combining third-generation SMRT sequencing with second-generation high-throughput sequencing technology, the transcriptomes of normal seedlings and albinism seedlings of S. superba were analyzed and the sequencing data were functionally annotated and deeply resolved. The results showed that 270 differentially expressed transcripts were screened by analyzing second-generation sequencing data. KEGG enrichment analysis of the annotation information revealed that, among the photosynthesis-antenna protein-related pathways, the expression of LHCA3 and LHCB6 was found to be down-regulated in S. superba albinism seedlings, suggesting that the down-regulation of photosynthesis-related proteins may affect the development of chloroplasts in leaves. Down-regulated expression of VDE in the carotenoid biosynthesis leads to impaired chlorophyll cycling. In addition, transcription factors (TFs), such as bHLH, MYB, GLK and NAC, were closely associated with chloroplast development in S. superba seedlings. In summary, the present study systematically explored the transcriptomic features of S. superba albinism seedlings, screened out key genes with significant differential expression and provide a reference for further localization and cloning of the key genes for S. superba albinism, in addition to laying an essential theoretical foundation for an in-depth understanding of the molecular mechanism of the S. superba albinism. The genes identified in this study that are associated with S. superba albinism will be important targets for genetic modification or molecular marker development, which is essential for improving the cultivation efficiency of S. superba. Full article

As a widely cultivated warm-season turfgrass, bermudagrass (Cynodon spp.) faces significant challenges in shaded environments due to its inherent low-light sensitivity. While improving photosynthetic adaptation represents a promising strategy to address this limitation, the associated regulatory mechanisms remain insufficiently characterized. In this study, we found that the overexpression of CdGLK1 significantly improved low-light tolerance in bermudagrass by increasing shoot weight, root weight, chlorophyll a, chlorophyll b, net photosynthetic rate (Pn), and maximum quantum yield of photosystem II (Fv/Fm). Furthermore, coordinated upregulation of both C₃ and C₄ pathway enzymes was observed under low-light stress, accompanied by enhanced antioxidant capacity and reduced photoxidative damage. Transcriptomic profiling further revealed CdGLK1-mediated activation of photosynthetic machinery components spanning light harvesting, electron transport, and carbon fixation modules. These findings establish CdGLK1 as a master integrator of photoprotection and metabolic adaptation under light-limiting conditions, providing both mechanistic insights and practical strategies for developing shade-resilient turfgrass cultivars. Full article

The mechanisms underlying leaf variegation in the ornamental Ilex × ‘Solar Flare’ remain poorly understood. To investigate this phenomenon, we conducted a comprehensive characterization of its variegated leaves. Compared to green sectors, yellow sectors exhibited severe chloroplast structural abnormalities, including swollen chloroplasts, damaged thylakoid membranes, and reduced chloroplast numbers. These yellow sectors also showed significantly lower chlorophyll and carotenoid levels, along with a depletion of key chlorophyll precursors—protoporphyrin IX (Proto IX), magnesium protoporphyrin IX (Mg-Proto IX), and protochlorophyllide (Pchlide). Photosynthetic efficiency was significantly impaired. Comparative transcriptome analysis identified 3510 differentially expressed genes (DEGs) between yellow and green sectors. Key disruptions in chlorophyll biosynthesis included upregulated CHLD expression and downregulated CHLH and CHLG expression, leading to impaired chlorophyll synthesis. Additionally, chlorophyll degradation was accelerated by PAO upregulation. Defective chloroplast development in yellow sectors was associated with the downregulation of GLK1, GLK2, and thylakoid membrane-related genes (PsbC, PsbO, PsbR, PsaD, and PsaH). These molecular alterations likely drive the variegated phenotype of I. × ‘Solar Flare’. These observations advance our understanding of the genetic and physiological mechanisms regulating leaf variegation in this cultivar. Full article

Chloroplast biogenesis and development are essential processes in plants, profoundly influencing their growth, survival, and productivity. However, the transcription factors controlling chloroplast development, especially in roots, are poorly characterized. Here, we demonstrate that the ectopic expression of the seed-specific transcription factor Plant Growth Regulator 37 (PGA37) promotes chloroplast development in roots, causing root-greening. Using a steroid-inducible gene expression system and RNA-Seq, we identified 97 potential PGA37 target genes. Notably, PGA37 directly activates the transcription factor GOLDEN2-LIKE (GLK2), which governs chloroplast biogenesis. An overexpression of GLK2 replicated the root-greening phenotype observed in PGA37-overexpressing plants, while GLK2 mutation significantly reduced chlorophyll content and suppressed root-greening in PGA37-overexpressing seedlings. Furthermore, PGA37 directly binds to the promoters of type-B response regulators ARR13 and ARR21, thereby activating the cytokinin signaling pathway. Mutations in these regulators partially diminished chlorophyll accumulation in PGA37-overexpressing seedlings, suggesting that PGA37-regulated chloroplast development is partially mediated by the cytokinin signaling through ARR13 and ARR21. Taken together, we propose that PGA37 orchestrates chloroplast development by coordinately regulating transcription factors from various families, including GLK2, ARR13, and ARR21, positioning it as a key regulator of chloroplast development. Full article

Background/Objectives: The GARP transcription factor superfamily is crucial for plant growth, development, and stress responses. This study systematically identified and analyzed the GARP family genes in Populus deltoides to explore their roles in plant development and abiotic stress responses. Methods: A total of 58 PdGARP genes were identified using bioinformatics tools. Their physicochemical properties, genomic locations, conserved motifs, gene structures, and phylogenetic relationships were analyzed. Expression patterns under phosphorus and nitrogen deficiency, as well as tissue-specific expression, were investigated using RT-qPCR. Transgenic RNAi lines were generated to validate the function of GLK genes in chlorophyll biosynthesis. Results: The 58 PdGARP genes were classified into five subfamilies based on their evolutionary relationships and protein sequence similarity. Segmental duplication was found to be the primary driver of the PdGARP family’s expansion. Cis-regulatory elements (CREs) related to light, hormones, and abiotic stresses were identified in the promoters of PdGARP genes. Differential expression patterns were observed for NIGT1/HRS1/HHO and PHR/PHL subfamily members under phosphorus and nitrogen deficiency, indicating their involvement in stress responses. KAN subfamily members exhibited tissue-specific expression, particularly in leaves. Structural analysis of the GLK subfamily revealed conserved α-helices, extended chains, and irregular coils. Transgenic RNAi lines targeting GLK genes showed significant reductions in chlorophyll and carotenoid content. Conclusions: This study provides a comprehensive analysis of the GARP transcription factor superfamily in P. deltoides, highlighting their potential roles in nutrient signaling and stress response pathways. The findings lay the foundation for further functional studies of PdGARP genes and their application in stress-resistant breeding of poplar. Full article

GOLDEN2-LIKE (GLK) transcription factors are crucial regulators of chloroplast development and stress responses in plants. In this study, we investigated the GLK gene family in Phoebe bournei (Hemsl.) Yen C. Yang, a near-threatened species important for forestry and wood utilization in China. We identified 61 PbGLK genes which were classified into seven subfamilies. Our analyses of their phylogenetic relationships, gene structures, and chromosomal distribution revealed diverse characteristics. Expression profiling under different tissues and abiotic stresses showed that PbGLK25 and PbGLK30 were particularly responsive to drought, heat, light, and shade stresses, with significant upregulation. These findings highlight the potential role of PbGLK genes in stress adaptation and provide insights for the genetic improvement of P. bournei. Full article

Background: Pepper (Capsicum annuum L.) is a widely cultivated vegetable crop worldwide, with its rich fruit colors providing unique visual traits and economic value. This study investigated the genetic basis of the immature green fruit color by constructing a F₂ segregating population derived from a cross between yellow fruit C20 and green fruit C62 parent lines. Methods: Bulked segregant analysis sequencing (BSA-seq) was performed to identify genomic regions associated with fruit color. Candidate genes were pinpointed through functional annotation and genetic variation analysis, supported by SNP markers, genotype analysis, and transcriptome profiling. Results: Two genomic regions associated with fruit color were identified on chromosomes 1 (14.55–20.85 Mb) and 10 (10.15–22.85 Mb), corresponding to previously reported loci pc1 and pc10.1. Two chlorophyll synthesis-related genes, CaAPRR2 and CaGLK2, were identified as candidate regulators of fruit color. Mutations in these genes include a premature stop codon in both CaGLK2 and CaAPRR2. The mutation of CaAPRR2 and CaGLK2 jointly regulate the yellow fruit trait in pepper, with CaGLK2 being the major gene and CaAPRR2 being the minor gene. Transcriptome analysis showed that the expression levels of the two genes increased during the green ripening stage of the parent fruits, with higher expression levels of CaGLK2. Conclusions: This study identifies CaGLK2 and CaAPRR2 as key regulators of immature green fruit color in pepper, with CaGLK2 playing a predominant role. These findings provide a theoretical foundation and data support for elucidating the molecular regulatory mechanisms of fruit color and advancing marker-assisted breeding in pepper. Full article

In plants, hexokinase (HXK) is a kind of bifunctional enzyme involved in sugar metabolism and sugar signal transduction that plays important roles in plant growth and development and stress response. Some HXK genes without a phosphorylation function have been found in Arabidopsis, tobacco, etc., but these genes have not been identified in tomato. Therefore, further genome-wide systematic identification and characterization is necessary for tomato HXK genes. In this study, six HXK genes were identified from the tomato genome distributed across six different chromosomes, named SlHXK1-6. Gene structure analysis showed that the SlHXK genes contain the same number of introns and exons. Gene duplication and collinearity analysis revealed two pairs of tandem repeats among SlHXKs, and a higher collinearity between tomatoes and potatoes were found. Response elements associated with phytohormones, abiotic stresses, and growth and development were identified in the promoter sequences of SlHXKs. Quantitative real-time PCR (qRT-PCR) results further indicated the potential role of SlHXKs in tomato development and stress responses. The expression levels of most SlHXKs were significantly induced by abiotic stress, hormone, and sugar solution treatments. In particular, the expression of SlHXK1 was significantly induced by various treatments. Functional complementation experiments were performed using HXK-deficient yeast strain YSH7.4-3C (hxk1, hxk2, and glk1), and the results showed that SlHXK5 and SlHXK6 were unable to phosphorylate glucose and fructose in yeast. In conclusion, these results provide valuable foundations for further exploring the sugar metabolism and sugar signal transduction mechanisms of HXK and the functions of SlHXK genes in various abiotic stresses, and some SlHXKs may be key genes for enhancing plants’ tolerance to abiotic stresses. Full article

Spiroplasma citri, a bacterium from the class Mollicutes, is the causative agent of citrus stubborn disease, a serious threat to Moroccan citrus crops, with yield losses reaching 45%. Despite its long-standing presence since 1949 and regulations mandating disease-free citrus plants, data on S. citri in Morocco remain scarce. This study investigates the pathogenicity and symptom variability of Moroccan S. citri isolates using biological indexing and genetic mapping based on the Spiralin and P58 genes. Biological indexing through reverse inoculation revealed that seven out of ten isolates caused moderate to intense symptoms within 8 to 10 weeks, with symptom severity varying across citrus cultivars and regions. These findings suggest variations in pathogen titer. Molecular analysis showed that Moroccan isolates (27GH, 3GH, 8GH, 56MK, 16MK, 60MK, 2GLK, 13SS, and 30S1) exhibited complete (100%) sequence similarity with each other and the reference strain R2-A8. Furthermore, these isolates displayed a high degree of similarity (99.75%) to a Corsican isolate (U13995) and a 94% similarity to an Iranian isolate (KP666137). Analysis of the P58 gene confirmed a high level of homogeneity with Moroccan reference strain R8-A2, closely aligning (99.75%) with the American BR3-3X strain, and 98% similarity to isolates from Syria and Iran. This study lays a foundational insight into the molecular characterization of S. citri in Morocco and provides a groundwork for future research into managing citrus stubborn disease. Full article

The Golden2-like (GLK) transcription factors belong to the GARP family of transcription factors and play significant roles in plant growth, development, and responses to both abiotic and biotic stresses. This study employed bioinformatics and expression analyses to investigate the regulatory roles of wheat GLK proteins under various stress conditions, including abscisic acid (ABA) treatment, osmotic stress, and infection by Fusarium graminearum. The study identified 125 TaGLK proteins and revealed that TaGLKs play a significant role in wheat’s development and response to adverse environmental conditions. The results indicate that TaGLKs may serve as potential transcriptional regulators capable of integrating multiple cellular signals to coordinate various developmental and physiological processes. Evolutionary analysis classified the TaGLK proteins into six subgroups, which shared similar conserved domains and motifs. Protein–protein interaction network analysis revealed that TaGLKs are involved in photoreceptor activity, cell cycle progression, and protein regulation. Gene expression analysis of TaGLKs discovered that they play key functions in wheat development, as well as regulation of biotic and abiotic stress conditions. RT-qPCR analysis showed that TaGLKs regulate earlier and late effects of osmotic stress, F. graminearum infections, and ABA treatment in wheat. These findings provide knowledge for future studies of the functions of TaGLK TFs in wheat stress tolerance and development, which could have significant implications for enhancing wheat tolerance to various environmental stressors. Full article