Planta最新文献

Key message: This study characterizes wild-type and mutants of rice for culm strength at morphological, histological, and molecular levels, identifying key genes and genomic regions that govern the strong culm trait. Strong culm trait in rice has gained importance for sustainability in the realm of climate change. The mutants having economic important traits have become a potential source for the identification of genomic regions. The present study aimed to characterize rice mutants having strong culms and to identify genomic regions through conventional as well as NGS-based mapping approaches. Morphological characterization of Samba Mahsuri mutants with strong culms showed that they had a greater culm diameter and physical strength than the wild type. Histological analysis confirmed the morphological parameters, which included increased thickness in culm tissue, wider intervascular bundle spacing, and thicker lignified epi- and sub-epidermal layers, as well as parenchymal layers. Exploring one of the chemically mutagenized Samba Mahsuri mutants, SB170-B having strong culm, a genetic linkage map was constructed and identified four novel QTLs: qSC-5 (chromosome 5), qSC-6a (chromosome 6), qSC-6b (chromosome 6), and qSC-10 (chromosome 10), explaining 23.76%, 21.60%, 15.40%, and 40.50% of the phenotypic variance for strong culm, respectively. MutMap, an NGS-based analysis of the weak and strong culm pools from the F₂ population derived from SB170-B×BPT 5204, also identified a genomic region (27.0-29.6 Mb) which was corresponding to the qSC-5. This genomic region comprised of 17 genic SNPs, which converted into kompetitive allele-specific PCR (KASP) assays. Among those, one KASP marker, KASP 5-2 (chr5:27972606; C/T), located in the gene LOC_Os05g48810, which encodes a DNA/J-binding protein was shown strong co-segregation with the strong culm trait, indicating its potential to use in improvement of strong culm trait through molecular breeding.

Main conclusion: The 1, 8-Cineole synthase promoter directs the specific expression of Green Fluorescent Protein (GFP) in Lavandula latifolia glandular trichomes, and can help improve monoterpene metabolism in lavender through metabolic engineering. Lavender produces large amounts of a monoterpene-rich essential oil (EO) in glandular trichomes (GTs) present on its aerial parts. There is significant interest in improving EO quality and yield, and in using lavender GTs as bio-factories for mass-producing specialized metabolites, in particular terpenoids. Metabolic engineering is often carried out using constitutive promoters, like CaMV 35S, to drive terpene synthase gene expression. However, this non-specific expression can cause metabolite accumulation in non-specialized cells, potentially leading to cytotoxicity. GT-specific promoters offer a superior approach, confining terpene biosynthesis exclusively to the GTs' secretory cells. This study evaluated the GT specificity of four fragments of the L. x intermedia 1,8-cineole synthase (LiCINS) promoter region in stably transformed L. latifolia plants. Initial transformation using the β-glucuronidase (GUS) reporter gene resulted in inconsistent staining, even in CaMV 35S positive controls. To overcome this limitation, we generated new L. latifolia transformants in which the promoter fragments were used to drive the expression of the Green Fluorescent Protein (GFP). GFP fluorescence provided clear visualization of expression in leaf cells, including the GT secretory cells. The full-length promoter fragment (LiCINS-F1) exhibited exclusive GT-specific activity. In stark contrast, the shorter fragments (LiCINS-F2, LiCINS-F3, and LiCINS-F4) drove strong but non-specific GUS/GFP expression. These results confirm that the GT-specific promoter LiCINS-F1 is a valuable tool for metabolic engineering. By restricting the production of rare and valuable terpenes or other compounds exclusively to GTs, this approach allows the trichomes to function as specialized plant bio-factories without compromising the plant's overall wellbeing.

Main conclusion: A. hybridus tolerance to salinity depends on constitutively active mechanisms, whereas A. hypochondriacus tolerance to salt and water deficit depends on a constitutive protection and a robust transcriptional response. Drought and soil salinity are two environmental factors that significantly affect crop production. To gain a better understanding of how amaranth responds to these abiotic stresses, we analyzed the transcriptomic and metabolomic changes in the leaves of Amaranthus hybridus, a wild species, and A. hypochondriacus, a cultivated species used for seed production. We identified differentially expressed genes (DEGs) between the two species and under different stress conditions. Control plants of A. hypochondriacus exhibited higher expression levels of genes associated with photosynthesis, amino acid metabolism, fatty acid metabolism, sulfur metabolism, thiamine metabolism, and secondary metabolism. Notably, A. hybridus under salt stress showed an up-regulation of genes related to phosphonate and phosphinate metabolism and steroid biosynthesis. In contrast, the response of A. hypochondriacus to salt stress was characterized by increased expression of ABC transporters and genes involved in fructose, mannose, trehalose, porphyrin, thiamine, and monoterpenoid metabolism. When subjected to both types of stresses, A. hypochondriacus showed up-regulation of MAPK signaling pathways, ABC transporters, galactose, branched-chain amino acid (BCAA) degradation, and the production of defense compounds. Both amaranth species modulated their metabolic processes in response to drought and salinity stress towards cell wall modification, as well as the metabolism of pectin and lignin, while also producing antimicrobial and antifungal metabolites. Additionally, we detected differential accumulation of compounds, including methylphosphonate, 2-hydroxyethylphosphonate, and several metabolites related to fatty acid metabolism in the leaves of both amaranth species.

Main conclusion: The review highlights PGPR (e.g., Pseudomonas spp.) as sustainable, low-cost solution to mitigate drought and Fusarium stress in maize, enhancing yield and resilience. Maize (Zea mays L.) is a vital staple crop worldwide, yet its productivity is under growing pressure from the combined effects of drought and Fusarium verticillioides infection. These stresses often occur together, compounding the damage. Drought limits water availability, disrupts nutrient uptake, and slows photosynthesis, while also making plants more vulnerable to disease. In turn, F. verticillioides harms plant tissues, contaminates grain with fumonisins, and can further intensify water stress. Conventional approaches such as irrigation, fungicides, and resistant cultivars often fall short when both stresses occur simultaneously. In recent years, plant growth-promoting rhizobacteria (PGPR), particularly Pseudomonas spp., have gained attention as eco-friendly partners in managing these challenges. These beneficial bacteria support maize growth by improving nutrient availability, regulating plant hormones, enhancing osmoprotectants' production, activating antioxidant defenses, and suppressing pathogens through antifungal compounds, competitive root colonization, and induced systemic resistance. Findings from single-stress experiments show that Pseudomonas endophytes can boost drought tolerance by maintaining osmotic balance and antioxidant activity, while also limiting F. verticillioides infection and toxin production. However, studies examining their effectiveness under the combined pressures of drought and fungal attack remain limited. This review brings together current knowledge on the mechanisms, case studies, and practical constraints of Pseudomonas-mediated stress relief in maize, highlighting research gaps and setting priorities for strain selection, microbial consortia design, and large-scale field testing. Harnessing these bacteria could be a key step toward building climate-resilient maize production systems that protect both yields and grain safety in an era of environmental uncertainty.

Main conclusion: The study developed a synthetic FM promoter through domain shuffling of pararetroviral promoters, achieving 4-fold higher activity than CaMV35S in plants. It enhanced recombinant protein yields, demonstrated by effective scytovirin production against Chikungunya, proving FM's utility in plant synthetic biology and molecular farming. Plant synthetic biology requires high-performance constitutive promoters to maximise recombinant protein yields. In this study, we developed a synthetic promoter (FM) through strategic intermolecular domain shuffling of key regulatory regions derived from the full-length transcript promoters of Figwort mosaic virus (FMV) and Mirabilis mosaic virus (MMV). Functional characterization in transient systems demonstrated that this promoter drives exceptionally strong expression of reporter genes across three model plant species: Nicotiana tabacum, Nicotiana benthamiana, and Petunia × atkinsiana. Quantitative β-glucuronidase (GUS) assays revealed that the FM promoter exhibits 4.0-fold higher activity than the conventional CaMV35S promoter in tobacco, and also outperformed the modified CaMV35S2 promoter by 2.0-fold. These results were further validated in stable transgenic lines of N. tabacum and A. thaliana, where qRT-PCR and histochemical staining consistently showed superior transgene expression relative to CaMV35S controls. Through systematic mutagenesis analysis of the FM promoter, we identified that the as-1, G-Box, and ABRE cis-elements are critical for its high activity. We further demonstrated the promoter's compatibility with orthogonal regulation systems by enhancing FM-driven expression using CRISPR-dCas9/VP64 synthetic transcriptional activation. To evaluate biotechnological applications, an antiviral peptide scytovirin (SVN) was expressed under the control of the FM promoter in transgenic N. tabacum plants. In vitro antiviral assays against Chikungunya virus (CHIKV) confirmed that the plant-produced SVN retained biological activity and significantly reduced viral titers by 60%. These results collectively demonstrate the FM as a compact, high-performance synthetic promoter, making it especially valuable for plant molecular farming.

Main conclusion: This study presents the first complete plastome sequences for highly threatened Malagasy rosewood species, filling a critical genomic gap, clarifying their evolutionary relationships, and identifies polymorphic loci for molecular marker development to enhance species delimitation, and sustainable management. The biodiversity hotspot of Madagascar is not only home to many endemic species of Dalbergia but also arguably the epicenter of an escalating rosewood massacre, driven by the global demand for some of the world's most coveted tropical timbers. Malagasy rosewoods, among the planet's most valuable and endangered timbers, face extreme extinction risks as a consequence of unsustainable exploitation, illegal logging, habitat loss, mining, weak governance, ineffective regulation, corruption, and political instability, despite being listed under CITES and protected by a national decree No. 2016-801. The lack of genomic resources undermines our understanding of evolutionary relationships and hinders the crucial law enforcement required in the ongoing conservation efforts. To date, no plastome sequences have been available for Malagasy Dalbergia species, creating a significant gap in genomic resources. This study bridges this knowledge gap by presenting the first de novo assembled complete plastid genome sequences for five highly threatened Malagasy rosewoods, namely, D. monticola, D. bathiei, D. maritima, D. louvelii, and D. greveana. All plastomes exhibited classical quadripartite structure with genome sizes ranging from 153,602 to 156,580 bp. Each plastome contains 127 genes, including 83 protein-coding genes, 8 rRNA genes, and 36 tRNA gene, with several gene losses (psbL and rpl22) and gene duplications (rpl2, rpl23, rps7, and ycf2) across the plastomes. Comparative analysis identified eight hypervariable intergenic regions, and 550 polymorphic simple-sequence repeats (SSRs), forming a toolkit for species delimitation, and conservation genetics. Phylogenomic analysis, based on 118 plastomes representing 42 species generated a robust, well-resolved phylogenetic hypothesis, clarifying the previously ambiguous evolutionary relationships. The analysis revealed that Malagasy species do not form a monophylum but rather share a complex evolutionary history with geographically distant Dalbergia species. Codon-usage analysis revealed strong GC bias, whereas relaxed purifying selection in genes, such as accD, clpP, and rpl2, indicated local adaptation across Madagascar's diverse environments. These findings not only fill a critical genomic gap but also provide essential tools for enhancing conservation research, law enforcement, and sustainable management of these highly valuable taxa, and establishing a genomic framework applicable to other CITES-listed tropical timber species.

Main conclusion: In liverworts, phototropin senses the actual temperature rather than temperature differences and switches from cis- to trans-autophosphorylation to trigger the cold-avoidance response of chloroplast movement. Blue-light (BL)-induced chloroplast movement in plant cells is temperature-dependent. At standard growth temperatures, chloroplasts move toward weak BL-irradiated regions (accumulation response), maximizing photoreception, whereas at lower temperatures they move away from the irradiated area (cold-avoidance response), reducing photodamage. This temperature-dependent switch in the chloroplast response is mediated by phototropin (phot), a BL receptor and thermosensor, which contains a kinase domain and undergoes cis- and trans-autophosphorylation in response to BL and temperature. Under weak BL conditions, phot autophosphorylates in cis at standard growth temperatures and in both cis and trans at lower temperatures. However, it remains unclear whether phot senses actual temperatures or relative temperature changes to regulate chloroplast movement via autophosphorylation. In this study, we analyzed phot-mediated chloroplast movement in the liverwort Marchantia polymorpha under varying temperature conditions. We determined that chloroplast movement responds to actual temperatures rather than temperature differences and confirmed that phot is responsible for sensing actual temperatures in planta. Phot continuously monitors the actual temperature and increases its autophosphorylation levels as temperature decreases. The threshold temperature for the transition between the accumulation response and the cold-avoidance response corresponds to that for the switch from cis- to trans-autophosphorylation of phot. Our findings reveal that phot serves as an actual temperature sensor in planta to regulate chloroplast movement through autophosphorylation mode switching.

Main conclusion: In Rosa chinensis, four distinct polyisoprenoid families, including two very long-chain types, are synthesized by only three cis-prenyltransferases, challenging the traditional one-enzyme-one-family model. The presence of very long polyisoprenoids in leaves and young shoots is most probably involved in plant organ development. Although terpenoids in roses have been extensively studied, the polyisoprenoid fraction has remained unexplored. In this work, we provide the first characterization of polyisoprenoid diversity and biosynthesis in roses, revealing unexpected chemical and enzymatic complexity. Four distinct polyisoprenoid families (7-9, 15-25, 26-34, and 35-50 isoprene units) were identified in Rosa chinensis, with very long-chain compounds accumulated in leaves and young shoots. We functionally characterized three cis-prenyltransferases (CPTs) and a CPT-binding partner, RcNUS1, involved in their biosynthesis. The chloroplast-localized RcCPT2 synthesizes short-chain polyisoprenoids, whereas two endoplasmic reticulum-localized heteromeric enzymes, RcCPT1 and RcCPT3, require RcNUS1 as a partner to produce longer-chain compounds. Phylogenetic analysis revealed strong evolutionary conservation but notable species-specific diversification of these enzymes. Remarkably, the number of polyisoprenoid families exceeded the number of identified CPTs, challenging the long-standing one-enzyme-one-product paradigm and suggesting additional, yet unidentified mechanisms regulating chain length. To explore their potential functions, we analyzed the effects of temperature, light, and leaf age on polyisoprenoid accumulation. Environmental treatment had little effect, but leaf aging caused a marked increase in long-chain polyisoprenoids, suggesting roles in development and physiological stability. Our findings reveal new aspects of polyisoprenoid metabolism and highlight their potential functional diversity in plants.

Main conclusion: Hierarchical ROS network regulating rice root iron plaque formation, Fe speciation, mineral crystallinity, and absorption of nutrient elements has been revealed. The root iron plaque (RIP) of rice plays a critical role in heavy metal adsorption and rhizosphere environment regulation. However, the regulatory mechanisms of reactive oxygen species (ROS) in RIP formation remain poorly understood. This study investigated hydroponically cultivated rice under Fe(II) concentration gradients (50-200 mg L^-1) and water management regimes [contrast of continuous waterlogging (CW) with alternate wetting and drying (AWD)]. Using ROS scavengers [Cu(II), DMTU, TBA] to specifically inhibit O₂·^-, H₂O₂, and ·OH generation, we systematically elucidated ROS-mediated regulation of RIP formation, Fe redox speciation, and mineralogical structure. Key findings include: (i) ROS scavenging experiments revealed O₂·^- as the dominant contributor to RIP formation (17.55 ± 0.89% reduction after scavenging), followed by H₂O₂ (11.86 ± 0.45%) and ·OH (6.35 ± 0.34%); (ii) O₂·^- depletion reduced Fe(III)/Fe(II) ratios from 4:1 to 1:1, suppressed crystalline mineral formation (e.g., hematite), and increased weakly crystalline siderite proportions; (iii) XPS and XRD analyses demonstrated that ROS drive Fe(II) oxidation and mineral phase transitions by oxidative chain reactions (O₂·^- → H₂O₂ → ·OH), with O₂·^- being pivotal for maintaining high oxidation states and crystallinity in RIP. (iv) The mineral crystallinity of RIP affects its regulatory effect on nutrient elements. Scavenging O₂·^- treatment results in low crystallinity of RIP, which weakens its adsorption and fixation capacity for trace elements, such as Mn, Zn, and Cu. Consequently, the contents of Mn, Zn, and Cu in the iron plaque are low, while their contents in rice plants are high. This study unveils a hierarchical ROS regulatory network governing RIP formation, providing theoretical foundations for optimizing RIP functionality through water management strategies.

Main conclusion: GmCP3 in soybean seed vacuoles is a candidate processing enzyme of β-conglycinin subunits. However, a different type of proteases may be involved in unconventional secretion of β-conglycinin propeptides. Soybean β-conglycinin subunits, a 7S vicilin class of seed storage proteins (SSPs) of seed vacuoles, are subject to proteolytic cleavage of the N-terminal propeptide for subunit maturation. Unlike other SSPs, this process is independent of asparagine residues. It occurs at the C-terminal of lysine residues, indicating the involvement of unidentified processing enzymes outside the vacuolar processing enzyme (VPE) family of proteases. In this study, we hypothesized that GmCP3, a seed-specific vacuolar protease belonging to the papain-like cysteine protease (PLCP) family, might be responsible for this process and analyzed the relationship between its accumulation and processing. The results showed that GmCP3 accumulated abundantly during the synthesis of β-conglycinin subunits and significantly decreased once the processing was complete. Immunoelectron microscopy of developing seed cells showed the accumulation of both, GmCP3 and β-conglycinin propeptides, in vacuolar-associated compartments, such as protein storage vacuoles (PSVs) and prevacuolar compartments (PVCs). Unexpectedly, labeling specific of the propeptide region of β-conglycinin subunits, but not the mature subunit region, was observed in extracellular regions. These results indicate that GmCP3 is a possible candidate β-conglycinin processing enzyme of vacuoles, though other proteases may have a role in the secretion of propeptides.