Plant Cell Reports最新文献

Key message: OsACX4 knockout reduces peroxisomal oxidative stress, enhancing rice drought and salt tolerance through metabolic-redox rebalancing for climate-resilient breeding. Climate change is intensifying the frequency and severity of abiotic stress, such as salt and drought stresses, which severely limit rice productivity worldwide, necessitating the identification of molecular targets for crop improvement. This study provides the first comprehensive functional characterization of the peroxisomal acyl-CoA oxidase OsACX4 in rice (Oryza sativa L.) drought and salinity tolerance, revealing its unexpected role as a negative regulator of stress tolerance through modulation of cellular redox homeostasis. Through genome editing using CRISPR/Cas9-mediated knockout and overexpression approaches, we generated transgenic lines to investigate the function of OsACX4 under salt and drought stress. Knockout lines exhibited superior stress tolerance compared to the wild-type (WT) and overexpression lines, demonstrating significantly higher survival rates under severe stress conditions. Enhanced tolerance correlated with coordinated upregulation of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities. Knockout lines accumulated substantially higher proline (Pro) levels while maintaining markedly reduced reactive oxygen species (ROS) compared to overexpression lines. Transcriptional analysis revealed that OsACX4 disruption triggered upregulation of stress-responsive genes, including OsSOD1, OsDREB2A, OsDREB1B, and OsAPX1 under severe stress. Subcellular localization confirmed peroxisomal targeting of OsACX4, where its β-oxidation activity generates hydrogen peroxide (H₂O₂) as a metabolic by-product. Our results reveal a metabolic trade-off whereby stress-induced OsACX4 expression mobilizes energy reserves but compromises cellular redox homeostasis. The superior performance of knockout lines under both stresses demonstrates that strategic OsACX4 disruption enhances plant resilience, identifying this gene as a promising breeding target for developing climate-resilient rice varieties through precision genome editing.

Key message: Oil palm EgPRP1 promoter drives targeted gene expression in roots, providing a tool for root-trait modification and improving stress resilience. Root-trait modification for crop improvement through genetic engineering requires the availability of strong promoters capable of directing target gene expression in root. In this study, we have characterised the promoter of an oil palm proline-rich protein gene (EgPRP1) and conducted a 5' serial deletion analysis to delineate the cis-regulatory regions essential for transgene expression in root. The EgPRP1 promoter was shown to be functional in oil palm root tissue through transient expression analysis. Stable transformation in T₁ generation tobacco lines further demonstrated that the EgPRP1 construct, the RSP-3A (2000 bp), exhibited strong root-preferential promoter activity across all developmental stages of root growth. Notably, RSP-3A activity was also inducible by wounding, as indicated by localised GUS staining at incision sites on both flowers and leaves of mature transgenic plants. Through fine-scale promoter deletion, RSP-3D, the shortest construct (665 bp), was found to drive root-specific expression in mature root tissues. The results indicated that the promoter contains cis-acting elements functioning as negative regulators, potentially contributing to root specificity. In addition, the 5' UTR and ATATT motifs that were identified as ROOTMOTIFTAPOX1 elements were essential for strong promoter activity. The findings highlight the potential of the oil palm EgPRP1 promoter as a valuable molecular tool for root-targeted trait modification to improve crop yield, quality, and sustainability.

Key message: The mitochondrial gene ORF188 enhances salt stress tolerance in rapeseed by boosting ATP synthesis, thereby fueling antioxidant defense systems and maintaining cellular homeostasis. Soil salinity severely impairs crop productivity by inducing osmotic stress, ionic toxicity, and oxidative damage. An energy deficit, arising from impaired mitochondrial ATP production under stress, represents a critical bottleneck that compromises the plant's antioxidant capacity. Here, we report that the mitochondrial gene ORF188, a homolog of the ATP synthase F₀ subunit, significantly enhances salt stress tolerance in rapeseed. ORF188-overexpressing lines exhibited superior growth and reduced oxidative damage under salt stress, which was underpinned by constitutively elevated ATP synthase activity and cellular ATP levels. This energy surplus enhanced the antioxidant system, maintained favorable Na⁺/K⁺ ratio and orchestrated a homeostasis-oriented stress transcriptome. Crucially, treatment with the ATP synthase inhibitor Oligomycin A abolished both the salt-tolerant phenotype and the associated transcriptional reprogramming, thereby confirming the essential role of enhanced ATP synthesis. Our findings demonstrate that ORF188 as a key genetic determinant of salt stress tolerance via ATP-dependent antioxidant activation, and representing a promising target for breeding salt-resilient crops.

Key message: The bHLH transcription factor BoMYC2 played a critical role in regulating branching in ornamental kale via the BoMYC2-BoD27 cascade by transcriptionally repressing BoD27 to reduce strigolactone (SL) biosynthesis and promote branching. Branching plays a vital role in plant morphology. Ornamental kale is an emerging cold-season flower, branching is of great significance on its ornamental value. While the functional genes and corresponding mechanism of branching in ornamental kale remains unclear. Previously, we conducted transcriptome sequencing with a single-branched inbred line 'P29' and its multi-branched mutant. Among the differentially expressed genes, BoD27, a homologous gene of AtD27, was a candidate. In this study, we cloned the full-length and promoter sequences of the BoD27 gene between the single- and the multi-branched materials. The differences within the coding sequences led to eleven amino acids mutations, where three mutated amino acids located in the functional domain. The BoD27 protein localized in chloroplast under the laser scanning confocal microscope. Knockout and knockdown of the BoD27 gene both led to SLs content decrease and promoted the outgrowth of axillary buds. BoMYC2 was identified as an upstream inhibitory factor of BoD27 gene via Y1H and DLR assays. Overexpression of BoMYC2 promoted the numbers of branches by inhibiting Sls synthesis. This study revealed a novel regulatory cascade comprising BoD27 and its upstream inhibitor BoMYC2 that regulates branching in ornamental kale.

Key message: ANAC032 directly bind to the promoter regions of XTH31 and XTH33 and repress their expression, and loss-of-function xth31 mutant plants exhibited increased sensitivity to Ni stress, with phenotypes similar to those of NAC32-overexpressing plants.

Key message: We optimized soybean hairy root production for field trials using newly transformed Rhizobium rhizogenes, a 22 °C growth temperature, and GFP flashlight visualization. Roots are the primary organs for sensing abiotic and biotic stress factors originating in the soil. A critical biological question is whether root plasticity in response to these stresses influences whole-plant development. The generation of soybean chimeric plants with an altered root transcriptome offers a powerful approach to address this question. The existing protocols for this strategy typically require sterile conditions and produce a limited number of chimeric plants. We optimized the technique by introducing several key modifications, significantly enhancing its efficiency. The new protocol eliminates the requirement for sterile conditions in most steps. Moreover, fresh bacterial transformation for each experiment was performed, overcoming the loss of infection ability associated with storing cultures at - 80 °C, reaching 70-100% efficiency. The use of a specific flashlight helped to determine which roots were transgenic, avoiding destructive sampling. A previous transformation of cotyledons helped to select the colony with the highest infection ability. The optimal plant growth temperature was determined to be 22 °C. These combined changes and tips resulted in the consistent production of hundreds of chimeric plants, making them suitable for large-scale field trials. Results from subsequent field trials, performed over three seasons, with different constructs that overexpress or silence transcription factors, and confirmed that root transcriptome alterations impact whole-plant development.

Key message: Transient overexpression assays and RNA sequencing (RNA-seq) showed that the transcription factor HmPIF1 enhances lead (Pb) tolerance in Hydrangea by improving antioxidant capacity and altering transporter protein expression. Lead (Pb) soil contamination has caused serious ecological and environmental issues. Hydrangea represents a promising candidate species for phytoremediation, whereas research on its Pb-tolerant genes remains relatively limited. This study aimed to explore the Pb tolerance function of HmPIF1 at the physiological and transcriptional levels. Results showed that Pb stress significantly upregulated the expression of HmPIF1. Subcellular localization and transcriptional autoactivation assays demonstrated that HmPIF1 is a nuclear-localized transcription factor without transcriptional autoactivation activity. Transient overexpression experiments confirmed that eight substances, including glutathione reductase, superoxide dismutase, and total protein, were key physiological factors for HmPIF1-enhanced Pb tolerance in Hydrangea leaves, while transcriptomic analysis identified "photosynthesis" and "glutathione metabolism" as likely the core regulatory pathways. Furthermore, HmPIF1 overexpression promoted Pb accumulation in leaves, accompanied by differential expression of ion transporter proteins. Taken together, HmPIF1 positively regulates plant Pb tolerance and enhances Pb uptake in leaves, which may be achieved through multiple regulatory pathways including photosynthesis, antioxidation and ion transporter-mediated processes. These findings provide a theoretical basis for subsequent related research.

Key message: Polyploid rice exhibits superior cadmium tolerance via enhanced antioxidant activity, reduced Cd accumulation, and transporter regulation, with zinc nanoparticles further mitigating toxicity and modulating stress-responsive genes. Cadmium (Cd) contamination poses a serious threat to rice production by impairing plant growth and yield. To investigate the mechanisms of Cd tolerance, we compared diploid rice (E22) and its polyploid counterpart (T42) under Cd stress (50 mg kg^-1 soil) with or without zinc supplementation (25 mg kg^-1 soil). Upon Cd exposure, E22 exhibited a 7.8% decline in plant weight and seed set, while T42 experienced only a 4.71% reduction in plant weight, demonstrating its enhanced tolerance to Cd toxicity. Consistently, Cd accumulation was markedly lower in T42 across multiple tissues. Under Cd stress, T42 maintained lower levels of H₂O₂ and malondialdehyde while exhibiting enhanced antioxidant activity, including elevated peroxidase, superoxide dismutase, catalase, and glutathione, compared to E22. The more complete organelles in T42 likely contributed to its improved Cd tolerance. Notably, supplementation with ZnO-NPs reduced Cd accumulation in both diploid and polyploid rice. Transcriptomic analysis revealed that starch metabolism-related genes (OsISA1 and OsISA2) were strongly expressed in T42, whereas tubulin genes (OsTB16 and OsTB50) were strongly expressed in T42 under Zn treatment. In contrast, photosynthesis-related genes show remarkable differential expressions between E22 and T42, suggesting different adaptive strategies in E22 and T44, as evidenced by impaired photosynthesis in E22 under stress. Overall, these findings demonstrate that polyploid rice possesses enhanced resilience to Cd stress through coordinated regulation of tubulin, metal transporters, and antioxidant systems, with ZnO-NPs further mitigating Cd toxicity.

Key message: MT mitigates Cd toxicity by enhancing photosystem and antioxidant system activities, and related gene expression in GCC. NAC, HSF, and MYB-related families may play key roles in MT-induced Cd tolerance. Cadmium (Cd), a toxic heavy metal non-essential to plants, has detrimental impacts on both the environment and human health. Melatonin (MT) plays an important protective role in plants against stresses such as heavy metal toxicity. However, the detailed mechanism underlying MT alleviating Cd toxicity remains unclear in ground-cover chrysanthemum (Chrysanthemum morifolium Ramat., GCC). GCC seedlings were pre-treated with MT solution (150 μM) via foliar spraying and subsequently grown under Cd stress, after which the growth, physiological, and transcriptomic responses of the plant were investigated. The results demonstrated that MT pre-treatment inhibited the Cd-induced chlorophyll degradation in GCC seedlings, while it enhanced chlorophyll synthesis and related gene expression by promoting electron transfer efficiency and maintaining the integrity of the oxygen-evolving complex in photosynthesis. Furthermore, MT + Cd treatment upregulated 11 photosystem I (PSI), 13 PSII, eight light-harvesting complex I (LHCI), and 20 LHCII-related genes as compared with Cd treatment alone. MT also alleviated oxidative stress and boosted antioxidant capacity by conserving the activities and gene expression levels of superoxide dismutase, peroxidase, and key enzymes in the ascorbate-glutathione cycle and thioredoxin-peroxiredoxin pathway. In addition, MT reduced the generation rate of O₂^·- by 27.64%, malondialdehyde by 68.36%, and H₂O₂ by 44.97%, alleviating the Cd-induced damage. Weighted gene co-expression network analysis provided additional evidence that MT improved GCC tolerance to Cd by modulating the expression of transcription factors (e.g., NAC, HSF, and MYB-related families) related to abiotic stress.

Key message: Ambient pH affects the virulence of Phytophthora nicotianae and activates NtFERL2 to enhance the resistance of tobacco to Phytophthora nicotianae. Tobacco is a globally important economic crop and plays a crucial role in agricultural production and rural development. Tobacco black shank, caused by Phytophthora nicotianae, results in severe biomass and yield losses across all major tobacco-growing regions. Variations in soil pH are known to reshape crop-pathogen interactions and pose a threat to productivity, yet how ambient pH affects the occurrence of diseases in plants remains poorly understood. Here, we observed that acidic ambient pH was more conducive to the growth and pathogenicity of P. nicotianae, which was correlated with promoted sporulation and mycelial bulges under laboratory conditions. In tobacco plants, acidic ambient pH increased susceptibility to the pathogen, whereas alkaline pH reduced disease severity. Transcriptome analysis with tobacco plants under different pH regimes for 4 weeks showed that genes involved in the plant-pathogen interaction, oxidative phosphorylation and mitogen-activated protein kinase (MAPK) signaling pathway were differentially expressed. We identified a receptor-like kinase, FERONIA-like 2 (FERL2), as a resistance factor exhibiting pH-dependent expression variations. Overexpression of FERL2 attenuated resistance differences across pH conditions by activating downstream defense signaling pathways, suggesting its essential role in pH-modulated immunity. Our study demonstrates that acidic pH enhances P. nicotianae virulence and compromises resistance, potentially through impairing FERL2-mediated signaling, providing strategic insights for controlling tobacco black shank under varying soil pH conditions.