Stress biology最新文献

Zur (zinc uptake regulator), a member of the Fur (ferric uptake regulator) family of transcriptional regulators, plays multifaceted roles by regulating the gene expressions, such as modulating zinc ion uptake by regulating the znuABC gene cluster and influencing bacterial motility by modulating genes associated with flagella or pili. The photosynthetic autotroph Synechocystis sp. PCC 6803 is frequently used as an indicator organism for water pollution and a cell factory for high-value biochemical production in synthetic biology. During its growth, this organism often encounters various abiotic stresses, including oxidative, salt, and antibiotic stress. In this study, we conducted transcriptomic analysis on both Δzur mutant and wild-type (WT) strains to identify potential Zur-regulated genes in Synechocystis sp. PCC 6803. These genes primarily participate in multiple pathways such as inorganic ion transport, carbohydrate transport, energy production and conversion, and cell motility. Zur not only controls zinc ion homeostasis within the cell but also influences the iron balance by directly regulating the expression of the fur gene. In terms of motility, Zur regulates the expression of bacterial pili gene cluster and other motility-related genes, thereby affecting the twitching motility of Synechocystis sp. PCC 6803. Furthermore, Zur plays a crucial role in promoting biofilm formation and enhancing resistance to salt, oxidative, and antibiotic stresses by modulating relative gene expression. In conclusion, as a global transcriptional regulator, Zur plays pivotal roles in metal ion homeostasis, motility, and resistance to multiple stresses in Synechocystis sp. PCC 6803. This study illustrates the Zur regulons in Synechocystis sp. PCC 6803, and underscores the importance of Zur in enhancing the environmental adaptability of cyanobacteria.

Rapeseed (Brassica napus L.) is a globally important oil crop, providing edible vegetable oil and other valuable sources for humans. Being an allotetraploid, rapeseed has a complex genome that has undergone whole-genome duplication, making molecular breeding rather difficult. Fortunately, clustered regularly interspacedshort palindromic repeat (CRISPR)/CRISPR-associated (Cas) technologies have emerged as a potent tool in plant breeding, providing unprecedented accuracy as well as effectiveness in genome editing. This review focuses on the application and progresses of CRISPR/Cas technologies in rapeseed. We discussed the principles and mechanisms of CRISPR/Cas systems focusing on their use in rapeseed improvement such as targeted gene knockout, gene editing and transcriptional regulation. Furthermore, we summarized the regulatory frameworks governing CRISPR-edited crops as well as the challenges and opportunities for their commercialization and adoption. The potential advantages of CRISPR-mediated traits in rapeseed such as increased yield, disease and stress resistance and oil quality are discussed along with biosafety and environmental implications. The purpose of this review is to provide insights into the transformative role of CRISPR/Cas technologies in rapeseed breeding and its potential to address global agricultural challenges while ensuring sustainable crop production.

The fungicide metconazole, which acts as a sterol 14α-demethylation inhibitor (DMI), can exhibit strong inhibitory effects on Fusarium pseudograminearum. However, the resistance mechanism as well as the risk that F. pseudograminearum develops resistance to metconazole is yet to be fully assessed. In this study, metconazole displayed a mean EC₅₀ value of 0.0559 μg/mL against 105 F. pseudograminearum isolates. Ten sensitive parental isolates were then subjected to fungicide adaptation to generate resistant mutants, with in vitro experiments subsequently highlighting the inferior fitness of the mutants. In addition, metconazole exhibited positive cross-resistance with both mefentrifluconazole and tebuconazole. Altogether, the results confirmed the low risk that F. pseudograminearum develops resistance to metconazole. Finally, a mutation genotype (M151T) was identified in FpCYP51B, with the mutants also overexpressing the FpCYP51 genes. Subsequent molecular docking and transformation-based experiments indicated that M151T substitution and overexpression in FpCYP51 genes conferred resistance to metconazole in F. pseudograminearum.

The fungus Puccinia striiformis f. sp. tritici (Pst) is the causal agent of wheat stripe rust which constitutes a major limitation to wheat production. Cloning and applying disease-resistant genes are considered as an effective solution. Chinese wheat cultivar Xingzi 9104 (XZ9104) has exhibited durable resistance across multiple environments since its release. Through quantitative trait loci (QTL) analysis, eight QTL were found on chromosome arms 1BS, 1BL, 2AL, 2BL, 3BS, 4BL, 5BL and 7BL. YrXZ identified as 1RS.1BL translocation conferred race-specific all-stage resistance to Pst race CYR23. QYrxz.nwafu-1BL.6 and QYrxz.nwafu-3BS.7 were considered as the adult plant resistance genes Yr29 and Yr30, respectively. Notably, QYrxz.nwafu-2BL.5 accounted for 15.75-47.63% of the phenotypic variation across diverse environments and its pyramiding with Yr29 and Yr30 can confer high level of resistance. Other QTL were environment-dependent with minor effects. To clone the above resistance genes, we created a population of over 2,000 M₅ mutants in XZ9104 using ethylmethane sulfonate (EMS) mutagenesis and screened various types of susceptible mutants. Using the MutIsoseq approach with five mutant lines susceptible to race CYR23, we rapid isolated a candidate gene for YrXZ encoding coiled-coil nucleotide-binding site leucine-rich repeat (CC-NBS-LRR) protein. Integrating cytological analysis, gene-based association analysis, transcriptomic profiling and virus-induced gene silencing (VIGS), we confirmed that the causal gene for YrXZ was indeed Yr9. This study demonstrated that multiple QTL with different effects contributed to the durable resistance in XZ9104. Understanding the molecular mechanisms and pathways involved in plant defense can inform future strategies for deploying resistance gene and engineering of genetic resistance against evolving diseases.

Aphids are highly destructive agricultural pests characterized by complex life cycles and phenotypic variability, facilitating their adaptation to diverse climates and host plants. Their feeding behavior leads to plant deformation, wilting, stunted growth, disease transmission, and significant yield losses. Given the economic risks aphids pose, regular updates on their seasonal behaviors, adaptive mechanisms, and destructive activities are critical for improving management strategies to mitigate crop losses. This review comprehensively synthesizes recent studies on aphids as plant pests, the extrinsic factors influencing their life cycles, and the intricate interactions between aphids and their hosts. It also highlights recent advancements in biological control measures, including natural enemies, antibiosis, and antixenosis. Additionally, we explore plant defense mechanisms against aphids, focusing on the roles of cell wall components such as lignin, pectin and callose deposition and the genetic regulations underlying these defenses. Aphids, however, can evolve specialized strategies to overcome general plant defenses, prompting the development of targeted mechanisms in plants, such as the use of resistance (R) genes against specific aphid species. Additionally, plant pattern recognition receptors (PRRs) recognize compounds in aphid saliva, which triggers enhanced phloem sealing and more focused immune responses. This work enhances understanding of aphid-plant interaction and plant resistance and identifies key research gaps for future studies.

InDel markers are commonly used to assess genetic relationships among populations. In this study, we employed a whole-genome sequence comparison method to identify and develop InDel markers for the rice blast fungus Pyricularia oryzae. We analyzed 152 whole-genome sequences of P. oryzae isolates from diverse global regions, including Brazil, Burundi, China, Colombia, Côte d'Ivoire, France, Ghana, Hungary, India, Japan, Korea, Laos, Madagascar, Mali, Morocco, Nepal, the Philippines, Portugal, Spain, Suriname, Thailand, the UK, the USA, and Zambia. Our analysis identified a total of 233,595 InDel loci distributed across the seven chromosomes of P. oryzae. From these, 82 loci were selected based on their high polymorphism across the 152 genome sequences. The effectiveness of these 82 loci was assessed by analyzing the genetic diversity of 47 Thai rice blast isolates alongside two reference isolates, GUY11 (France) and KJ201 (Korea). Of the 82 InDel loci, 33 exhibited polymorphisms, with 2-4 alleles per locus and polymorphic information content (PIC) scores ranging from 0.04 to 0.67. Principal coordinate and structure analyses revealed two genetic subgroups among the Thai rice blast isolates, categorized according to host specificity. Genetic relationships highlighted disparities among rice blast populations based on their respective hosts: rice and grassy weeds. This finding suggests a correlation between genetic relatedness and the plant hosts susceptible to rice blast disease. The newly developed InDel markers provide a valuable resource for future research in this field.

Litchi, a fruit that is highly sought-after worldwide, faces significant yield challenges due to litchi downy blight, primarily caused by Phytophthora litchii. Fluopicolide has exhibited remarkable efficacy in inhibiting this pathogen and is utilized for the management of litchi downy blight. Although understanding the resistance of P. litchii to fluopicolide is critical, studies on its risk and mechanisms remain limited. In this study, we determined the sensitivity of 125 P. litchii isolates to fluopicolide, revealing an average EC₅₀ value of 0.131 ± 0.037 μg/mL. Through fungicide adaptation, four resistant mutants were obtained with resistance factors exceeding 600, indicating that these strains exhibited high levels of resistance. A compound fitness index analysis demonstrated that the survival fitness of resistant mutants was significantly lower than that of their parental strains. Cross-resistance assays revealed no cross-resistance between fluopicolide and other fungicides with different modes of action. However, positive cross-resistance was observed with fluopimomide. A comprehensive evaluation suggested a moderate risk of P. litchii developing resistance to fluopicolide. PlVHA-a^N771S and PlVHA-a^N846S point mutations in resistant mutants were identified by gene sequencing analyses. These two point mutations were validated as contributors to resistance in P. litchii through genetic transformation and molecular docking.

Reverse genetics research in complex hexaploid wheat often encounters challenges in determining the priority of gene functional characterization. This study aims to systematically analyze the wheat (Triticum aestivum) receptor-like kinase (TaRLK) gene family and develop an effective strategy to identify key candidate genes for further investigation. We identified 3,424 TaRLKs using bioinformatics methods and analyzed the diverse and conserved evolutionary relationships of RLKs among Arabidopsis, rice and wheat. Based on publicly available and our laboratory's transcriptome data, we comprehensively analyzed the transcriptional expression patterns of TaRLKs in response to various stresses, particularly Puccinia striiformis f. sp. tritici (Pst). The TaCrRLK1L16, which is upregulated during Pst infection and triggered cell death in Nicotiana benthamiana, has been identified as a key candidate gene for further functional characterization. Furthermore, our results suggested that the transgenic wheat overexpressing TaCrRLK1L16 significantly enhanced resistance to Pst. This study will provide valuable insights into understanding the evolutionary characteristics and expression patterns of TaRLKs while offering a novel strategy for determining the priority of key candidate TaRLKs.

Plants are engaged in a constant battle for survival against pathogens, which triggers a multifaceted immune response characterized by pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) to prevent infection. These two immune responses operate synergistically to enhance plant immunity. PTI is considered the first line of defense involving the recognition of pathogen-associated molecular patterns (PAMPs) by specific receptors in host cells known as pattern recognition receptors (PRRs), which initiate defense signaling. However, many pathogens often overcome the first line of defense (PTI) and successfully deploy effector proteins to promote virulence and subvert plant immunity, leading to host susceptibility. In the counter-defense, the ETI defense mechanism is activated by triggering resistance (R) genes in plants that usually encode nucleotide-binding-leucine-rich-containing (NLR) proteins. During plant-pathogen interactions, transcriptional reprogramming of defense-related genes such as pathogenesis-related proteins and generation of reactive oxygen species (ROS) are essential for facilitating programmed cell death at the infected location to inhibit pathogen proliferation. While ROS and PR protein are critical in plant-pathogen interaction, they are not universally required or effective against all pathogens. Hence, plants' multilayer immune layer is encrypted with the compensatory activation of ETI defense response towards the failure of one component of the defense system to maintain robust immunity.