Stress biology最新文献

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.

It remains a great challenge to control weeds in rapeseed fields in China. Breeding herbicide-resistant rapeseed varieties and using corresponding herbicide formulations has become the most economical and effective way to control weeds in rapeseed field. Characterization of more herbicide-resistant genetic resources will provide opportunities for breeders to develop rapeseed herbicide-resistant varieties with good agronomic performance. Previously, we obtained the tribenuron methyl (TBM)-resistant mutant K4 from ZS9 (Brassica napus L.) through ethyl methyl sulfonate mutagenesis and TBM foliar-spray screening. In this study, the inheritance and molecular characterization of the mutant K4 are carried out. Genetic investigation indicated that the herbicide-resistance of the K4 was controlled by one dominant allele at a single nuclear gene locus. Molecular characterization showed that a single point substitution at position 535 from C to T in BnAHAS3 (BnAHAS3^535T), which resulted in a mutation at point 179 in BnAHAS3. The K4 showed a certain degree of resistance to TBM, bensulfuron methyl, and monosulfon sodium, which were 50, 30, and 5 times that of ZS9, respectively. AHAS enzyme assay, structural analysis of AHAS proteins, affinity detection between TBM and BnAHAS3 by surface plasmon resonance analysis, and the transgenic experiment in Arabidopsis using BnAHAS3^535T confirmed that BnAHAS3^535T endow the K4 with herbicides resistance. In addition, an allele-specific marker was developed to quickly distinguish the heterozygous and homozygous mutated alleles BnAHAS3^535T. In conclusion, our research identified and characterized one novel mutative AHAS allele in B. napus and enriched genetic resource for developing herbicide-resistant rapeseed cultivars.

Fruit quality and yield are reduced when cucumber (Cucumis sativus L.) plants are exposed to low temperature (LT) stress, yet, the inheritance and genes linked to cold tolerance in adult plants have not been reported yet. Here, the LT-tolerance of 120 cucumber accessions representing four ecotypes were evaluated by GWAS, and also, in 140 recombinant inbred lines (RILs) derived from a biparental cross. Plants were exposed to naturally occurring LT environments in a plastic greenhouse, in winter 2022, and 2023, and a low temperature injury index (LTII) was employed to evaluate plant performance. Genetic analysis revealed that the LT-tolerance evaluated in the adult cucumber plants was a multigenic quantitative trait, and that 18 of the 120 accessions were highly LT tolerant by our LTII assessment. Two loci (gLTT1.1 and gLTT3.1) exhibited strong signals that were consistent and stable in two environments. In addition, two QTLs-qLTT1.2 on chromosome (Chr.) 1, and qLTT3.1 on Chr. 3, were discovered in all tests using RIL population derived from a cross between LT-sensitive 'CsIVF0106', and LT-tolerant 'CsIVF0168'. qLTT1.2 was delimited to a 1.24-Mb region and qLTT3.1 was narrowed to a 1.43-Mb region. Interestingly, a peak single nucleotide polymorphism (SNP) at gLTT1.1 and gLTT3.1 was also found in qLTT1.2 and qLTT3.1, respectively. These loci were thus renamed as gLTT1.1 and gLTT3.1. In these regions, 25 genes were associated with the LT response. By identifying differences in haplotypes and transcript profiles among these genes, we identified four candidates: CsaV3_1G012520 (an ethylene-responsive transcription factor) and CsaV3_1G013060 (a RING/U-box superfamily protein) in gLTT1.1, and two RING-type E3 ubiquitin transferases at CsaV3_3G018440 and CsaV3_3G017700 in gLTT3.1 that may regulate LT-tolerance in adult cucumber. Interestingly, the accessions in which the LT-tolerant haplotypes for two loci were pyramided, displayed maximally high tolerance for LT. These findings therefore provide a solid foundation for the identification of LT-tolerant genes and the molecular breeding of cucumber with LT-tolerance.