Molecular Plant-microbe Interactions最新文献

Cyst nematodes co-opt plant developmental programs for the establishment of a permanent feeding site called a syncytium in plant roots. In recent years, the role of plant developmental genes in syncytium formation has gained much attention. One main obstacle in studying the function of development-related genes in syncytium formation is that mutation or ectopic expression of such genes can cause pleiotropic phenotypes, making it difficult to interpret nematode-related phenotypes or, in some cases, impossible to carry out infection assays due to aberrant root development. Here, we tested three commonly used inducible gene expression systems for their application in beet cyst nematode infection assays of the model plant Arabidopsis thaliana. We found that even a low amount of ethanol diminished nematode development, deeming the ethanol-based system unsuitable for use in cyst nematode infection assays, whereas treatment with estradiol or dexamethasone did not negatively affect cyst nematode viability. Dose and time course responses showed that in both systems, a relatively low dose of inducer (1 μM) is sufficient to induce high transgene expression within 24 h of treatment. Transgene expression peaked at 3 to 5 days post-induction and began to decline thereafter, providing a perfect window for inducible transgenes to interfere with syncytium establishment while minimizing any adverse effects on root development. These results indicate that both estradiol- and dexamethasone-based inducible gene expression systems are suitable for cyst nematode infection assays. The employment of such systems provides a powerful tool to investigate the function of essential plant developmental genes in syncytium formation. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Temperature elevation drastically affects plant defense responses to Ralstonia solanacearum and inhibits the major source of resistance in Arabidopsis thaliana, which is mediated by the receptor pair RRS1-R/RPS4. In this study, we refined a previous genome-wide association (GWA) mapping analysis by using a local score approach and detected the primary cell wall CESA3 gene as a major gene involved in plant response to R. solanacearum at both 27°C and an elevated temperature, 30°C. We functionally validated CESA3 as a susceptibility gene involved in resistance to R. solanacearum at both 27 and 30°C through a reverse genetic approach. We provide evidence that the cesa3^mre1 mutant enhances resistance to bacterial disease and that resistance is associated with an alteration of root cell morphology conserved at elevated temperatures. However, even by forcing the entry of the bacterium to bypass the primary cell wall barrier, the cesa3^mre1 mutant still showed enhanced resistance to R. solanacearum with delayed onset of bacterial wilt symptoms. We demonstrated that the cesa3^mre1 mutant had constitutive expression of the defense-related gene VSP1, which is upregulated at elevated temperatures, and that during infection, its expression level is maintained higher than in the wild-type Col-0. In conclusion, this study reveals that alteration of the primary cell wall by mutating the cellulose synthase subunit CESA3 contributes to enhanced resistance to R. solanacearum, remaining effective under heat stress. We expect that these results will help to identify robust genetic sources of resistance to R. solanacearum in the context of global warming. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Stem rust, caused by the biotrophic fungal pathogen Puccinia graminis f. sp. tritici (Pgt), is an important disease of wheat. However, the majority of Pgt virulence/avirulence loci and underlying genes remain uncharacterized due to the constraints of developing bi-parental populations with this obligate biotroph. Genome-wide association studies (GWAS) using a sexual Pgt population mainly collected from the Pacific Northwestern United States were used to identify candidate virulence/avirulence effector genes corresponding to the six wheat Sr genes: Sr5, Sr21, Sr8a, Sr17, Sr9a, and Sr9d. The Pgt isolates were genotyped using whole-genome shotgun sequencing that identified approximately 1.2 million single nucleotide polymorphisms (SNPs) and were phenotyped at the seedling stage on six Sr gene differential lines. Association mapping analyses identified 17 Pgt loci associated with virulence or avirulence phenotypes on six Pgt resistance genes. Among these loci, 16 interacted with a specific Sr gene, indicating Sr-gene specific interactions. However, one avirulence locus interacted with two separate Sr genes (Sr9a and Sr17), suggesting two distinct Sr genes identifying a single avirulence effector. A total of 24 unique effector gene candidates were identified, and haplotype analysis suggests that within this population, AvrSr5, AvrSr21, AvrSr8a, AvrSr17, and AvrSr9a are dominant avirulence genes, while avrSr9d is a dominant virulence gene. The putative effector genes will be fundamental for future effector gene cloning efforts, allowing for further understanding of rust effector biology and the mechanisms underlying virulence evolution in Pgt with respect to race-specific R-genes. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Callose is a vital component in plant biology, contributing to essential processes like pollen maturation and defense against pathogens. However, misconceptions surrounding callose staining persist, particularly regarding the role of aniline blue. It is now known that commercial aniline blue contains sirofluor, and it is this fluorophore, rather than aniline blue itself, that is responsible for the observed fluorescence during callose detection. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Small RNAs (sRNAs) are involved in gene silencing in multiple ways, including through cross-kingdom transfers from parasites to their hosts. Little is known about the evolutionary mechanisms enabling eukaryotic microbes to evolve functional mimics of host small regulatory RNAs. Here, we describe the identification and functional characterization of SINE_sRNA1, an sRNA family derived from highly abundant short interspersed nuclear element (SINE) retrotransposons in the genome of the wheat powdery mildew pathogen. SINE_sRNA1 is encoded by a sequence motif that is conserved in multiple SINE families and corresponds to a functional plant microRNA (miRNA) mimic targeting Tae_AP1, a wheat gene encoding an aspartic protease only found in monocots. Tae_AP1 has a novel function enhancing both pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), thereby contributing to the cross activation of plant defenses. We conclude that SINE_sRNA1 and Tae_AP1 are functional innovations, suggesting the contribution of transposons to the evolutionary arms race between a parasite and its host. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

MicroRNAs (miRNAs) play an essential regulatory role in plant-virus interaction. However, few studies have focused on the roles of miRNAs and their targets after sugarcane mosaic virus (SCMV) infection in sugarcane. To address this issue, we conducted small RNA (sRNA) and degradome sequencing on two contrasting sugarcanes (SCMV-resistant 'Fuoguo1' [FG1] and susceptible 'Badila') infected by SCMV at five time points. A total of 1,578 miRNAs were profiled from 30 sRNA libraries, comprising 660 known miRNAs and 380 novel miRNAs. Differential expression analysis of miRNAs revealed that most were highly expressed during the SCMV exponential phase in Badila at 18 h postinfection, with expression profiles positively correlated with virus replication dynamics as observed through clustering. Analysis of degradome data indicated a higher number of differential miRNA targets in Badila compared to FG1 at 18 h postinfection. Gene ontology (GO) enrichment analysis significantly enriched the stimulus-response pathway, suggesting negative regulatory roles to SCMV resistance. Specifically, miR160 upregulated expression patterns and validated in Badila through quantitative real-time PCR (qRT-PCR) in the early stages of SCMV multiplication. Our research provides new insights into the dynamic response of plant miRNA and virus replication and contributes valuable information on the intricate interplay between miRNAs and SCMV infection dynamics. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Diphenyl ether herbicides are extensively utilized in agricultural systems, but their residues threaten the health of sensitive rotation crops. Functional microbial strains can degrade diphenyl ether herbicides in the rhizosphere of crops, facilitating the restoration of a healthy agricultural environment. However, the interplay between microorganisms and plants in diphenyl ether herbicides degradation remains unclear. Thus, the herbicide-degrading strain Bacillus sp. Za and the sensitive crop, maize, were employed to uncover the interaction mechanism. The degradation of diphenyl ether herbicides by strain Bacillus sp. Za was promoted by root exudates. The strain induced root exudate re-secretion in diphenyl ether herbicide-polluted maize. We further showed that root exudates enhanced the rhizosphere colonization and the biofilm biomass of strain Za, augmenting its capacity to degrade diphenyl ether herbicide. Root exudates regulated gene fliZ, which is pivotal in biofilm formation. Wild-type strain Za significantly reduced herbicide toxicity to maize compared to the ZaΔfliZ mutant. Moreover, root exudates promoted strain Za growth and chemotaxis, which was related to biofilm formation. This mutualistic relationship between the microorganisms and the plants demonstrates the significance of plant-microbe interactions in shaping diphenyl ether herbicide degradation in rhizosphere soils. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

The selective pressure of pathogen-host symbiosis drives adaptations. How these interactions shape the metabolism of pathogens is largely unknown. Here, we use comparative genomics to systematically analyze the metabolic networks of oomycetes, a diverse group of eukaryotes that includes saprotrophs as well as animal and plant pathogens, with the latter causing devastating diseases with significant economic and/or ecological impacts. In our analyses of 44 oomycete species, we uncover considerable variation in metabolism that can be linked to lifestyle differences. Comparisons of metabolic gene content reveal that plant pathogenic oomycetes have a bipartite metabolism consisting of a conserved core and an accessory set. The accessory set can be associated with the degradation of defense compounds produced by plants when challenged by pathogens. Obligate biotrophic oomycetes have smaller metabolic networks, and taxonomically distantly related biotrophic lineages display convergent evolution by repeated gene losses in both the conserved as well as the accessory set of metabolisms. When investigating to what extent the metabolic networks in obligate biotrophs differ from those in hemibiotrophic plant pathogens, we observe that the losses of metabolic enzymes in obligate biotrophs are not random and that gene losses predominantly influence the terminal branches of the metabolic networks. Our analyses represent the first metabolism-focused comparison of oomycetes at this scale and will contribute to a better understanding of the evolution of oomycete metabolism in relation to lifestyle adaptation. Numerous oomycete species are devastating plant pathogens that cause major damage in crops and natural ecosystems. Their interactions with hosts are shaped by strong selection, but how selection affects adaptation of the primary metabolism to a pathogenic lifestyle is not yet well established. By pan-genome and metabolic network analyses of distantly related oomycete pathogens and their nonpathogenic relatives, we reveal considerable lifestyle- and lineage-specific adaptations. This study contributes to a better understanding of metabolic adaptations in pathogenic oomycetes in relation to lifestyle, host, and environment, and the findings will help in pinpointing potential targets for disease control. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.