Molecular Plant-microbe Interactions最新文献

Phytophthora root rot (PRR), caused by Phytophthora cinnamomi, is one of the most devastating avocado diseases worldwide. We previously reported a group of genetically distinct, more virulent, and less fungicide-sensitive isolates corresponding to the A2 clade II clonal population in southern avocado-growing regions in California that may have originated from Mexico. To test this hypothesis, we assessed the genetic and phenotypic diversity of the California and Mexico avocado P. cinnamomi populations. We found that P. cinnamomi populations in these two locations belong to the two previously described A2 clades. Higher genetic differentiation was detected among Mexican isolates when compared with the populations from California; however, most Mexican isolates clustered with the California A2 clade II populations, providing evidence for the Mexican origin of these isolates in southern avocado-growing regions. With the exception of one diploid Mexican isolate, all isolates were estimated to be triploid based on inferred allele ratios. Despite clonality, wide phenotypic variability was detected within and among populations regarding growth rate, optimal growth temperature, fungicide sensitivity, and virulence. Interestingly, contrasting virulence patterns were found depending on the host and infected tissue utilized. This study reveals the adaptative capacity of clonal P. cinnamomi populations to local environments and control methods. Pathogen migration between Mexico and California was also inferred, which highlights a pathway that should be surveilled if further emergence is to be avoided. Monitoring and characterizing the P. cinnamomi populations is critical to developing effective and durable PRR control methods to ensure the sustainability of the avocado industry worldwide. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Grapevine red blotch virus (GRBV), a member of the Geminiviridae family that causes reduced fruit quality and yield, is an emerging challenge for the wine industry. Viticultural practices and pest management have been largely ineffective at mitigating the impacts of GRBV, necessitating alternative control strategies. Here, we investigated the early activation of RNA interference (RNAi) in GRBV-infected grapevines and, through small RNA sequencing, identified nine genomic virus-derived small-interfering RNA (vsiRNA)-producing regions referred to as hotspots (HSs). Subsequent analyses revealed that these HSs were primarily involved in producing 24-nt vsiRNA species associated with transcriptional gene silencing toward later stages of infection. Double-stranded RNA molecules derived from these HSs were administered to GRBV-infected plants via root soaking, significantly (P < 0.05) reducing viral gene expression in leaves and petioles for up to 1 month. Ultimately, we assessed the potential of viral mutation within these HSs, identified areas of higher mutational entropy, and found that most HS locations are within viral regions with lower probabilities of mutation events. These findings provide the basis for future research to characterize the role of small RNA-induced silencing mechanisms in grapevine-GRBV interactions and their potential translation for field-based technology, such as RNAi biopesticides, to manage red blotch disease. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Intensive spinach cultivation creates favorable conditions for the emergence and rapid evolution of pathogens, leading to substantial economic losses. Research on host-pathogen interactions in leafy greens would benefit from advanced biotechnological tools; however, the absence of such tools in spinach hampers our understanding of spinach immunity. Here, we explored the potential of type III secretion system (T3SS)-mediated effector delivery to study pathogen effector activity in spinach. We identified the Pseudomonas syringae pv. tomato DC3000 (DC3000) polymutant D36E, which lacks 36 known T3SS effectors (T3Es), as a promising T3SS-dependent effector delivery system for spinach. Unlike DC3000, which causes necrotic symptoms on spinach and reaches high bacterial titers, D36E did not proliferate and caused no visible symptoms. Using D36E, we screened 28 DC3000 T3Es in spinach, assessing symptom development, bacterial proliferation, and reactive oxygen species (ROS) bursts as a proxy for early immune responses. AvrE1 and HopM1 emerged as key determinants of DC3000-like infection, inducing water-soaked lesions, whereas HopAD1 strongly suppressed ROS production. Our findings establish the D36E-based effector delivery system as a powerful tool for high-throughput effector studies in spinach. It bridges the gap between genomics-based effector predictions and experimental validation, paving the way for knowledge-driven resistance breeding in non-model crops such as spinach. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

In the environment, multiple microbes can interact with each other in the plant phyllosphere. These associations can shape the plant's development, stress responses, and disease susceptibility, but the molecular mechanisms that govern this process remain unexplained. Of interest are the multiple or successive infections that crop plants are exposed to within a growing season. One of the most common and economically important viruses of potato is potato virus Y (PVY, Potyviridae). We show that PVY infection of potato limited the expansion of foliar necrotic lesions caused by the early blight fungus Alternaria solani. The reduced growth phenotype persisted when the fungal mycelium was transferred to solid growth media. RNA-seq analysis of responses in potato and A. solani to the presence of PVY suggested two mechanisms that can explain this interaction. First, in A. solani exposed to PVY-positive leaves, we observed a downregulation of fungal pathogenicity genes. Second, we found that, in the absence of PVY, A. solani downregulates ethylene-responsive defense in potato, but this effect was eliminated when the host was infected with PVY. Our findings expand our understanding of how pathogen virulence can be affected by other pathogens competing for the same host resources. The observation that PVY can alter A. solani infection illustrates the ecological role of viruses as a potential contributor to the development of disease outbreaks. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Plants are sessile organisms and must accurately respond to a variety of growth, developmental, and environmental signals throughout their life to maximize fitness. Plant cell surface receptor-like kinases are ideal for the perception of such signals and their transduction within the cell. The Strubbelig receptor family (SRF) is a group of leucine-rich repeat receptor-like kinases, several of which have unknown function. Here, we identify a role for SRF6 in the perception of cell wall damage and the activation of downstream immune responses. We show that SRF6 is necessary for proper immune responses following elicitation with a short-chain oligogalacturonic acid, including activation of defense genes and increased bacterial resistance. We also demonstrate that the srf6 mutants are more sensitive to isoxaben treatment, suggesting enhanced cell wall integrity maintenance responses. These findings are compatible with the hypothesis that cell wall integrity maintenance responses are elevated when pattern-triggered immunity is compromised. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Cyst nematodes establish a highly specialized feeding structure called a syncytium in host roots by secreting effectors into a selected host cell that reprogram host development programs. The selected host cell undergoes distinct morphological, physiological, and gene expression changes, resulting in the fusion of hundreds of cells to create a novel cell type that does not normally exist in the host. Here, we profiled the transcriptome of the syncytium induced by the beet cyst nematode (BCN) Heterodera schachtii in Arabidopsis roots using laser capture microdissection and RNA sequencing. Aside from biological processes that are expected to be altered by nematode infection, we also found that genes annotated in nitrate and iron ion signaling and transport-related biological processes are significantly overrepresented in genes that are downregulated by BCN infection, suggesting that these ions may play important roles in BCN infection. Comparing the syncytium transcriptome with that of various root cell types showed that it was overrepresented by genes that are enriched in cells marked by ATHB15, a member of the HD-ZIP III transcription factor family that is highly expressed in the stem cell organizer of the root vasculature. These results suggest that the syncytium may partially adopt the molecular signature of a stem cell organizer, consistent with our previous hypothesis that BCN uses a stem cell organizer as an intermediate status for syncytium formation. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Potato powdery scab, caused by the soilborne pathogen Spongospora subterranea f. sp. subterranea (Sss), poses a significant threat to potato production, reducing potato value and impacting fresh market quality. Effective management strategies for this disease are currently lacking, and Sss is widespread in many potato-growing regions, highlighting the urgent need for effective control measures. Although the use of disease-resistant cultivars holds potential as a sustainable solution, the genetic mechanisms underlying resistance to Sss remain unclear. In this study, we investigated the role of the defense-related phytohormone salicylic acid (SA) in potato resistance to Sss. Initial analyses of defense gene expression revealed transcriptional reprogramming in response to Sss infection in potato hairy root cultures. Quantification of defense-related phytohormones further demonstrated a significant increase in SA levels in Sss-infected roots, whereas other phytohormones, jasmonic acid and ethylene, showed no substantial variation. Pretreatment of hairy roots with SA resulted in a marked reduction in Sss propagation, suggesting that SA contributes to induced resistance against the pathogen. To further elucidate the role of SA, we utilized transgenic potato hairy roots overexpressing the tomato SA receptor gene SlNPR1 to enhance SA sensitivity or expressing the bacterial nahG gene to deplete endogenous SA. Our findings showed reduced Sss growth in SlNPR1 overexpression lines, whereas nahG lines exhibited increased pathogen proliferation. These findings were further validated in fully grown potato plants using a pot assay. Collectively, our results indicate that SA plays a pivotal role in mediating resistance to powdery scab in potato. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The necrotrophic pathogen Alternaria alternata produces a host-selective toxin to attack its host plants. This study characterized the crucial function of the Mip1/RAPTOR ortholog (AaMip1) in toxin production and autophagy formation. AaMip1 physically interacts with the Target of Rapamycin (Tor) protein. In response to nitrogen starvation and hydrogen peroxide (H₂O₂), AaMip1 binds to Tor and triggers autophagy and oxidative stress detoxification. Deleting the AaMip1 gene resulted in a ΔAaMip1 strain that increased sensitivity to various oxidants; decreased the expression of two oxidative-stress-response genes, AaYap1 and AaNoxA; and had lower catalase activity than the wild type. ΔAaMip1 produced lower levels of ACT toxin than the wild type after a 7-day incubation; however, ΔAaMip1 produced tricycloalternarene mycotoxins but not ACT after 21 days. The reduction of ΔAaMip1 virulence in the host plant is due to low ACT production, defective H₂O₂ detoxification, impaired autophagy, and slow growth during invasion. However, AaMip1 plays a negative role in maintaining cell wall integrity and lipid body accumulation. ΔAaMip1 had thicker cell walls and emitted brighter red fluorescence after staining with the cell-wall-disrupting agents Congo red and calcofluor white. ΔAaMip1 was more resistant to these compounds than the wild type under nutrient-rich conditions. The observed defects in the ΔAaMip1 were restored in the complementation strain after re-expressing a functional copy of AaMip1. This study increases our understanding of how A. alternata deals with toxic reactive oxygen species, triggers autophagy formation, maintains normal cell wall integrity, and regulates toxin metabolism via the AaMip1-mediated signaling pathways. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.