Plant, Cell & Environment最新文献

Through long-term natural selection, a co-evolutionary relationship has formed between plants and pests. However, pathogens and pests can also undermine plant resistance by releasing certain substances such as effectors. Helicoverpa armigera R-like protein 1 (HARP1), an effector in oral secretions, is capable of interacting with JASMONATE-ZIM DOMAIN (JAZ) protein. This interaction inhibits the degradation of JAZ and prevents the activation of jasmonic acid (JA) signalling in response to biotic stress. Nevertheless, the mechanism by which HARP1 interacts with JAZ to suppress JA signalling remains elusive. In this study, we first confirm that the ZIM domain within JAZ is sufficient for the HARP1-JAZ interaction. To gain mechanistic insight, we determined the crystal structure of HARP1 and utilised AlphaFold2 to predict its binding mode with JAZ3. The structure analysis reveals that HARP1 is a β-sandwich fold composed of seven strands, which directly binds to JAZ homo- or hetero-dimers. This binding prevents the degradation of the JAZ repressor, consequently ensuring the repressed JA signalling pathway in the plant. Our structural and functional studies provide new insights into the JA signalling transcriptional repression mechanism by effectors released by pests that suppress JA signalling.

Wheat production is threatened by many destructive diseases, particularly Fusarium crown rot (FCR) and Fusarium head blight (FHB), for which effective control strategies are urgently needed. Here, we systematically screened 28 Clonostachys spp. strains for biocontrol efficacy against FCR and identified Clonostachys chloroleuca strain Cc620 as a highly promising agent. Cc620 exhibited strong mycoparasitic activity against Fusarium pathogens and functioned as an endophyte primarily colonizing wheat roots. Seed treatment with Cc620 significantly promoted wheat seed germination, root development, and enhanced resistance to both FCR and FHB under greenhouse and multi-location field conditions. Furthermore, the Cc620 application improved agronomic traits of wheat in fields and suppressed a broad spectrum of wheat and soybean diseases. Genomic and transcriptomic analyses revealed that Cc620 induces extensive metabolic reprogramming and upregulates defense-related pathways in wheat, including key immune regulators such as TaWRKY33. Moderate overexpression of TaWRKY33 in wheat conferred increased resistance to both FCR and FHB without a yield penalty. Field surveys confirmed the natural occurrence and strong colonization potential of C. chloroleuca in major wheat-growing regions. Our findings demonstrate that Cc620 is a robust and sustainable biocontrol agent, offering a promising alternative for integrated disease management in wheat production.

Brassica oleracea exhibits remarkable morphological diversity and is cultivated worldwide. We previously showed that dense trichomes in a wild accession (B. incana, C01) confer resistance to insect pests, yet the underlying regulatory mechanisms remain unclear. Here, we developed a cleaved amplified polymorphic site (CAPS) marker to distinguish sequence variations in BolTRY-l between trichome-rich C01 and glabrous C41. Functional analyses revealed that overexpression of BolTRY-l in the Arabidopsis try mutant and in C01 markedly suppressed trichome initiation, identifying BolTRY-l as a negative regulator. Promoter sequence comparison and activity assays further indicated that divergence in the BolTRY-l promoter underlies the contrasting trichome phenotypes between C01 and C41. Using the HDOCK server, yeast one-hybrid (Y1H), and dual-luciferase reporter (Dual-LUC) assays, we showed that BolMYB34-l directly binds to MYB-binding site (MBS) elements within the BolTRY-l promoter in C01. In addition, co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFC), and luciferase complementation (LCA) assays confirmed a physical interaction between BolMYB34-l and BolTRY-l. Overexpression and virus-induced gene silencing (VIGS) analyses further supported that BolMYB34-l functions as an upstream negative regulator of BolTRY-l. Collectively, our findings reveal a novel regulatory module in which the BolMYB34-l-BolTRY-l complex negatively regulates trichome formation in B. oleracea.

Bacterial diseases pose a serious threat to horticultural crops, necessitating the exploration of biocontrol resources for sustainable agricultural development. This study characterises Burkholderia arboris M13, a novel biocontrol strain exhibiting broad-spectrum antagonism in vitro against major phytopathogenic bacteria of horticultural crops, including Pseudomonas syringae pv. tomato, Ralstonia solanacearum, Paracidovorax citrulli, and Xanthomonas campestris pv. campestris. Applications of its bacterial suspension or culture supernatant significantly suppressed tomato bacterial speck, bacterial wilt, watermelon bacterial fruit blotch, and cabbage black rot in greenhouse and field trials. The strain also induced plant systemic resistance and promoted plant growth. Genomic analysis revealed significant novelty, as B. arboris M13 possesses two unique plasmids and harbours 20 biosynthetic gene clusters for secondary metabolites, with several showing weak collinearity to close relatives, indicating genetic determinants for its expanded functionality. Furthermore, B. arboris M13 demonstrated compatibility with the plant growth regulator (24-epibrassinolide) but incompatibility with the copper-based bactericide copper hydroxide, which enhances its practical integration into existing crop management strategies. This combination of effective biocontrol, plant growth promotion, distinct genomic features, and chemical compatibility establishes B. arboris M13 as a versatile and promising candidate for sustainable agriculture.

RNA quality control pathways, particularly nonsense-mediated mRNA decay (NMD), function as critical antiviral defenses by degrading aberrant viral transcripts. However, how DNA geminiviruses counteract this RNA surveillance system remains largely unknown. Here we report that the Sri Lankan cassava mosaic virus (SLCMV) AC4 protein employs a novel strategy to suppress NMD: it targets the central regulator Upf1 for degradation. In Nicotiana benthamiana and Arabidopsis thaliana models, we demonstrate that SLCMV AC4 directly binds AtUpf1 via its N-terminal domain and triggers its depletion through the coordinated action of both the autophagy and ubiquitin-proteasome pathways. AC4 expression stabilized a broad range of endogenous NMD substrates and enhanced the accumulation and pathogenicity of a heterologous virus. Structural and functional analyses revealed that the N-terminal myristoylation motif of AC4 is indispensable for its function. While point mutations within this motif preserved Upf1 binding, they abrogated NMD suppression and Upf1 degradation, indicating the motif's essential role in assembling a functional degradation complex beyond mere interaction. Furthermore, we elucidate that AC4 activates autophagy by competitively disrupting the GAPC2-ATG3 interaction, thereby liberating ATG3 to promote autophagosome formation. Our findings unveil a sophisticated viral counter-defense mechanism in which a pathogen effector orchestrates the spatially coordinated degradation of a key host RNA surveillance factor, bridging the fields of plant-virus interactions, RNA biology, and host proteostasis.

Concerns about biotic stress in agriculture have recently increased with the emergence of persistent pathogens and pests. N⁶-methyladenosine (m⁶A) RNA is a conserved epitranscriptomic modification. Recent advances in plant biotechnology and m⁶A profiling have generated unprecedented knowledge. Our review emphasizes recent state-of-the-art reports regarding m⁶A modulation of plant responses to biotic stress. We found that m⁶A modification plays a "master rheostat" role in plant immunity, potentially integrating signaling, transcription, protein turnover, and global metabolic pathways to achieve vigorous, as well as balanced, responses to biotic stress. This review highlights the potential for m⁶A to dynamically modulate interactions between plant defense hormones and defense pathways. m⁶A modulates the stability and activity of transcription factors, regulates defense proteins, antimicrobial metabolite production, antiviral defense, systemic acquired resistance, and the ubiquitin-proteasome pathway. Our review examines contextual factors that coordinate the activity of m⁶A-associated proteins and modulate global m⁶A dynamics. Importantly, we have addressed m⁶A in the context of promising trade-offs between defense and growth, and in the role of m⁶A-associated proteins in liquid-liquid phase separation to control hormonal transcript levels and fine-tune the plant defense response. Overall, this review proposes a new horizon for developing more biotic-stress-resilient plants.

Salinity stress predominantly affects negatively charged cell wall polymers, for example, pectin. Excess Na⁺ ions interact physically and affect growth in stress-sensitive plants. However, the salinity resistance of sugar beet cell walls remains unclear. To get a better understanding of cell wall assembly, we investigated arabinogalactan-proteins (AGPs), extensins and pectic polysaccharides (homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II), in relation to underlying physiological mechanisms and growth expansion with low and adequate boron (B) under salinity. Findings revealed that salt stress affects AGPs and reduces cross-linking of RG-II, resulting in the softening of the sugar beet plant's cell wall. Adequate B compensates for plant growth by improving water flow into the cell, as indicated by the transpiration rate and stomatal conductance. In particular, the higher reduction of the Na⁺/Ca²⁺ ratio in the young leaves and apoplastic fluids and higher RG-I content and dimeric RG-II pectin (a key component of cell wall integrity) offered by adequate B, hint at protection against cell wall defects. However, no influence of B was detected for AGPs and extensins. This suggests that adequate B rescues cell wall integrity, thereby conferring strengthening and acid growth.