Plant, Cell & Environment最新文献

Irradiance strongly affects the morphology, carbon (C) uptake and construction costs of leaves and branches. Within tree crowns, light decreases from the top downwards, but whether this translates to differences in the C balance of sun and shade branches remains unclear. Here, we combined a light-driven photosynthesis model, parameterised with empirical data, with functional growth analyses to estimate the C costs and amortisation times of upper, sun exposed and lower, shaded branches in the crowns of mature trees from nine European species in a diverse and relatively open mixed forest. Amortisation times for the C costs of 1-year-old branches varied among species, but not between sun and shade branches except for two species. Expressed as percentage of the branch C uptake, branch costs were similar between crown positions in most species. Finally, a similar proportion of C assimilation is used for the seasonal build-up of starch in upper and lower branches. Our results show that, at least in forests with relatively open canopies as the one studied here, the balance of assimilation and structural and non-structural C costs at the branch-level is finely tuned along the light gradient, suggesting a high degree of C autonomy even in shaded branches.

Plants under stress emit volatile organic compounds (VOCs) that can influence neighbouring plants. While most studies have focused on the role of VOCs priming the fitness of neighbouring plants, their involvement in priming bioactive compound accumulation in herbal plants remains less clear. In this study, we treated Scutellaria baicalensis Georgi using copper solution, identified the VOCs emitted from S. baicalensis and VOCs accumulated internally in tissues, and quantified total flavonoid and major bioactive compounds. We found that copper treatment inhibited the emissions of acetic acid butyl ester, cyclopentanone and ethyl 2-methylpropanoate. Concurrently, it significantly increased internal levels of 2-propanone and 3-methyl-3-buten-1-ol in aerial parts of both copper-treated (COT) and cocultured untreated (COU) seedlings, alongside a marked decrease in ethanol in COT. In underground parts, the 2-ethyl-1-hexanol and methoxybenzene only presented in COT, the 1-hexanol, 2-acetylfuran and n-pentanal exhibited higher accumulation in both COT and COU. Moreover, copper also enhanced total flavonoid content in COT and, notably, in COU, indicating a priming effect. Individual flavonoids showed a nuanced fluctuation in the aerial parts, but a general decrease in the underground parts. Together, our findings indicate that copper-induced airborne cues, dominated by VOCs, prime neighbouring plants to reconfigure phytochemical profiles, with consequences for herbal quality via shifts in bioactive compound composition.

Caucasian clover (Trifolium ambiguum M. Bieb.) is a valuable perennial legume with a robust root system. HECT-type E3 ubiquitin ligases (UPLs) are known regulators of plant growth, but their functions in root development, particularly in forage legumes, remain largely unexplored. Here, we identified 32 TaUPL genes in Caucasian clover and found that TaUPL21 is highly expressed in rhizome buds. Overexpression of TaUPL21 significantly enhanced root growth, including increases in root length, volume, and tip number. Strikingly, DNA affinity purification sequencing (DAP-Seq) revealed an unexpected DNA-binding capacity of TaUPL21. We further identified the MADS-box transcription factor TaAGL29 as a direct downstream target. Yeast one-hybrid (Y1H) and dual-luciferase (d-Luc) assays confirmed that TaUPL21 directly binds to the promoter of TaAGL29 and functions as a transcriptional activator. Our results unveil a novel, non-canonical function for a HECT E3 ubiquitin ligase, providing fresh insights into the functional versatility of E3 ubiquitin ligases and present a valuable genetic resource for improving root architecture in plants.

Plants have evolved highly efficient strategies to maintain iron (Fe) homeostasis. In this study, we investigate the impact of arbuscular mycorrhizal (AM) symbiosis on the Fe-deficiency response and ionomic profile of tomato plants, as well as how Fe availability affects AM symbiosis. Fe deficiency and AM colonization both reduced shoot Fe concentrations, while root Fe concentrations increased in AM plants. Notably, Fe accumulated in cortical cells colonized by arbuscules. We further show that Fe deficiency reduces expression of AM-related tomato genes (SlEXO84, SlRAM1, SlAMT2.2 and SlPT4) and of the fungal RiEF1α gene. These findings indicate that Fe availability is crucial for sustaining AM colonization and symbiotic functionality. Under Fe-limiting conditions, AM symbiosis enhances the Strategy I Fe acquisition pathway (SlFRO1, SlIRT1), an effect not observed under Fe-sufficient conditions. Four vacuolar transporter genes of the VIT/VTL family were identified in the tomato genome. Yeast complementation assays revealed that SlVIT1, SlVTL1, and SlVTL2 function as dual Fe/Mn transporters, whereas SlVIT2 appears to function as a Mn transporter. The high Fe demand of AM symbiosis is supported by the reduced expression of SlVIT1 and SlVTL1 in mycorrhizal roots. Ionomic analysis shows that AM colonization partially alleviates Fe deficiency-induced nutrient imbalances, highlighting its contribution to improved mineral homeostasis under Fe stress.

Plant-positive single-stranded RNA viruses induce vesicles that are crucial for viral infection, replication and spread. However, the mechanisms underlying the vesicle biogenesis induced by negative single-stranded RNA viruses remain largely unknown. Here, a negative single-stranded RNA virus, tomato spotted wilt orthotospovirus (TSWV) which is a representative member of genus Orthotospovirus in the Tospoviridae family, was used as a model to investigate the mechanisms involving the interaction between the viral and the host plant proteins in vesicle formation and function. We found that the nonstructural protein (NSm) of TSWV, could induce endoplasmic reticulum (ER)-derived pathological vesicle biogenesis. In addition, NSm might hijack the host immunity proteins, NtPOX1 (a peroxidase) and pathogenesis-related protein NtPR-4A, to form a potential tetrameric protein complex with Sar1 (a small GTPase), which was crucial for NSm-induced vesicle biogenesis. The results also showed that these ER-derived pathological vesicles provided sites for TSWV replication. These findings provide novel and robust insights for understanding the infection processes and mechanisms of plant-negative single-stranded RNA viruses.

N⁶-methyladenosine (m⁶A) is the most prevalent epitranscriptomic modification found in eukaryotic mRNA. The levels of m⁶A are determined by the coordinated actions of methyltransferases ('writers') and demethylases ('erasers') that introduce and remove m⁶A marks, respectively. Recent studies have demonstrated that chloroplast mRNAs are highly rich in m⁶A; however, the significance of m⁶A methylation in chloroplasts remains unknown. As no mRNA m⁶A writers and erasers have been identified in chloroplasts, in this study, we artificially imported ALKBH10B, a well-characterised mRNA m⁶A eraser localised in the nucleus and cytoplasm in Arabidopsis (Arabidopsis thaliana), into chloroplasts to uncover the potential impact of m⁶A modification in chloroplasts on photosynthesis and abiotic stress response. We found that the chloroplast-targeted ALKBH10B successfully removes m⁶A marks from numerous mRNAs in chloroplasts. Notably, the ALKBH10B-mediated demethylation f m⁶A marks in chloroplast mRNAs enhanced salt and drought tolerance in Arabidopsis by modulating the stability of m⁶A-modified photosynthesis-associated mRNAs. Overall, our findings reveal that ALKBH10B-mediated m⁶A demethylation in chloroplast mRNAs enhances photosynthesis and stress tolerance, highlighting that modulation of RNA methylation in chloroplasts can be a potential means for breeding stress-tolerant plants.

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.