Plant, Cell & Environment最新文献

Plant roots can detect and react to the presence of competitors' roots. Intraspecific competition usually constrains root proliferation to minimize the overlap of root systems between competitors, especially in resource-impoverished environments. However, it remains largely unclear whether and how this decline in root nutrient-scavenging capacity can be complemented by other nutrient-acquisition strategies. Here, we leveraged 25 of 41-year-old Pinus Sylvestris var. mongolica monocultures with stand densities ranging from 350 to 1500 trees per hectare, reflecting a gradient of intraspecific competition intensity. In these stands, we measured variables of ecosystem nitrogen (N) status, needle N resorption efficiency, and nine root morphological, physiological and mycorrhizal traits. Results showed that increasing stand densities decreased soil N transformation rates and carbon-:N-acquisition enzyme ratios, indicating an increasing degree of N deficiency. High-density stands had lower root length density than low-density stands, implying intense intraspecific competition causing root segregation. Conversely, stand density was positively correlated with the relative abundance of ectomycorrhizal fungi (EMF) with genetic potential to produce class II peroxidases. Collectively, these findings highlight that the decline of plant-available soil N may account for root segregation under intraspecific competition and suggest the complementarity of fine roots and EMF in nutrient acquisition at the intraspecific level.

Light plays a pivotal role as an environmental factor throughout the entire life cycle of plants, influencing plant growth, development, stress responses, and specialised metabolism. In this study, we identified six growth regulating factors (GRFs) in Catharanthus roseus through genome sequence analysis, and notably, two GRFs, CrGRF1 and CrGRF4, exhibited responsiveness to light signals. By manipulating the expression of CrGRF1 and CrGRF4 in C. roseus leaves, both through overexpression and silencing, we observed their capacity to enhance the accumulation of monoterpenoid indole alkaloids (MIAs) by upregulating the expression of 10-hydroxygeraniol oxidoreductatse (Cr10HGO) and 7-deoxyloganetic acid synthase (Cr7DLS). Furthermore, yeast one-hybrid and dual-luciferase reporter assays confirmed that CrGRF1 and CrGRF4 directly activate Cr10HGO expression by binding to the TFmatrixID_0441 cis-elements (ctTTCAGa) within its promoter region. This study sheds new light on the crucial role played by the growth regulating factor (GRF) gene family in regulating specialised metabolic pathways in plants. Elucidating the roles of CrGRF1 and CrGRF4 lays an essential foundation for future research to decipher the molecular mechanisms governing light-controlled MIA production in C. roseus.

Somatic embryogenesis (SE) is a powerful biotechnological tool widely utilized for large-scale propagation and genetic transformation. Morphogenic genes like BABY BOOM (BBM) and WUSCHEL (WUS) play crucial roles in SE and are extensively applied to improve SE-based genetic transformation. However, the transcriptome profiling and key regulatory factors of SE in the woody magnoliid Liriodendron hybrid remain unclear. Here, we depicted the time-series transcriptome profiling of SE in Liriodendron hybrid, highlighting the temporal significance of morphogenic genes like BBM in embryogenic callus and developing somatic embryos. Expression patterns were validated using qRT-PCR and transgenic lines expressing β-glucuronidase (GUS) and red fluorescent protein mCherry driven by the LhBBM promoter. Overexpression of LhBBM, both constitutive (CaMV 35S promoter) and SE-specific (Liriodendron WOX9 promoter), enhanced SE and embryonic callus induction. Conversely, CRISPR/Cas9-mediated knockout of LhBBM reduces SE efficiency without compromising callus induction. Furthermore, we developed a secondary callus induction method that minimized the heterogeneity of a transgenic callus line, confirming the sufficiency and necessity of LhBBM in SE. Notably, LhBBM significantly improved genetic transformation efficiency in Liriodendron. These findings establish LhBBM as a promising target for enhancing SE capacity and SE-based transformation efficiency, particularly in forest trees.

Virus-induced gene silencing (VIGS) is an attractive reverse genetics tool for gene silencing in difficult to transform plants. Although a few VIGS vectors have been developed for soybean, they were never utilised for functional analysis of nodulation, a critical process for improving sustainable soybean cultivation. This is unfortunate, because several genes regulating this process are expressed in the upper parts of the plant, hence remain understudied due to limitations of the commonly used fast Agrobacterium rhizogenes-mediated hairy root transformation and stable transformation approaches. An instance involves components of the autoregulation of nodulation (AON) pathway controlling the optimal number of nodules through systemic long-distance root-shoot-root signalling pathway. We developed a fast and reliable VIGS protocol based on cowpea severe mosaic virus and used it to examine the roles a selected set of known AON genes in nodulation. We demonstrate the effectiveness of cowpea severe mosaic virus-based VIGS in silencing genes in below- and aboveground tissues and establish VIGS as a valuable tool to study nodulation in soybean.

Plant density significantly impacts photosynthesis, crop growth, and yield, thereby shaping the [CO₂] fertilization effect and intricate physiological interactions in rice. An association panel of 171 rice genotypes was evaluated for physiological and yield-related traits, including the cumulative response index, under both normal planting density (NPD) and low planting density (LPD) conditions. LPD, serving as a proxy for elevated atmospheric [CO₂], significantly increased all trait values, except for harvest index, compared to NPD. A genome-wide association study identified 172 QTNs, including 12 associated with multiple traits under NPD or LPD conditions. Candidate gene mining and network analysis within QTN regions identified potential candidates such as OsHAK1, RGA1, OsalphaCA3, OsalphaCA4, OsalphaCA5, OsCYP38, and OsPIN1, influencing various physiological and yield-related traits under LPD conditions. A significant relationship between the percentage of favorable alleles in genotypes and their performance under different conditions was observed. Potential haplotypes were validated using genotypes identified with contrasting [CO₂] responses, grown under LPD and Free-Air [CO₂] Enrichment facility. These findings can aid in selectively breeding genotypes with favorable alleles or haplotypes to enhance [CO₂] responsiveness in rice. Incorporating greater phenotypic plasticity can help develop climate-smart rice varieties that increase grain yield and quality while mitigating losses from warming temperatures.

Bacteriophages impact soil bacteria through lysis, altering the availability of organic carbon and plant nutrients. However, the magnitude of nutrient uptake by plants from lysed bacteria remains unknown, partly because this process is challenging to investigate in the field. In this study, we extend ecosystem fabrication (EcoFAB 2.0) approaches to study plant-bacteria-phage interactions by comparing the impact of virocell (phage-lysed) and uninfected ¹⁵N-labelled bacterial necromass on plant nitrogen acquisition and rhizosphere exometabolites composition. We show that grass Brachypodium distachyon derives some nitrogen from amino acids in uninfected Pseudomonas putida necromass lysed by sonication but not from virocell necromass. Additionally, the bacterial necromass elicits the formation of rhizosphere exometabolites, some of which (guanosine), alongside tested aromatic acids (p-coumaric and benzoic acid), show bacterium-specific effects on bacteriophage-induced lysis when tested in vitro. The study highlights the dynamic feedback between virocell necromass and plants and suggests that root exudate metabolites can impact bacteriophage infection dynamics.

Potato (Solanum tuberosum L.) is a starch-rich crop with two types of meristematic stems: the shoot and stolon. Shoots grow vertically, while stolons grow horizontally underground and produce tubers at their tips. However, transcriptional differences between shoot and stolon cells remain unclear. To address this, we performed single-cell RNA sequencing of the shoot apex and stolon tip, generating a comprehensive transcriptional landscape. We identified 23 distinct cell clusters with high cell heterogeneity, including cell-specific genes and conserved genes with cell-specific expression patterns. Hormone-related genes, particularly those involved in auxin and gibberellin pathways, exhibited distinct patterns among shoot and stolon cells. Meristematic cells were re-clustered based on the expression of StPOTH15, a homolog of SHOOT MERISTEMLESS (STM) in Arabidopsis. Co-expression networks of transcription factors identified the key transcription factors involved in stolon development. We also constructed developmental trajectories for xylem and phloem development using key vascular genes, including MP, XCP1, PP2A1 and SEOR1. Comparative analysis with Arabidopsis highlighted significant differences in cell type-specific transcript profiles. These results provide insights into the transcriptional divergence between potato shoot and stolon, and identify key transcription factors co-expressed with StPOTH15 that can be used to explore their roles in stolon development.

Symbiotic microbes facilitate rapid adaptation of invasive insects on novel plants via multifaceted function provisions, but little was known on the importance of cross linkages in symbiotic microbiota to insect invasiveness. Novel host pine Pinus tabuliformis is inherently unsuitable for invasive red turpentine beetle (RTB) in China; however, Novosphingobium and Erwinia/Serratia in gallery microbiota (at the interface between RTB larvae and pine phloem) have been discovered to help beetles via biodegrading pine detrimental compounds naringenin and pinitol, respectively. Here, we further revealed significant positive linkage of the two functions, with higher activity level conferring more growth benefit to RTB larvae. Abundance of Erwinia/Serratia was remarkably increased in response to pinitol, while naringenin-biodegrading Novosphingobium was unable to utilize this main phloem carbohydrate directly. High-activity bacterial microbiota produced nutritive metabolites (sucrose and hexadecanoic acid) from pinitol consumption that facilitated growth of both Novosphingobium and beetle larvae. Functional proteins of several bacterial taxa were enriched in high-activity microbiota that appeared to form a metabolic network collectively to regulate the nutrient production. Our results indicate that positive interaction between Erwinia/Serratia and Novosphingobium is critical for RTB invasion success, while Bacilli bacteria might restrict this linkage, providing new insights into symbiotic microbial interactions for insect herbivores.

Mineral nutrients are essential for plant growth, development and crop yield. Under mineral deficient conditions, plants rely on a sophisticated network of signalling pathways to coordinate their molecular, physiological, and morphological responses. Recent research has shown that long-distance signalling pathways play a pivotal role in maintaining mineral homeostasis and optimising growth. This review explores the intricate mechanisms of long-distance signalling under mineral deficiencies, emphasising its importance as a communication network between roots and shoots. Through the vascular tissues, plants transport an array of signalling molecules, including phytohormones, small RNAs, proteins, small peptides, and mobile mRNAs, to mediate systemic responses. Vascular tissues, particularly companion cells, are critical hubs for sensing and relaying mineral deficiency signals, leading to rapid changes in mineral uptake and optimised root morphology. We highlight the roles of key signalling molecules in regulating mineral acquisition and stress adaptation. Advances in molecular tools, including TRAP-Seq, heterografting, and single-cell RNA sequencing, have recently unveiled novel aspects of long-distance signalling and its regulatory components. These insights underscore the essential role of vascular-mediated communication in enabling plants to navigate heterogeneous mineral distribution environments and suggest new avenues for improving crop resilience and mineral use efficiency.

The metabolome, encompassing small molecules within organisms, provides critical insights into physiology, environmental influences, and stress responses. Metabolomics enables comprehensive analysis of plant metabolites, uncovering biomarkers and mechanisms underlying stress adaptation. Regulatory genes such as MYB and WRKY are central to secondary metabolite synthesis and environmental resilience. By integrating metabolomics with genomics, researchers can explore stress-related pathways and advance crop improvement efforts. This review examines metabolomic profiling under stress conditions, emphasizing drought tolerance mechanisms mediated by amino acids and organic acids. Additionally, it highlights the shikimate pathway's pivotal role in synthesizing amino acids and secondary metabolites essential for plant defense. These insights contribute to understanding metabolic networks that drive plant resilience, informing strategies for agricultural sustainability.