New Phytologist最新文献

Land plants follow an evolutionary trajectory of 'gametophyte reduction' and 'sporophyte dominance'. As a major shift in gametophyte reduction, gymnosperms have evolved a unique female gametophyte (FG) development mode, associated with their prolonged reproductive cycles. However, the genetic programs underlying this process remain largely unknown. Here, we employed anatomical, transcriptomic, and genetic approaches to investigate the female gametogenesis, focusing on the divergent coenocytic free nuclear stage in three species (Cedrus deodara, Picea smithiana, and Pinus tabuliformis) from the largest gymnosperm family Pinaceae. We obtained a comprehensive anatomical profile of FG development, correlating variations in the timing of the free nuclear stage with the diverse reproductive cycles. We also revealed the transcriptional dynamics underlying each stereotypical stage of FG development, highlighting the involvement of cyclin-dependent kinase 2a, cyclin B genes, specific MADS-box genes, and other conserved homologous transcription factors. Moreover, a focused examination of the fascinating long reproductive cycle of Pinus, the largest genus of gymnosperms, further unveiled regulatory molecules for growth-defense trade-off and summer dormancy of FG. Our study highlights the molecular mechanisms underpinning heterochronic development of FG during the free nuclear stage in Pinaceae, offering crucial insights into the evolution of plant reproductive strategies.

High concentrations of manganese (Mn) ions in the soil of facility-based cultivation significantly restrict the development of the cucumber industry. However, the genetic mechanisms governing Mn accumulation in crops are still not well comprehended. Through the comprehensive integration of molecular biology, epigenetic modification analysis combined with genetic analysis, we functionally characterized a novel regulatory module. Consisting of a long non-coding RNA (lncRNA, asCsMTP6) and its mitochondria-localized target Metal Tolerance Protein 6 (MTP6), it coordinately regulates Mn accumulation in cucumber. CRISPR-CsMTP6 or asCsMTP6-OE mimics toxicity, whereas CsMTP6-OE or asCsMTP6 knockdown enhances tolerance, confirming that asCsMTP6 negatively regulates CsMTP6 transcription. Additionally, the H3K27me3 methylation marks surrounding the CsMTP6 genome are reduced under Mn stress, and the inhibited expression of asCsMTP6 results in a lower level of H3K27me3 methylation in the CsMTP6 gene body and 3'UTR region, thereby facilitating the expression of CsMTP6 for tolerance to Mn stress. Furthermore, virus-induced silencing of histone methyltransferases SWN and CLF also reduces H3K27me3 methylation in the CsMTP6 genomic region, thus releasing the expression of CsMTP6. Taken together, this study demonstrates the epigenetic regulation of lncRNAs in response to Mn stress, providing new insights into the potential for developing cucumber varieties with improved tolerance to manganese-contaminated soils.

Wind-driven plant movement generates rapid light fluctuations (windflecks), which can impact canopy photosynthesis. Targeting crop photosynthesis in dynamic light provides a potential path towards boosting yield. Here, we quantified how plant architecture and biomechanics modulate such windflecks across 10 high-yielding cultivars of winter wheat (Triticum aestivum). Using synchronized high-frequency measurements of irradiance, wind speed, and canopy motion (quantified by frame differencing from video), we assessed the propensity of wheat cultivars to move (motion sensitivity), and the ability for movement to produce windflecks (light modulation efficiency) in the field. There was up to 10-fold variation in the quantity of motion between cultivars under identical wind speeds. Cultivars also exhibited structural trade-offs and specific in canopy windfleck properties. Some had low motion under wind but produced frequent windflecks when moving, whereas others exhibited high motion under similar wind but varied in windfleck frequency. Overall, windfleck properties were best explained by aerodynamic traits: cultivars with narrower leaves and lower leaf-to-stem mass ratios were associated with more intense windflecks. These findings establish that wheat cultivars actively modulate their light environment through biomechanical traits. By integrating plant motion into crop models, favouring motion-light relationships, which could provide a critical route to yield improvements in turbulent environments.

Fairy rings in grasslands formed by basidiomycetes fungi are characterized by a green belt with luxuriant plants and soil nutrients. However, the way in which the fairy ring fungi enhance plant-available nutrients and subsequently influence plant growth remains poorly understood. We conducted an observational study involving 30 fairy rings in alpine grasslands to investigate the effects of fairy ring fungi on plant biomass, available nutrients, and soil microbial functions. Furthermore, a glasshouse experiment was performed to test the differential response of five plant species to increased ammonium nitrogen (NH₄ ⁺-N) induced by fairy ring fungi. We found that fairy ring fungi enhanced soil NH₄ ⁺-N accumulation, which might be due to increases in the relative abundance of specific bacteria and N-acquiring enzyme activities. Meanwhile, fairy ring fungi increased the abundance of genes related to N fixation and mineralization, but decreased the abundance of a nitrification gene. Furthermore, the observed 82% greater shoot biomass on the fairy ring as compared to outside it was mainly attributed to grasses and sedges, which were promoted by the increased NH₄ ⁺-N concentration. Our findings reveal a novel mechanism by which fairy ring fungi stimulate the microbial capacity to convert available nutrients, thereby reshaping plant composition in alpine grasslands.

Heat shock proteins (HSPs) are evolutionarily conserved, yet their functions in plant growth and development remain incompletely characterized. Here, we demonstrate that a HSP90 co-chaperone PpNudC6 is essential for directional cell expansion in the moss Physcomitrium patens. We generated ppnudc6 mutants and characterized their phenotypes. Dysregulation of PpNudC6 disrupts cellulose microfibril organization and cell wall stiffness gradients, as shown by scanning electron microscopy and atomic force microscopy, ultimately resulting in shortened and thickened protonemal cells. Mechanistically, this phenotype is mediated by disrupted reactive oxygen species (ROS) homeostasis. Loss of PpNudC6 function induces ectopic activity of the NADPH oxidase PpRbohD in protonemata, leading to abnormal ROS accumulation. Pharmacological inhibition of NADPH oxidases by diphenyleneiodonium rescues mutant phenotypes, confirming ROS overproduction as the primary driver of developmental defects. Furthermore, PpNudC6 interacts with the scaffold protein PpRACK1B and the co-chaperone PpSGT1, suggesting a multisubunit complex that modulates respiratory burst oxidase homolog (Rboh) activity. In summary, our findings reveal a chaperone-mediated regulatory module that mediates the production of ROS, thereby maintaining cell wall mechanical anisotropy required for directional expansion. This work provides insights into a novel role of HSP complexes in regulating directional cell expansion and links redox homeostasis to cell wall mechanics during moss development.

Plant-biotic interactions are driven by the exchange of molecules. Small peptide hormones like CLAVATA3/EMBRYO SURROUNDING REGION (CLE) peptides play central regulatory roles in these interactions. CLEs determine the extent of symbiotic interaction to balance costs and benefits for the host. In parasitic interactions, CLEs regulate the formation of feeding sites by plant pathogenic nematodes and promote the formation of haustoria in parasitic plants. By reviewing recent findings on CLE functions, their receptors, and responses across different biotic interactions, we provide insights into the increasingly complex roles of CLEs in plant development and nutrient signaling.

How long do fungal hyphae persist in the environment? And how does this differ between groups and species of fungi? Despite growing knowledge of fungal contributions to decomposition and soil carbon cycles, surprisingly little is known about the turnover of mycelia: What happens to fungal hyphae over time? And how this impacts different fungi's contribution to carbon sequestration? In this study, we compared microscale persistence of fungal hyphae using microfluidic chip technology and visual quantification of hyphal degradation and turnover across six different wood-decay Basidiomycete species. Measured traits included hyphal extension, coverage, turnover rates, and changes in hyphal morphology over time when supplied with two carbon sources of differing recalcitrance. Species clustered into two groups: one with a frugal nutrient strategy (high turnover capacity, active persistence of cytoplasmic hyphae) and one with a wasteful strategy (low turnover of hyphae and large remnants of skeletonized hyphae). Differences matched the ephemeral or long-lasting nature of their fruiting bodies and the substrates they inhabit. Carbon type also influenced hyphal persistence over time. Our results suggest that hyphal turnover has a genetic basis linked to species ecology yet is also shaped by environmental factors such as carbon availability, highlighting the dynamic nature of fungal mycelia.

The Chrysanthemum genus (Asteraceae) is a key polyploidy model, but its complex genomes obscure its origin and evolution. To address this, we developed chromosome-set-specific painting probes from the Chrysanthemum morifolium 'Zhongshanzigui' haploid genome, enabling precise identification of all nine chromosome sets. Combined with existing oligonucleotide probes (Oligo-Mix: CmOP-1 and CmOP-2), we established a novel sequential fluorescence in situ hybridization (FISH) procedure for comparative genomic analysis. Applying this across six Chrysanthemum species revealed extraordinarily conserved chromosomal synteny. Analysis of diploids (e.g. C. nankingense, C. lavandulifolium, and C. indicum) and their derived autotetraploids showed autopolyploidization involved amplification of large-scale repetitive sequences and loss of partial repeats. Crucially, rapid cytological diploidization (diploid-like bivalent pairing) occurred, associated with significant enrichment of repetitive sequences at meiotic crossover (CO) loci on homologous chromosomes. This leads us to hypothesize that repetitive DNA variation may facilitate precise chromosome segregation and diploid-like meiosis, thereby potentially ensuring polyploid stability. These findings provide essential tools for distinguishing homologous chromosomes and significant potential for elucidating homologous interactions to advance polyploid Chrysanthemum breeding.