New Phytologist最新文献

An extended period of cold exposure enables the process of vernalization in winter cereals and is important for the synchronised timing of the floral transition. The cereal-specific floral repressor VERNALIZATION2 (VRN2) has an integral role in vernalization, yet this locus remains poorly characterised in facultative spring hexaploid wheat, Triticum aestivum. Through the generation of defined germplasm combined with bespoke experimental protocols, which enable a realistic simulation of annual field-based UK growth conditions, we were able to distinguish gene expression and phenotypic differences at the subgenomic level of VRN2 in hexaploid bread wheat. Our research in a facultative wheat suggests that the tandemly duplicated genes comprising the VRN2 locus, ZCCT1 and ZCCT2, have gene expression patterns that respond to multiple environmental factors. These genes also show coregulation, forming a regulatory loop between ZCCT-D1 and ZCCT-D2. The function of these genes beyond the classic vernalization response is explored in a facultative wheat. Here, we identified that VRN-D2 regulates early tiller development, with an accelerated rate of secondary tiller emergence and presence of coleoptile tillers. The findings identify that the VRN2 loci in bread wheat are formed of multiple genes, which have not only overlapping but also unique regulation and function. Selecting these genes individually may offer a route to alter wheat plant architecture without directly impacting vernalization requirement.

Hybridization and polyploidy are major drivers of plant diversification, often accompanied by shifts in gene expression and genome composition. Small RNAs (smRNAs) are thought to influence such genomic changes, particularly through their interactions with transposable elements (TEs). We quantified smRNAs in established sibling allopolyploids Dactylorhiza majalis and D. traunsteineri and their diploid progenitors to assess how independent allopolyploidization events shaped smRNA landscapes. Despite independent origins, the allotetraploids exhibited substantial overlap in smRNA composition, including transgressive accumulation of smRNAs near genes related to transcriptional regulation, cell division, and stress response. Consistently, TE-associated 24 nt smRNAs more closely resembled the paternal and larger genome, while shorter smRNAs typically reflected the maternal and smaller genome. Nevertheless, distinct patterns were also evident: the older D. majalis showed greater accumulation of smRNAs near genes involved in transcriptional and translational regulation, while the younger D. traunsteineri displayed stronger non-additive patterns, suggesting ongoing resolution of post-polyploid meiotic and mitotic instability. Our results reveal both convergence and divergence in smRNA landscapes among independently formed allopolyploids. Our study highlights the central role of smRNAs in resolving genomic conflict, with possible implications for functional divergence and ecological innovation during polyploid evolution.

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.