New Phytologist最新文献

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.

In eukaryotes, XERODERMA PIGMENTOSUM GROUP D (XPD) is an integral subunit of the DNA repair/transcription complex TFIIH. In animals, XPD has been implicated in TFIIH-independent complexes regulating cell division, which, however, remains poorly understood in plants. Here, we identified XPD as a novel regulator of stomatal development in Arabidopsis. Its loss-of-function mutants exhibited increased stomatal precursor cells and formed stomatal clusters. Genetic analysis showed that XPD functions upstream of SPEECHLESS (SPCH) to control stomatal lineage entry, coordinates with MUTE to regulate meristemoid division and works together with FLP and FAMA to restrict GMC division. In a search of XPD interactors, we identified CDKA;1, which serves as both an essential cyclin-dependent kinase and a key SPCH activator. Consistently, xpd mutants exhibited enhanced stomatal lineage cell divisions and elevated SPCH protein levels. Furthermore, XPD acts upstream of CDKA;1, as expression of the dominant-negative CDKA;1.N146 allele significantly suppressed the excessive cell division and stomatal development defects in xpd plants. Our data highlight the precise regulation of stomatal development by XPD, expanding its critical TFIIH-independent roles in plant cell division and fate specification.

At high elevations, tree saplings and shrubs are usually protected by mid-winter snow cover, although climate change is expected to extend the snow-free (SF) period. Exposure to winter drought, freeze-thaw events and freezing temperatures will therefore increase, inducing damages to the hydraulic system and to living cells, resulting in reduced growth and increased mortality. A snow removal experiment was carried out at 1700 m. above sea level on saplings of five different species (Acer pseudoplatanus, Juniperus communis, Larix decidua, Picea abies and Sorbus aucuparia). Stem diameter was continuously monitored and compared with spring hydraulic conductivity (PLC_spring), living cell mortality (PLD_spring), nonstructural carbohydrates (NSCs), growth and survival rates. Under SF conditions, saplings had higher PLC_spring and higher PLD_spring, and thus experienced greater winter dehydration, resulting in lower growth compared with snow-covered saplings. Summer mortality was strongly correlated with PLC_spring and PLD_spring. These two key ecophysiological parameters predicted the risk of mortality in all species, whereas only PLD_spring reduced growth. By monitoring stem diameter during winter, we have defined indices to quantify resistance and recovery of woody plants under increased frost pressure. Recovery strategies such as resprouting or embolism repair were critical for survival, highlighting the potential vulnerability of saplings to climate change at high elevations.

Plant diversity is known to enhance soil resource availability and productivity through niche partitioning and facilitation; however, existing studies have predominantly examined these effects at the community level. The role of tree neighborhood diversity in alleviating nutrient limitations remains unclear. Here, using a tree diversity experiment in a subtropical forest with naturally low phosphorus (P) availability and depleted soil base cations, we evaluated how neighborhood diversity helps alleviate nutrient co-limitation. We found that greater neighborhood phylogenetic and trait dissimilarities enhanced growth rates and increased foliar P and magnesium (Mg) concentrations, as well as resorption efficiency in focal trees. Foliar Mg exhibited a more pronounced response than P and calcium (Ca), suggesting that diverse communities may prioritize alleviating Mg limitation over other nutrient limitations. Elevated foliar Mg concentration in focal trees were positively correlated with foliar transpiration, both driven by greater neighborhood phylogenetic dissimilarity. Our findings demonstrate that neighborhood diversity is essential in mitigating nutrient limitations on tree growth, highlighting the importance of phylogenetic and functional trait dissimilarities in mediating these positive effects.

The root nodule symbiosis between legumes and nitrogen-fixing bacteria (NFB) acts as an important nitrogen source in terrestrial ecosystems. NFB in soil are affected by top-down predation in the food web. However, how protist predation affects abundant and rare sub-communities of NFB remains virtually unknown, limiting the exploitation of soil food webs to promote plant productivity. Here, a 10-yr field experiment combined with a glasshouse experiment was conducted to explore the effects of protist predation on abundant and rare NFB under organic material amendments. Our results revealed that organic material amendments increased the diversity of rare NFB and phagotrophic protists, but decreased the relative abundance of abundant NFB Correlation analysis combined with the glasshouse experiment suggested that protist predation decreased the relative abundance of NFB abundant taxa, but increased the diversity of rare taxa, which further promoted the cytokinin content and decreased the ethylene content in peanut (Arachis hypogaea L.) roots. Subsequent changes in plant hormones regulated the expression of genes involved in rhizobial infection, nodule organogenesis, and bacteroid differentiation, thereby promoting nodulation and increasing peanut yield. Overall, our findings provide unique insights into the interactions between phagotrophic protists and NFB, highlighting their links with plant productivity via predation-stimulated symbiotic nitrogen fixation.

Crops increasingly face overlapping stresses such as heat, drought, salinity, and pathogens that conventional breeding or genome editing rarely overcome in combination. To address this, we propose CRISPR-enabled horizontal gene transfer (CRISPR-HGT) as a programmable framework that recreates the evolutionary process by which plants historically acquired adaptive microbial genes. Microbial genes, refined under extreme environments, provide a naturally preadapted resource for multi-trait resilience. By integrating tools such as Cas12a, CasΦ, RNA-targeting, and dCas-based epigenome editors with AI-guided microbial gene discovery, CRISPR-HGT enables modular and inducible stress regulation. This approach shifts genome editing from allelic modification to evolution-guided design. We outline a conceptual pipeline spanning microbial gene mining to adaptive field deployment, highlighting the ecological, biosafety, and regulatory dimensions, from the European Union's cautious oversight to the UK's product-based framework. CRISPR-HGT thus introduces an evolution-informed paradigm for engineering crops that anticipate stress and sustain yield under climate uncertainty.