New Phytologist最新文献

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.

Although nitrogen (N) enrichment and precipitation changes are known to influence plant phenology and reproduction via altered soil nutrient and water availability, as well as above- and belowground biological processes, how these phenological changes affect reproduction remains unclear. Based on a field experiment with N addition and altered precipitation conducted in an alpine meadow on the eastern Tibetan Plateau since 2020, we explored their effects on plant reproductive phenology, reproductive output, and success from 2023 to 2024. N addition delayed the reproductive period, reduced the flowering asynchrony, and decreased both flower and fruit production in alpine plants. Notably, the interactive effects of N and precipitation addition significantly enhanced fruit set. Phenological shifts mediated plant reproductive responses to N addition and altered precipitation. Specifically, while N addition directly decreased flower and fruit production, it indirectly enhanced fruit set via phenological changes (including the peak flowering and the start of fruiting). These findings highlight the critical role of phenology in mediating alpine plant reproduction responses to N enrichment. Although delayed reproductive phenology enhances fruit set in alpine plants, its compensatory effect on N-induced reproductive losses remains limited under continuous nitrogen enrichment.

Postharvest pathogens can infect fresh produce both before and after harvest, by direct or wound-enhanced penetration, remaining quiescent until ripening. Biotrophic-like postharvest pathogens persist beneath host cells and can remain in a state of quiescence. They detect environmental cues and regulate quiescence through chromatin-level control and the secretion of effectors that interact with host pattern recognition receptors. By contrast, necrotrophic fungi persist between dead cells and depend more directly on nutrient availability to prime their growth and upon secretion for fungal virulence factors. During quiescence, the host also mounts specific responses, including activation of pattern recognition receptor genes, ethylene signaling (particularly in unripe fruit), and defense genes such as PR-10 and chitinases. Jasmonic acid and ethylene pathways synergistically enhance these defenses. As fruit ripens, the transition from quiescence to active necrotrophic growth is triggered, accelerating tissue decay. This activation is driven by several key factors, including weakened host defenses, decreased levels of antifungal compounds such as polyphenols, increased cell wall accessibility due to fruit softening and ripening-associated changes in signaling pathways, which alter environmental pH, carbon metabolism, and secondary metabolite production. These regulatory mechanisms collectively govern the timing and extent of fungal initiation of colonization during fruit senescence.

Argonaute2 (AGO2) largely participates in maintaining viral defenses. However, its function is not understood in species that are not commonly challenged by viruses in their native habitats. The ecological model species, Nicotiana attenuata, grows in arid/desert habitats. Natural virus infections are not commonly observed in this species even when the genes essential for viral defenses, like the RdRs, are silenced. The biological function of NaAGO2 has remained elusive. Silencing NaAGO2 with inverted-repeats (irAGO2) did not alter morphology, growth, or reproductive performance of unstressed plants compared to the wild-type (WT). irAGO2 was also able to defend against herbivores or pathogens and compete with con-species neighbors. However, irAGO2 had increased tolerance to water stress, exhibiting enhanced reproductive output during drought and recovery. Water-stressed irAGO2 accumulated significantly more abscisic acid (ABA) and proline, which are critical signaling and protective metabolites. Drought-responsive miRNA accumulation patterns were largely altered in irAGO2, potentially modulating ABA and proline gene expression during water stress and recovery. The function of three such Na-miRNAs (miR156, miR172, and miR398) was examined by transient overexpression in mitigating water stress and regulating ABA and proline pathways. We infer that AGO2 functions in fine-tuning ABA and proline homeostasis that optimizes N. attenuata's growth in complex stressful environments.

Seed dispersal modes play a crucial role in angiosperm migration, adaptation, and responses to climate change, yet their global spatiotemporal patterns and underlying drivers remain largely unexplored. Here, using a global dataset on seed dispersal modes (zoochory, anemochory, hydrochory, and autochory) of 35 131 angiosperm species, we provide a large-scale assessment of their evolutionary dynamics, diversification impact, and geographic variation. We found that the increase in zoochorous lineages began after c. 105 Ma, and the transition rate from abiotic-to-biotic dispersal strongly correlated with paleotemperature, being positive from 105 to 90 Ma and negative thereafter. However, contrary to previous hypotheses, we found no significant effect of seed dispersal mode on diversification rates across angiosperms. Spatially, the prevalence of zoochory declined, and that of autochory increased with latitude, both closely linked to contemporary temperature. Meanwhile, the frequency of zoochory and anemochory was positively associated with temperature anomalies since the Last Glacial Maximum, suggesting that dispersal modes facilitating long-distance dispersal are favored in climatically unstable regions. These findings highlight the key role of climate fluctuations in shaping the spatiotemporal patterns of angiosperm seed dispersal modes and suggest a more complex relationship between dispersal modes and angiosperm diversification than previously assumed.

The sapwood area supporting a given leaf area (Huber value, v_H) reflects the coupling between carbon uptake and water transport and loss at a whole-plant level. Geographic variation in v_H presumably reflects plant strategic adaptations, but the lack of a general explanation for such variation hinders its representation in vegetation models and assessment of its impact on the global carbon and water cycles. Here we develop a simple hydraulic trait model to predict optimal v_H by matching stem water supply and leaf water loss, and test its performance against two extensive plant hydraulic datasets. We show that our eco-evolutionary optimality-based model explains nearly 60% of global v_H variation in response to light, vapour pressure deficit, temperature and sapwood conductivity. Enhanced hydraulic efficiency with warmer temperatures reduces the sapwood area required to support a given leaf area, whereas high irradiance (supporting increased photosynthetic capacity) and drier air increase it. This study thus provides a route to modelling variation in functional traits through the coordination of carbon uptake and water transport processes.