New Phytologist最新文献

Nonphotochemical quenching (NPQ) mechanisms fine-tune light utilisation in the photosynthetic antenna, for example, in response to excess light, to prevent photodamage. NPQ comprises distinct mechanisms, all contributing to photoprotection but acting on different time scales. Preferences for individual mechanisms and NPQ composition are proposed to reflect the organism's lifestyle, especially regarding sessile vs motile styles, with the latter enabling photophobic responses. We analysed photoprotection in the nonmotile, unicellular chlorophycean microalga Botryosphaerella sudetica, belonging to a genus known to form high-light-exposed floating aquatic biofilms. Growth, Chl fluorescence, its nuclear genome, and the expression of photoprotective genes were analysed in comparison with the motile chlorophycean microalga Chlamydomonas reinhardtii. These analyses revealed that B. sudetica is, in contrast to C. reinhardtii, equipped with a constitutive energy-dependent quenching (qE) mechanism based on the constitutive accumulation of protein PSBS, the thylakoid lumen pH-sensor, found throughout the green plant lineage. While qE was the predominant NPQ mechanism in B. sudetica and required zeaxanthin formation, state transitions (qT), which largely contributed to NPQ in C. reinhardtii, played a minor role. These data demonstrate that a core set of NPQ mechanisms conserved in the Viridiplantae is shuffled to meet better the adaptive requirements imposed by the habitat.

Rapid environmental change reshapes both abiotic stress and biotic interactions, yet it remains unclear how these combined forces structure plants' genomic adaptation. In particular, the joint influence of temperature and pollinator identity, two ecological axes undergoing simultaneous global shifts, has rarely been quantified at genomic resolution. We resequenced Brassica rapa L. plants after a six-generation evolution experiment, combining two temperature regimes (ambient vs hot) with three pollination treatments (bumblebee, butterfly, and mixed bumblebee-butterfly), and glasshouse control, to assess how these factors shape genomic responses. Using multiple complementary statistics (allele-frequency trajectories, F_ST outliers, Cochran-Mantel-Haenszel tests, and local score analyses), we found that adaptive genomic responses differed sharply among pollinators and temperatures: warming strengthened selection in community-level pollination, yielding the clearest signals in the hot-generalised treatment; bumblebee pollination showed strong but drift-obscured genomic change; and butterfly treatments exhibited minimal genomic response. Our findings demonstrate that pollinator identity and temperature interact nonadditively to produce distinct, highly context-dependent adaptive trajectories. This work highlights the importance of accounting for demographic variation and ecological complexity when predicting evolutionary responses to climate-driven shifts in species interactions.

Generation of competent offspring is vital for the prosperity of flowering plants. The pistil not only functions as a conduit for pollen tubes to grow to the ovary but also provides a selective venue for facilitating the growth of compatible pollen tubes and discouraging invaders and incompatible pollen. This review integrates recent advances in pollen-pistil interactions on dry stigmas of the Brassicaceae in the domains of self-incompatibility (SI) and cross-compatibility. We first outline the initial recognition mechanisms that distinguish self from nonself pollen and then highlight how key stigma responses are differentially regulated during compatible and incompatible responses, including calcium signaling, exocytosis, cytoskeleton dynamics, reactive oxygen species, aquaporin activity, and cell wall permeability. By linking these discrete cellular events to their physiological outcomes, we provide a unified framework for understanding how Brassicaceae stigmas precisely control fertilization. A deeper understanding of these mechanisms also informs new strategies for improving crop breeding in economically important Brassicaceae species, which widely use SI to produce F1 hybrid seeds.

Mycorrhizal symbioses represent one of the most widespread and ecologically significant plant-microbe interactions, shaping plant nutrition, stress resilience, and ecosystem functioning. Beyond their role in nutrient exchange and systemic defense, growing evidence suggests that these symbioses also influence plant plasticity within and across generations through epigenetic regulation. These mechanisms operate throughout the mutualistic interaction, from fungal recognition and root colonization to symbiosis functioning, by regulating gene networks that control signaling, defense suppression, and nutrient exchange. By integrating environmental cues into potentially heritable gene regulatory states, epigenetic regulation fine-tunes within-generation responses and may also contribute to effects across generations, thereby influencing adaptation and resilience. The extent of mycorrhiza-induced epigenetic inheritance likely depends on the host's reproductive strategy and lifespan. Clonal propagation and shorter-lived hosts tend to preserve epigenetic marks, whereas sexual reproduction and longer-lived species show partial resetting. This contrast shapes offspring performance, ecological interactions, and evolutionary trajectories. Here, we synthesize current knowledge on the epigenetic regulation of mycorrhizal symbioses, draw parallels with other plant-microorganism interactions (including plant-pathogens and plant-endophytes), highlight its role in within-generation plasticity and propose a potential role across generations. We outline future research directions to disentangle the stability, ecological relevance, and evolutionary significance of mycorrhiza-mediated epigenetic inheritance.

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.