New Phytologist最新文献

• Rice plants synthesize a unique group of diterpenoid phytoalexins (DPs) that exhibit broad-spectrum antimicrobial activities and are biosynthesized by enzymes encoded by three biosynthetic gene clusters. However, the regulatory mechanisms of their biosynthesis remain unclear.
• Here, the regulatory roles of the transcription factor OsWRKY10 and its interacting VQ motif-containing protein OsVQ8 in DPs biosynthesis and disease resistance were investigated via genetic and biochemical analyses. Their CRISPR/Cas9-mediated knockout and over-expressing (OE) lines, as well as crossed lines WRKY10_OE/vq8, were generated. OsVQ8 phosphorylation by mitogen-activated protein kinase (MAPK) cascades was examined.
• We found that OsWRKY10 co-expresses with and activates a specific set of genes involved in DPs biosynthesis, thereby enhancing DPs accumulation and disease resistance against both fungal blast and bacterial blight. We demonstrate that OsWRKY10 interacts with the VQ motif-containing protein OsVQ8, modulating DPs biosynthesis through OsVQ8 phosphorylation by the activated OsMKK4–OsMPK6 cascade upon perception of pathogen-associated molecular patterns.
• Our findings highlight how the interaction between OsVQ8 and OsWRKY10 serves as a molecular switch to regulate gene clusters and the entire pathway of DPs biosynthesis in rice and provides valuable insights for genetic engineering aimed at enhancing phytoalexin production and broad-spectrum disease resistance in staple food crops.

• The green seaweed Ulva compressa is a promising model for functional biology. In addition to historical research on growth and development, -omics data and molecular tools for stable transformation are available. However, more efficient tools are needed to study gene function.
• Here, we expand the molecular toolkit for Ulva.
• We screened the survival of Ulva and its mutualistic bacteria on 14 selective agents and established that Blasticidin deaminases (BSD or bsr) can be used as selectable markers to generate stable transgenic lines. We show that Cas9 and Cas12a RNPs are suitable for targeted mutagenesis and can generate genomic deletions of up to 20 kb using the marker gene ADENINE PHOSPHORIBOSYLTRANSFERASE (APT). We demonstrate that the targeted insertion of a selectable marker via homology-directed repair or co-editing with APT is possible for nonmarker genes. We evaluated 31 vector configurations and found that the bicistronic fusion of Cas9 to a resistance marker or the incorporation of introns in Cas9 led to the most mutants. We used this to generate mutants in three nonmarker genes using a co-editing strategy.
• This expanded molecular toolkit now enables us to reliably make gain- and loss-of-function mutants; additional optimizations will be necessary to allow for vector-based multiplex genome editing in Ulva.

• Some plants are known to actively close their stomata in the presence of foliar pathogens, inhibiting pathogen entry into leaves, leading to ‘stoma-based immunity’ as the first line of defense. However, the variation in stoma-based innate immunity across the diversity of vascular plants remains unclear.
• Here, we investigated the stomatal response and guard cell signaling pathway in various seed plant, fern, and lycophyte species when exposed to the bacterial pathogens or pathogen-associated molecular patterns (PAMPs).
• We observed active stomatal closure in 10 seed plants when exposed to bacteria or PAMPs, whereas none of the nine fern and one lycophyte species exhibited this response. The PAMP flg22-induced reactive oxygen species burst was observed in all species, but the downstream signaling events, including cytosolic Ca²⁺ accumulation, nitric oxide production, ion fluxes, vacuolar acidification, cytoplasmic pH elevation, vacuolar compartmentation, and disaggregation of the actin cytoskeleton in guard cells, were only observed in seed plants. No such changes were observed in the representatives of ferns and lycophytes.
• Our findings suggest a major difference in the regulation of stomatal immunity between seed plants and ferns and lycophytes under this study's conditions, unveiling physiological and biophysical mechanisms that may have underpinned the evolutionary adaptation of stomatal responses to pathogen attacks in seed plants.

• Nitrate is the main source of nitrogen in plants. Nitrate stimulation causes changes in plant secondary metabolites, including anthocyanins. However, the molecular mechanism underlying how nitrate regulates anthocyanin biosynthesis remains unclear. In this study, we identified a nitrate response factor MdLBD36 in apple. This factor positively regulated nitrate deficiency-induced anthocyanin biosynthesis by promoting the transcriptional activity of MdABI5, an important regulator of anthocyanins, and directly activated MdABI5 expression.
• The E3 ubiquitin ligase MdBRG3 promoted the ubiquitinated degradation of MdLBD36 to reduce anthocyanin biosynthesis under nitrate-sufficient conditions. Nitrate deficiency-activated MdMPK7 maintained the stimulating effect of MdLBD36 on anthocyanin biosynthesis by counteracting the MdBRG3-mediated degradation of MdLBD36.
• Nitrate coordinated gibberellin (GA) signaling to regulate anthocyanin biosynthesis. The GA signaling repressor MdRGL2a contributed to MdLBD36-promoted anthocyanin biosynthesis by enhancing the MdLBD36–MdABI5 interaction and increasing the MdLBD36 transcriptional activation of MdABI5.
• In summary, our results elucidate the molecular framework of the coordinated regulation of the nitrate signaling response and anthocyanin biosynthesis by ubiquitination and phosphorylation. This study revealed the cross talk between nitrate and GA signaling in the regulation of anthocyanin biosynthesis and provides references for an in-depth exploration of the nitrate signal transduction pathway and its interactions with hormones.

• The high sequence and structural similarities between BRASSINOSTEROID INSENSITIVE 1 (BRI1) brassinosteroid (BR) receptors of Arabidopsis (AtBRI1) and sorghum (SbBRI1) prompted us to study the functionally conserved roles of BRI1 in both organisms.
• Introducing sorghum SbBRI1 in Arabidopsis bri1 mutants restores defective growth and developmental phenotypes to wild-type levels.
• Sorghum mutants for SbBRI1 show defective BR sensitivity and impaired plant growth and development throughout the entire sorghum life cycle. Embryonic analysis of sorghum primary root techniques permits to trace back root growth and development to early stages in an unprecedented way, revealing the functionally conserved roles of the SbBRI1 receptor in BR perception during meristem development. RNA-seq analysis uncovers the downstream regulation of the SbBRI1 pathway in cell wall biogenesis during cell growth.
• Together, these results uncover that the sorghum SbBRI1 protein plays functionally conserved roles in plant growth and development, while encouraging the study of BR pathways in sorghum and its implications for improving resilience in cereal crops.

Human activities have caused atmospheric carbon dioxide (CO₂) concentrations to double since the onset of the industrial era, with levels continuing to rise at an unprecedented rate. This dramatic increase has far-reaching consequences for plant physiology, ecosystems, and global agriculture. While rising CO₂ may enhance plant growth through the well-known ‘CO₂ fertilisation’ effect (Ainsworth & Long, 2021), its influence on plant health is far more complex. Recent research has demonstrated that elevated CO₂ (eCO₂) can alter plant immune responses to pathogens, with highly variable outcomes. Reports indicate that eCO₂ can enhance, suppress or have no effect on plant resistance, depending on the specific host–pathogen interactions, environmental conditions, and pathogen lifestyles (Bazinet et al., 2022; Li & Ahammed, 2023; Sanchez-Lucas et al., 2023; Smith & Luna, 2023). This variability underscores the need to better understand the interplay between eCO₂ and plant immunity to predict the potential impacts of climate change on plant health. Plant diseases, caused by a wide range of pathogens, are among the most significant threats to global food security, biodiversity, and forest health. The spread and virulence of plant pathogens are already being shaped by climate change, making it critical to investigate how rising CO₂ interacts with plant defence mechanisms. The study by Bredow et al. recently published in New Phytologist (2025; doi: 10.1111/nph.20364) takes an important step towards addressing this knowledge gap. By evaluating how eCO₂ affects soybean in response to three distinct pathogen lifestyles (biotrophic, hemibiotrophic, and necrotrophic), the research provides a valuable framework for understanding the contrasting effects of eCO₂ reported in previous studies. Crucially, Bredow et al. explore the influence of eCO₂ under a concentration of 550 ppm, which reflects realistic projections for atmospheric CO₂ levels by 2050 (Hamdan et al., 2023). This approach enhances the relevance of their findings for understanding plant–pathogen dynamics in the near future, making their results directly applicable to ongoing discussions about the impacts of climate change on agriculture and ecosystems.

• Plant AP2/ERF (APETALA2/ethylene response factor) transcription factors are key regulators of environmental stress tolerance. We previously characterized that the wild soybean ERF71 transcription factor conferred bicarbonate stress tolerance; however, the underlying mechanism still remains elusive.
• Here, multiple approaches were used to identify the E3 ubiquitin ligase GmCHYR16 as an interactor of GmERF71. Ubiquitination and protein degradation of GmERF71 mediated by GmCHYR16 were then analyzed. Overexpression transgenic lines were generated to evaluate the function of GmCHYR16 and GmERF71 in bicarbonate stress response.
• GmCHYR16 interacts with GmERF71. GmERF71 proteins undergo ubiquitination and 26S proteasome-mediated degradation, and GmCHYR16 mediates the ubiquitination of GmERF71 for degradation. The GmCHYR16-mediated ubiquitination and proteasome-dependent degradation of GmERF71 are reduced under bicarbonate stress. GmCHYR16 expression in transgenic Arabidopsis, soybean hairy roots, and stable transgenic soybean reduces bicarbonate stress tolerance. GmERF71 degradation is decreased in the protein extracts of atchyr1/7 mutants, and atchyr1/7 mutants display higher bicarbonate tolerance. Overexpression of GmERF71 in transgenic soybean obviously increases bicarbonate tolerance, and GmCHYR16 reduces the bicarbonate tolerance of transgenic hairy root composite soybean plants by repressing GmERF71.
• Our results demonstrate that GmCHYR16 directly ubiquitinates GmERF71 for degradation and negatively regulates bicarbonate stress tolerance.