Pollen hydration, germination, and tube growth are vital processes for the successful fertilization of flowering plants. These processes involve complex signaling pathways. Reactive oxygen species (ROS) generated in apoplast involves signaling for the cell wall expansion during tube growth, however molecular regulators are less known. We identified pollen-specific receptor-like kinase (OsPRK) family genes from rice (Oryza sativa), which have conserved leucine-rich repeat (LRR) and kinase domains. To understand the function of these genes, we produced single and triple mutations for OsPRK1, OsPRK2, and OsPRK3 using the clustered regularly interspaced palindromic repeats (CRISPR/Cas9) system. Among these mutants, triple knockout (KO) lines (osprk1/2/3) exhibited the male-sterile phenotype with normal vegetative growth and floret formation. Through cytological analysis, we confirmed that the reduced seed fertility was due to defects in pollen hydration and germination with low ROS accumulation. This defect of pollen germination was partially recovered by treatment with exogenous H₂O₂. We also confirmed that OsPRKs could interact with the LRR extension protein. Our results suggest that rice PRKs redundantly play a role in ROS signaling for pollen hydration and germination, and fertility can be controlled by exogenous application.

Plants have evolved a sophisticated chemical defense network to counteract pathogens, with phenolamides and salicylic acid (SA) playing pivotal roles in the immune response. However, the synergistic regulatory mechanisms of their biosynthesis remain to be explored. Here, we identified a biosynthetic gene cluster on chromosome 2 (BGC2) associated with the biosynthesis of phenolamide and SA, wherein the key component SlEPS1 exhibits dual catalytic functions for the synthesis of phenolamides and SA. Overexpression of the key component SlEPS1 of BGC2 in tomato enhanced resistance to the bacterial pathogen Pst DC3000, whereas knockout plants were more susceptible. Exogenous applications of SA and phenolamides revealed that these two compounds act synergistically to enhance plant resistance. Notably, during tomato domestication, a disease-resistant allele of SlEPS1, SlEPS1^HapB, was subject to negative selection, leading to a reduction in phenolamide and SA levels and compromised disease resistance in modern varieties. Moreover, the SlMYB78 directly regulates the BGC2 gene cluster to enhance phenolamide and SA biosynthesis, modulating resistance to Pst DC3000. Our study employed multi-omics approaches to describe the synergistic regulation of phenolamide and SA biosynthesis, offering new insights into the complexity of plant immune-related metabolism.

Gram-negative bacteria are known to release extracellular vesicles (EVs) into their surrounding environment. However, the biological functions of the proteins contained within these vesicles remain largely unknown. Here, we used tandem mass tag (TMT) proteomic analysis to characterize protein cargoes within EVs of the phytopathogen Pseudomonas syringae pv. tomato DC3000 (Pto DC3000). Our investigation revealed that one catalase, KatB, is enriched in bacterial EVs. This enzyme confers EVs with the capacity to detoxify both exogenous and plant-produced H₂O₂, thereby contributing to the pathogen's proliferation within the plants. Interestingly, reactive oxygen species (ROS) stress stimulates bacterial EV secretion and enhances the package of KatB into these vesicles. This regulatory process depends on a periplasmic ankyrin-like protein, AnkB. Both AnkB and KatB are encoded within a small operon, and their mutant strains exhibit impaired growth in plant hosts. Furthermore, the treatment of EVs pelleted from bacterial culture supernatants activates the immune responses of plants, and the absence of KatB in EVs further enhances this protective activity. Collectively, our findings indicate that bacteria secreted KatB via EVs to interact with and reduce the host's oxidative environment, thereby promoting their proliferation within plants.

Late blight, caused by the oomycete plant pathogen Phytophthora infestans, is a destructive disease that leads to significant yield loss in potatoes and tomatoes. The introgression of disease resistance (R) genes, which encode nucleotide-binding domain leucine-rich repeat-containing receptors (NLRs), into cultivated potatoes, is highly effective in controlling late blight. Here, we generated transgenic 2R and 3R potato lines by stacking R genes Rpi-blb2/Rpi-vnt1.1 and Rpi-vnt1.1/RB/R8, respectively, in the susceptible cv. Desiree background. The resulting 2R and 3R transgenic potato plants showed resistance to highly virulent P. infestans field isolates. We hypothesized that stacking R genes either resulted in up-regulation of a broader range of immune-related genes, or, more importantly, increase in the fold change of gene expression. To test our hypotheses, we performed transcriptome analysis and identified a subset of core immune-related genes that are induced in response to P. infestans in transgenic lines carrying single R genes versus lines carrying stacks of multiple R genes. In our analysis, stacking R genes resulted not only in the induction of a broader range of defense-associated genes but also a global increase in gene expression fold change, caused by the pathogen. We further demonstrated that the calcium-dependent protein kinase 16 (StCDPK16) gene significantly contributed to resistance to a virulent P. infestans strain, in the R gene background, in a kinase activity-dependent manner. Thus, our data suggest that stacking the R genes enhances late blight resistance through modulating the expression of a broader range of defense-related genes and highlights CDPK16 as a novel player in potato R gene-mediated resistance.

Silicon (Si) plays a crucial role in plant growth, development, and stress tolerance. However, in some consumable plant products, such as fruits, Si deposition leads to the formation of a white powdery layer known as bloom, which diminishes glossiness and consumer appeal. Despite its significance, the genetic basis of bloom formation remains largely unexplored. Here, we identified a unique cucumber backbone parent line exhibiting bloomless fruit, which was designated bloomless cucumber 1 (bec1). Map-based cloning of the bec1 locus revealed that BEC1, harboring a natural C-to-T variation at the 754th base of its coding region, is a strong candidate gene for the bloomless trait. Functional validation through gene-editing mutants and BEC1::BEC1-GFP transgenic lines confirmed that BEC1, encoding a Si efflux transporter, is responsible for bloom formation. Mutation of BEC1 impaired Si uptake, thereby preventing the deposition of Si on the surface of glandular trichomes and resulting in bloomless fruits. Additionally, Si deficiency in BEC1 mutants compromised resistance to Corynespora cassiicola and chilling stress. Interestingly, grafting bec1 scions onto bloom rootstocks restored the Si accumulation and stress resistance, while maintaining bloomless phenotype. Overall, our findings elucidate the role of BEC1 in bloom formation and provide a valuable genetic target for breeding bloomless cucumber with enhanced stress resilience.

Sweetpotato (Ipomoea batatas) starch is in high demand globally as a food and industrial product. However, the regulatory mechanisms governing starch biosynthesis and starch properties in this important crop remain largely unknown. Here we identified a natural allelic variant in the promoter of IbNAC22, encoding a NAC (NAM, ATAF1/2, and CUC2) transcription factor, which is closely linked to starch content in sweetpotato. In high-starch sweetpotato varieties, the T/C haplotype and a 13-bp deletion in the IbNAC22 promoter resulted in higher transcriptional activity. The high-starch IbNAC22 haplotype is more prevalent in regions of China where the sweetpotato starch industry is well developed, indicating that this advantageous allele type has been utilized in breeding starchy sweetpotato varieties in China. IbNAC22 is highly expressed in storage roots and starch-rich sweetpotato accessions. Overexpression of IbNAC22 significantly improved starch and amylose contents, as well as granule size and gelatinization temperature, and decreased starch crystallinity, whereas IbNAC22 knockdown had the opposite effects. IbNAC22 directly activates the expression of IbGBSSI, a key gene for amylose biosynthesis, but suppresses the expression of IbSBEI, a key gene for amylopectin biosynthesis. IbNAC22 directly interacts with IbNF-YA10. Overexpressing of IbNF-YA10 significantly improved starch and amylose contents, and starch gelatinization temperature, but decreased granule size, crystallinity, and amylopectin chain length distribution. IbNF-YA10 directly activates IbAGPL and IbGBSSI, which are key genes involved in starch and amylose biosynthesis. IbNAC22–IbNF-YA10 heterodimers further enhance the IbNF-YA10-induced activation of IbAGPL and IbGBSSI. These findings increase our understanding of starch biosynthesis and starch properties and provide strategies and candidate genes for the improvement of starchy root and tuber crops.

Budding speciation is a process wherein a new species arises from a small, isolated population within or at the margin of an ancestral species. Well-documented cases of budding speciation are rare, and the roles of various evolutionary factors in this process remain controversial. Based on whole-genome resequencing data from 272 individuals across 27 populations, we reconstructed the evolutionary history of Rhodiola sect. Trifida and explored the relative contributions of natural selection, genetic drift, and chromosomal rearrangements as drivers of lineage divergence. We found that all samples of R. chrysanthemifolia (including R. alterna and R. sinuata) were clustered into three clades. Rhodiola liciae was sister to all other samples in the section, likely due to post-divergence gene flow and the minimal population structure of the progenitor species, while it shared the same ancestry with R. ch-I in population structure analyses. The two populations of R. sinuata were not monophyletic, instead clustering with geographically proximate populations of R. ch-III. Demographic analyses revealed that R. liciae underwent a contraction in population size following its divergence from R. ch-I approximately 0.34 million years ago (Mya), and has remained stable since around 0.1 Mya. Genomic islands and genotype-environment association analyses suggested that genetic drift and the assorting of ancestral polymorphism may have played a more significant role in the speciation of R. liciae than nature selection or chromosomal rearrangements. We propose that R. liciae diverged from R. chrysanthemifolia through budding speciation, although post-divergence gene flow has obscured its phylogenetic signal. Additionally, we identified two potential parallel budding speciation events in R. sinuata at an earlier stage than R. liciae. Our study highlights budding speciation as a prevalent yet poorly characterized mode of plant speciation, with assorting of ancestral polymorphism as a key stochastic mechanism in the process.

Transgenic and gene-editing technologies are essential for gene functional analysis and crop improvement. However, the pleiotropic effects and unknown mechanisms of morphogenic genes have hindered their broader application. In this study, we employed the one-step de novo shoot organogenesis (DNSO) method, and demonstrated that overexpression of the morphogenic gene Arabidopsis thanalia GROWTH-REGULATING FACTOR 5 (AtGRF5) significantly enhanced genetic transformation efficiency in cucurbit crops by promoting callus proliferation and increasing dense cells during regeneration. High-resolution time-series transcriptomics and single-cell RNA sequencing revealed that AtGRF5 overexpression induced auxin-related genes and expanded stem cell populations during cucumber DNSO. Using DNA-affinity purification sequencing (DAP-seq) in combination with spatiotemporal differential gene expression analysis, we identified CsIAA19 as a key downstream target of AtGRF5, with its modulation playing a pivotal role in regeneration. Rescuing CsIAA19 in AtGRF5-overexpressing explant reversed the enhanced callus proliferation and regeneration. To address growth defects caused by AtGRF5 overexpression, we developed an abscisic acid-inducible AtGRF5 expression system, significantly improving transformation and gene-editing efficiency across diverse genotypes while minimizing pleiotropic effects. In summary, this research provides mechanistic insights into AtGRF5-mediated transformation and offers a practical solution to overcome challenges in cucurbit crop genetic modification.

Radish (Raphanus sativus L.) is a globally important root vegetable crop known for its diverse varieties and unique taproot characteristics. The LBD (LATERAL ORGAN BOUNDARIES DOMAIN) gene family, specific to plants, plays a pivotal role in the development of lateral plant organs. Nonetheless, the precise biological functions and molecular regulatory mechanisms of LBD genes in radish taproot development remain largely unexplored. In this study, the RsLBD3 gene was identified as a potential candidate affecting taproot size in radish through a genome-wide association study. Further investigation revealed two insertions in the C-terminal region of RsLBD3, with insertion³⁶³ notably enhancing the transcriptional activation capability of RsLBD3. It was observed that radish taproots with RsLBD3^Ins-363 haplotype displayed significantly greater length and weight compared to those with RsLBD3^Del-363 haplotype. RNA in situ hybridization and reverse transcription quantitative polymerase chain reaction analysis revealed that the RsLBD3 gene exhibits high expression level in the vascular cambium and is induced by cytokinin treatment. Silencing the RsLBD3 gene resulted in the inhibition of vascular cambium activity in the taproot, thereby impeding thickening. Exogenous cytokinin treatment could partially rescue the small-taproot phenotypes caused by RsLBD3 silencing. Moreover, RsARF5 (AUXIN RESPONSE FACTOR 5), RsRR7b (RESPONSE REGULATOR 7), and RsCYCD3-1 (CYCLIN D3;1) were identified as target genes of RsLBD3. Notably, RsARF5 was found to directly regulate the expression of RsWOX4 (WUSCHEL-RELATED HOMEOBOX 4). Additionally, biochemical analysis demonstrated that RsTCP14 interacts with RsLBD3, contributing to the binding of RsLBD3 to its target genes. Collectively, these findings contribute to a better understanding of the regulatory mechanisms underlying taproot morphogenesis, and provide novel allelic variations for the genetic enhancement of taproot shape traits in radish.

Leaf curvature significantly contributes to important economic traits in vegetable crops. The upward-curling leaf phenotype has been consistently observed upon overexpression of a miR156/157-resistant version of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 10 (SPL10) transcription factor (rSPL10). However, the role of SPL10 in regulating leaf curvature has not been well characterized. In this study, using DNA affinity purification sequencing followed by transient transactivation assays, we found that SPL10 can bind to the promoter and gene body of REVOLUTA (REV), augmenting its expression. The rSPL10 rev-6 double mutant plant displayed a downward-curling leaf phenotype similar to the rev-6 plant, supporting the notion that REV functions downstream of SPL10. Importantly, the SPL10 protein physically interacts with the REV protein, which attenuates the expression of REV promoted by SPL10, leading to the downregulation of REV-regulated genes involved in leaf curvature, such as HB2 and HB4. These findings suggest that the SPL10–REV module acts as a molecular rheostat to prevent excessive amplification of REV transcripts in Arabidopsis. Furthermore, overexpression of the BrpREV1 gene in Chinese cabbage caused the transformation of rosette leaves from flat to upward-curving and accelerated heading. Taken together, our findings reveal the role of SPL10–REV module in orchestrating leaf curvature, which could potentially be utilized for molecular breeding of economical traits in vegetable crops.

The calcineurin B-like protein (CBL)-CBL-interacting protein kinase (CIPK) Ca²⁺ sensors play crucial roles in the plant's response to drought stress. However, there have been few reports on the synergistic regulation of drought stress by CBL-CIPK and abscisic acid (ABA) core signaling components. In this study, we discovered that ZmCIPK33 positively regulates drought resistance in maize. ZmCIPK33 physically interacts with and is enhanced by phosphorylation from ZmSnRK2.10. Drought stress can activate ZmCIPK33, which is partially dependent on ZmSnRK2.10. ZmCIPK33 in combination with ZmSnRK2.10 can activate the slow anion channel ZmSLAC1 in Xenopus laevis oocytes independently of CBLs, whereas ZmCIPK33 or ZmSnRK2.10 alone is unable to do so. Furthermore, ZmCIPK33 phosphorylates ZmPP2C11 at Ser60, which leads to a reduction in the interaction between ZmPP2C11 and ZmEAR1 (the ortholog of Arabidopsis Enhancer of ABA co-Receptor 1) and weakens the phosphatase activity of ZmPP2C11, consequently, enhancing the activity of ZmSnRK2.10 in an in vitro assay and in the in-gel assay of the zmcipk33 mutant. Our findings provide novel insights into the molecular mechanisms underlying the reciprocal enhancement of Ca²⁺ and ABA signaling under drought stress in maize.

Pitaya is an important perennial herbaceous fruit tree. The color of fruit determines pitaya nutritive (and attractive) value, which is considered as an important objective in breeding improvement. In this study, we reported the first telomere-to-telomere (T2T) gap-free genome of “Shuangse No. 1” pitaya (Hylocereus polyrhizus; red peel). Two high-quality genomes for “Dahong” (H. polyrhizus; red peel) and “Honghuaqinglong” (H. stenopterus; stay-green) were further assembled, aiming to explore the genetic diversity of pitaya genomes. In further analysis, we noticed a high proportion of viral contamination in pitaya tissues, which hindered the efficient utilization of transcriptomic data. To address this issue, we analyzed 111 pitaya transcriptome data from different geographic regions to characterize and separate viral components. Then we developed an efficient, novel, and universal transcript purification system for pitaya transcriptomes by applying it to 27 samples from different tissues and species, thereby enhancing the utility for transcriptomic and broader biological research. Combining the purified transcriptomic data with comparative genomic analyses, we identified HuERF72, a transcription factor (TF) that potentially regulates chlorophyll degradation in pitaya. Interaction assays and plant transformation elucidated that HuERF72 acts as a repressive TF by directly binding to the promoter of HuSGR1, a key structural gene in the chlorophyll degradation pathway. This study provides high-quality genomic resources and novel methodologies for molecular investigations in pitaya. Additionally, the proposed regulatory network advances our understanding of the transcriptional regulatory mechanisms underlying chlorophyll degradation, offering valuable insights into the genetic improvement of pitaya.

Light is a fundamental environmental cue that dynamically orchestrates plant growth and development through spatiotemporally regulated molecular networks. Among these, phosphorylation, a key post-translational modification, plays a crucial role in controlling the function, stability, subcellular localization, and protein–protein interactions of light signaling components. This review systematically examines phosphorylation-dependent regulatory events within the Arabidopsis light signaling cascade, focusing on its regulatory mechanisms, downstream functional consequences, and crosstalk with other signaling pathways. We underscore the pivotal role of phosphorylation in light signaling transduction, elucidating how the phosphorylation-decoding framework transduces light information into growth and developmental plasticity to modulate plant–environment interactions.

Bamboo is a fast-growing and ecologically significant plant with immense economic value due to its applications in construction, textiles, and bioenergy. However, research on bamboo has been hindered by its long vegetative period, unpredictable flowering cycles, and challenges in genetic transformation. Recent developments in advanced sequencing and genetic engineering technologies have provided new insights into bamboo's evolutionary history, developmental biology, and stress resilience, paving the way for improved conservation and sustainable utilization. This review synthesizes the latest findings on bamboo's genomics, biotechnology, and the molecular mechanisms governing its growth, development, and stress response. Key genes and regulatory pathways controlling its rapid growth, internode elongation, rhizome development, culm lignification, flowering, and abiotic stress responses have been identified through multi-omics and functional studies. Complex interactions among transcription factors, epigenetic regulators, and functionally important genes shape bamboo's unique growth characteristics. Moreover, progress in genetic engineering techniques, including clustered regularly interspaced short palindromic repeats-based genome editing, has opened new avenues for targeted genetic improvements. However, technical challenges, particularly the complexity of polyploid bamboo genomes and inefficient regeneration systems, remain significant barriers to functional studies and large-scale breeding efforts. By integrating recent genomic discoveries with advancements in biotechnology, this review proposes potential strategies to overcome existing technological limitations and to accelerate the development of improved bamboo varieties. Continued efforts in multi-omics research, gene-editing applications, and sustainable cultivation practices will be essential for harnessing bamboo as a resilient and renewable resource for the future. The review presented here not only deepens our understanding of bamboo's genetic architecture but also provides a foundation for future research aimed at optimizing its ecological and industrial potential.

Serotonin (5-hydroxytryptamine (5-HT)) is a pineal hormone and a secondary metabolite related to various hormonal and physiological functions at the organ, tissue, and cellular levels. It is considered increasingly important in regulating animal behavior, but the function of serotonin in plants is far less known. According to recent research, serotonin is vital for plant growth, development, and stress responses, achieved through transcriptional and phytohormonal interplay. Specifically, this review addresses critical gaps in the understanding of serotonin's function in plants by examining its biosynthesis, metabolism, and its multifaceted role in mitigating both abiotic stresses (salinity, drought, heat, cold, and heavy metals) as well as biotic challenges (pathogens, pests, and herbivores). As a pivotal player, it engages in a variety of significant cellular and molecular interactions, including those with reactive oxygen and nitrogen species (RONS), and various phytohormones such as auxin, abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and cytokinin (CK). Advances in serotonin-related research are anticipated to offer a valuable basis for uncovering the regulatory pathways by which serotonin impacts the resilience of crops against abiotic stress.

Deep learning-based genomic prediction (DL-based GP) has shown promising performance compared to traditional GP methods in plant breeding, particularly in handling large, complex multi-omics data sets. However, the effective development and widespread adoption of DL-based GP still face substantial challenges, including the need for large, high-quality data sets, inconsistencies in performance benchmarking, and the integration of environmental factors. Here, we summarize the key obstacles impeding the development of DL-based GP models and propose future developing directions, such as modular approaches, data augmentation, and advanced attention mechanisms.

Successful reproduction depends on the stable germination and growth of the pollen tubes (PT). However, the molecular mechanisms involved in rice PT growth and development remain largely unknown. In a previous study, microarray transcriptome analysis identified 627 genes preferentially expressed in the tricellular and germinating pollen of rice (i.e., Oryza sativa ssp. japonica). To elucidate key genes involved in the gene transfer process facilitated by male gametophytes, we systematically screened T-DNA lines containing disrupted sequences that corresponded to these 627 genes and analyzed the genotypes of heterozygote progeny from 107 T-DNA-indexed lines covering 105 genes. We found that 42 lines exhibited a distorted segregation ratio among the wild-type (WT), heterozygote (HT), and homozygote (HM) genotypes, which deviated from the expected Mendelian ratio of 1:2:1 (WT:HT:HM). Further characterization using CRISPR/Cas9 mutants revealed that knockout mutants of certain genes that exhibited segregation distortion in the T-DNA insertion region were completely sterile. Moreover, even when T-DNA insertion lines followed Mendelian segregation patterns, sterility could be induced by simultaneously mutating functionally redundant genes, thereby overcoming genetic compensation. Interestingly, although some T-DNA insertion lines exhibited segregation ratios approximating 1:1:0, the corresponding CRISPR/Cas9 mutants produced homozygous seeds and showed partial sterility. Partial sterility suggests that despite mutant pollen grains being less competitive than WT pollen, they retain their fertilization potential under relaxed competition from WT pollen. Beyond mutant-based analysis, transcriptomic profiling of sterile mutant lines provided additional insight into the regulatory relationship between key germination regulators and the 105 target genes studied here. Overall, this study demonstrates the effectiveness of a multi-pronged strategy to accelerate the identification of defective phenotypes using mutant studies and provides valuable genetic resources for inducing novel male sterility in rice.

Seedlessness is a most valuable trait in fruit crops for fresh consumption and processing. The mutations in essential meiosis genes are known to confer sterility and seed abortion in plants. However, defects in meiosis have rarely been reported in fruit crops. Here, we found meiosis defects caused sterility in a seedless citrus bud sport cultivar, with massive unpaired univalents during diakinesis, indicating a disruption in crossover formation. A non-functional CrMER3A^{-103 bp} allele with a 103-bp deletion in the gene body, together with the other non-functional CrMER3a allele with a T deletion in exon, were identified in the seedless cultivar. The CrMER3 protein was undetectable at meiotic prophase I in the seedless cultivar, and knock out of CrMER3 resulted in sterility in precocious Mini-citrus. Therefore, the natural variation in CrMER3 is responsible for sterility and seedlessness in this bud sport cultivar. The CrMER3a allele originated from the primitive wild mandarin and was passed to cultivated mandarins. A Kompetitive Allele-Specific PCR (KASP) marker was developed to identify citrus germplasm with CrMER3a allele and to screen potential sterile and seedless hybrids in citrus cross breeding. Uncovering the natural mutations responsible for meiosis defects in citrus enhances our understanding of mechanisms controlling seedlessness in fruit crops and facilitates breeding of seedless varieties.

Rice production is severely impacted by pathogens such as Magnaporthe oryzae and the rice stripe virus (RSV). Ineffectiveness in controlling viruses and the excessive use of fungicides have proven traditional chemical pesticides increasingly inadequate. RNA interference (RNAi) represents a cutting-edge approach for combating crop diseases, especially in rice. This study addresses the critical gap in scalable, effective RNAi-based rice disease management by exploring the potential of spray-applied small RNA (sRNA) and double-stranded RNA (dsRNA) molecules. We utilized dsRNAs produced by in vitro transcription and bacterial expression systems and employed layered double hydroxides (LDH) to enhance RNA stability, absorption, and efficacy. Our research demonstrated that modified sRNAs could effectively penetrate M. oryzae cell membranes and inhibit conidial germination and appressorium formation, while LDH-conjugated dsRNAs provided prolonged and enhanced protection against both rice blast and rice stripe diseases. Most importantly, dsRNA treatments resulted in improved agronomic traits or increased crop yields by protecting against blast and stripe diseases. This study also validated the compatibility of these RNA molecules with industrial production methods, highlighting their potential as a scalable and eco-friendly option for managing crop diseases at the gene level. This work not only offers a new direction for rice disease control but also provides a foundation for the broader application of RNAi technology in agricultural pest management.

Mitogen-activated protein kinase (MAPK) cascades play a fundamental role in plant immunity by transducing external signals inside plant cells. Here, we defined a wheat MAPK cascade, composed of the mitogen-activated protein kinase kinase (MAPKK) TaMKK2 and its downstream MAPK TaMAPK6, which phosphorylates the core immune regulator TaSGT1 (suppressor of G2 allele of Skp1), resulting in enhanced nuclear entry of TaSGT1, thereby conferring resistance against the devastating wheat pathogen Puccinia striiformis f. sp. tritici (Pst). Hence, we identified a TaMKK2-TaMAPK6-TaSGT1 signaling cascade that contributes to wheat stripe rust resistance. During infection, Pst secrets a haustorium-associated secreted protein 215 (HASP215), that targets TaMKK2 and interferes with the interaction of TaMKK2 with TaMAPK6 to suppress TaMAPK6 phosphorylation and activation, thereby leading to reduced capacity of TaMAPK6 to phosphorylate TaSGT1. Consequently, inhibition of TaMAPK6-mediated TaSGT1 phosphorylation resulted in decreased nuclear translocation of TaSGT1 and suppressed plant immunity. Our work elucidates the positive function of TaMKK2-TaMAPK6 cascade in wheat immunity by regulating the immune component TaSGT1, and its regulation by the rust effector HASP215, providing new insights into the MAPK cascade on crop immunity and the pathogenicity mechanism of obligate biotrophic fungus.

Rice bacterial blight, caused by the pathogen Xanthomonas oryzae pv. oryzae (Xoo), poses a significant threat to rice crops. Arginine methylation, a post-translational modification of proteins, plays a pivotal role in transcriptional regulation, RNA processing, and the biosynthesis of plant hormones. Previous research has established that protein arginine methyltransferases (PRMTs) significantly influence protein function through arginine methylation. Nonetheless, the specific role of PRMT5 in regulating salicylic acid (SA) biosynthesis and plant immunity has been relatively unexplored. In this study, we elucidate the role of a rice protein arginine methyltransferase, OsPRMT5, in enhancing rice resistance to Xoo infection by interacting with the SA biosynthesis enzyme phenylalanine ammonia lyase 1 in rice (OsPAL1). Our results indicate that OsPRMT5 methylates OsPAL1 at the arginine residue 75, which affects the interaction between OsPRMT5 and OsPAL1 and subsequently boosts phenylalanine ammonia lyase (PAL) enzyme activity, leading to heightened SA accumulation. Conversely, compared to OsPAL1 overexpression plants in wild-type TP309 background, OsPAL1 overexpression plants in osprmt5 knockout (KO) mutants background exhibited diminished PAL activity. Furthermore, osprmt5 ospal1 double mutants demonstrated reduced resistance to bacterial blight compared to the OsPAL1-KO group. Additionally, we discovered that the Xoo effector protein PXO_01039 undermines the interaction between OsPRMT5 and OsPAL1, thereby facilitating Xoo infection. PXO_01039 binds to OsPRMT5, preventing the formation of the OsPRMT5-OsPAL1 complex, which results in decreased PAL activity and lower SA accumulation. In conclusion, our findings unveil how OsPRMT5 modulates the methylation and enzymatic activity of OsPAL1, a crucial enzyme in SA biosynthesis, to bolster plant antibacterial defenses.

Synthetic microbial communities (SynComs) are a promising tool for making full use of the beneficial functions imparted by whole bacterial consortia. However, the complexity of reconstructed SynComs often limits their application in sustainable agriculture. Furthermore, inter-strain interactions are often neglected during SynCom construction. Here, we propose a strategy for constructing a simplified and functional SynCom (sfSynCom) by using elite helper strains that significantly improve the beneficial functions of the core symbiotic strain, here Bradyrhizobium elkanii BXYD3, to sustain the growth of soybean (Glycine max). We first identified helper strains that significantly promote nodulation and nitrogen fixation in soybean mediated by BXYD3. Two of these helper strains assigned to the Pantoea taxon produce acyl homoserine lactones, which significantly enhanced the colonization and infection of soybean by BXYD3. Finally, we constructed a sfSynCom from these core and helper strains. This sfSynCom based on the core-helper strategy was more effective at promoting nodulation than inoculation with BXYD3 alone and achieved effects comparable to those of a complex elite SynCom previously constructed on the basis of potential beneficial functions between microbes and plants alone. Our results suggest that considering interactions between strains as well as those between strains and the host plant might allow construction of sfSynComs.

Maintenance of endoplasmic reticulum (ER) homeostasis is central for plants to survive in changing cellular and environmental conditions. Although the role of ER in plant immunity is evident, how ER homeostasis is associated with activation of the immune response remains unclear. Here, we report that StDMP2, an ER-localized member of the DOMAIN OF UNKNOWN FUNCTION 679 membrane protein (DMP) family, positively regulates resistance to Phytophthora in potato (Solanum tuberosum). Heterologous expression of StDMP2 in tobacco (Nicotiana benthamiana) also enhances resistance to Phytophthora. Furthermore, StDMP2 is involved in both chemical- and pathogen-induced ER stress responses. Notably, StDMP2 plays a crucial role in several pathogen-associated molecular pattern-triggered immunity responses, and specifically contributes to the hypersensitive response triggered by the bacterial type-III secreted effector AvrRpt2, but not the Phytophthora infestans-secreted effector Avr3a. Further investigation revealed that StDMP2 affects the ER quality control-mediated accumulation of specific pattern recognition receptors and NON-RACE SPECIFIC DISEASE RESISTANCE 1. Collectively, these findings elucidate a mechanism by which StDMP2 promotes plant immunity through modulating ER homeostasis.

In plants, the photoperiod sensitivity directly influences flowering time, which in turn affects latitudinal adaptation and yield. However, research into the mechanisms underlying photoperiod sensitivity, particularly those mediated by epigenetic regulation, is still in its nascent stages. In this study, we analyzed the regulation of photoperiod sensitivity in Arabidopsis thaliana. We demonstrate that the evening complex LUX ARRYTHMO (LUX) and the chromatin remodeling factor SWITCH/SUCROSE NONFERMENTING 3C (SWI3C) regulate GI locus chromatin compaction and H3K4me3 modification levels at the GIGANTEA locus under different photoperiod conditions. This mechanism is one of the key factors that allow plants to distinguish between long-day and short-day photoperiods. Our study provides insight into how the LUX-SWI3C module regulates photoperiod sensitivity at the epigenetic level.

Sex chromosomes have evolved independently in numerous lineages across the Tree of Life, in both diploid-dominant species, including many animals and plants, and the less studied haploid-dominant plants and algae. Strict genetic sex determination ensures that individuals reproduce by outcrossing. However, species with separate sexes (termed dioecy in diploid plants, and dioicy in haploid plants) may sometimes evolve different sex systems, and become monoicous, with the ability to self-fertilize. Here, we studied dioicy-monoicy transitions in the ancient liverwort haploid-dominant plant lineage, using three telomere-to-telomere gapless chromosome-scale reference genome assemblies from the Ricciaceae group of Marchantiales. Ancestral liverworts are believed to have been dioicous, with U and V chromosomes (chromosome 9) determining femaleness and maleness, respectively. We confirm the finding that monoicy in Ricciocarpos natans evolved from a dioicous ancestor, and most ancestrally U chromosomal genes have been retained on autosomes in this species. We also describe evidence suggesting the possible re-evolution of dioicy in the genus Riccia, with probable de novo establishment of a sex chromosome from an autosome (chromosome 5), and further translocations of genes from the new sex chromosome to autosomes. Our results also indicated that micro-chromosomes are consistent genomic features, and may have evolved independently from sex chromosomes in Ricciocarpos and Riccia lineages.