Soil salinization and alkalization have become an increasingly severe global issues, significantly limiting both the yield and quality of apples (Malus × domestica). M9-T337 is a widely used apple dwarfing rootstock; however, it is sensitive to saline-alkali stress. Therefore, developing saline-alkali tolerant apple rootstocks is essential. In this study, we utilized RNAi (RNA interference) technology to knock down GH3 genes in the M9-T337 background, aiming to engineer a dwarfing and stress-tolerant apple rootstock. We found that MdGH3 RNAi plants exhibited superior morphology compared to M9-T337 under saline-alkali stress conditions, characterized by more robust root systems, increased plant height, a lower Na+/K+ ratio, and enhanced photosynthetic and antioxidant capacities. Moreover, when MdGH3 RNAi plants were used as rootstocks, the GL-3/MdGH3 RNAi plants also displayed greater plant height, root vitality, photosynthetic ability, and antioxidant capacity compared to GL-3 grafted onto M9-T337 rootstock. Taken together, our study constructed a saline-alkali-tolerant apple rootstock by knocking down MdGH3 genes.
Heat stress (HS) is a major environmental stress that inhibits plant growth and development. Plants have evolved various mechanisms to cope with heat stress, a key one being the HSF-HSP (Heat stress transcription factor-Heat shock protein) signaling pathway. HSFs can be divided into three classes: A, B, and C. In this study, we report the identification and functional characterization of a specific B2 member LdHSFB2a in Lilium davidii var. unicolor. RT-qPCR (Real-time Quantitative Polymerase Chain Reaction) analyses indicated that LdHSFB2a was highly expressed in HS-exposed leaves. LdHSFB2a was localized in the nucleus, consistent with the characterization of transcription factors. In contrast to other HSFBs, LdHSFB2a did not contain the typical B3 repression domain but exhibited transcriptional repression activity in yeast and plant cells. Transient overexpression and virus-induced gene silencing (VIGS) of LdHSFB2a in lily petals suggested that LdHSFB2a functions positively in lily thermotolerance. Consistent with the implication of LdHSFB2a function in thermotolerance, further analysis revealed that the expression levels of HSFA1, HSFA2, and MBF1c were increased as LdHSFB2a was overexpressed but reduced as LdHSFB2a was silenced. Furthermore, LdHSFB2a bound to the promoters of HSFA3 A, WRKY33, CAT2, and GLOS1. And LdHSFB2a overexpression and silencing enhanced and reduced their expressions, respectively. Therefore, we speculated that LdHSFB2a may be a coactivator that interacts with transcriptional activators to promote thermotolerance in lily by enhancing the expression of heat-responsive genes such as HSFA3 A, WRKY33, CAT2, and GLOS1.
Cellulose is synthesized by cellulose synthases (CESAs) in plasma membrane-localized complexes, which act as a central component of the cell wall and influence plant growth and defense responses. Puccinia striiformis f. sp. tritici (Pst) is an airborne fungus that causes stripe rust to seriously endanger wheat production. In this study, a CESA gene, TaCESA7, was identified to be significantly up-regulated during Pst infection in wheat (Triticum aestivum L.). TaCESA7 was localized on the plasma membrane in dimeric form, and the dimers interact to assemble into CESA complexes. Stable overexpression of TaCESA7 weakened the resistance of wheat to Pst. Knockdown of TaCESA7 by RNA interference (RNAi) and virus-induced gene silencing led to restricted hyphal spread, increased necrotic area, and simultaneously promotes reactive oxygen species (ROS) accumulation and the expression of pathogenesis-related (PR) genes. Transcriptome analysis of TaCESA7-RNAi plants revealed that the up-regulated genes were significantly enriched in the phenylpropanoid biosynthesis and plant-pathogen interaction pathways. Moreover, silencing TaCESA7 promoted the deposition of lignin and the expression of genes related to lignin synthesis. CRISPR-Cas9-mediated inactivation of TaCESA7 in wheat could confer broad-spectrum resistance against Pst without affecting agronomic traits. These findings provide valuable candidate gene resources and guidance for molecular breeding to improve the resistance of wheat to fungal disease.
Drought is a common environmental condition that significantly impairs plant growth. In response to drought, plants close their stomata to minimize transpiration and meanwhile activate many stress-responsive genes to mitigate damage. These stress-related mRNA transcripts require the assistance of RNA-binding proteins throughout their metabolic process, culminating in protein synthesis in the cytoplasm. In this study, we identified HLN1 (Hyaluronan 1), an RNA-binding protein with similarity to the animal hyaluronan-binding protein 4 / serpin mRNA binding protein 1 (HABP4/SERBP1), as crucial for plant drought tolerance. The hln1 loss-of-function mutant exhibited higher transpiration rates due to impaired stomatal closure, making it highly susceptible to drought. Drought stress increased HLN1 expression, and the protein underwent liquid–liquid phase separation (LLPS) to form mRNA-ribonucleoprotein (mRNP) condensates in the cytoplasm under osmotic stress. We identified GAD2 as a potential mRNA target of HLN1. GAD2 encodes the predominant glutamate decarboxylase synthesizing γ‐aminobutyric acid (GABA), a non-proteinogenic amino acid that modulates stomatal movement. RIP-qPCR and EMSA showed that HLN1 binds GAD2 mRNA, which promotes HLN1 condensate formation. In hln1 mutants, GAD2 transcripts were less stable, reducing steady-state mRNA levels. As a result, hln1 accumulated less GABA and exhibited impaired stomatal closure under drought. Conversely, HLN1 overexpression stabilized GAD2 mRNA, increased GABA levels, and enhanced drought tolerance in transgenic plants. GAD2 overexpression in hln1 mutants also rescued the drought-sensitive phenotypes. Overall, our study reveals a mechanism whereby HLN1 stabilizes GAD2 mRNA to enhance GABA production and drought tolerance. These findings provide novel strategies for engineering drought-resistant crops.
The Cucurbitaceae family includes a wide range of economically important fruits and vegetables; however, the laborious and highly inefficient genetic transformation efficacy of cucurbits has hindered the exploration of their gene functions. Virus-induced gene silencing (VIGS) technology, employed from the antiviral RNA silencing defense, has emerged as a viable alternative for high-throughput study of plant gene function. In this study, we successfully established a VIGS system utilizing Trichosanthes mottle mosaic virus (TrMMV), a new member of the genus Tobamovirus. We demonstrated the high efficacy and durability of gene silencing mediated by the TrMMV-VIGS vector in Nicotiana benthamiana, as well as in several cucurbit species, including Cucurbita pepo, Cucumis sativus, C. lanatus, and C. melo. The insertion of 90–400 bp fragments into the vector led to effective silencing of the target gene in both C. sativus and C. melo, with a notably higher silencing efficiency observed in C. melo. Furthermore, the TrMMV-VIGS vector induced a pronounced photobleaching phenotype in the flowers of C. melo, underscoring its potential application in functional genomic research concerning floral traits in this particular species. Taken together, the TrMMV-VIGS system developed herein will facilitate rapid and high-throughput identification of gene functions in cucurbit crops.
During interactions, pathogenic fungi are subjected to endoplasmic reticulum (ER) stress from the host plants, resulting in the activation of the unfolded protein response (UPR) pathway. We identified the bZIP transcription factor CfHac1 in C. fructicola, which is a pathogenic organism implicated in a variety of plant diseases, and we found it to be crucial for the ER stress response and pathogenicity. However, the role of CfHac1 in regulating the degradation of ER-associated misfolded proteins remains unclear. In this study, we discovered that the CfHAC1 gene regulates conidial production, appressorium formation, response to ER stress, and pathogenicity through unconventional splicing. Further research revealed that the CfHAC1 gene also affects the ubiquitination of ER-associated misfolded proteins and mediates their degradation. We further identified two ubiquitin ligase genes, CfHRD1 and CfHRD3, that exhibit significant down-regulation in the ΔCfhac1 mutant strain. Subsequent investigations revealed that the CfHAC1 gene affects CfHRD1 and CfHRD3 expression through unconventional splicing, with both genes managing the degradation of ER-associated misfolded proteins via ubiquitination and influencing C. fructicola pathogenicity. Taken together, our results reveal a mechanism by which the transcription factor CfHac1 affects the expression of the ubiquitin ligase genes CfHRD1 and CfHRD3, leading to the ubiquitination and degradation of ER-associated misfolded proteins and pathogenicity. This provides a theoretical basis for the development of novel agents targeting key genes within this pathway.
Trehalose-6-phosphate (T6P), an intermediate in trehalose metabolic pathways, is ubiquitously present in nearly all cellular organisms except vertebrates. The most well-characterized metabolic route involves its synthesis by trehalose-6-phosphate synthase (TPS) and dephosphorylation to trehalose by trehalose-6-phosphate phosphatase (TPP) in the TPS/TPP pathway. Besides, alternative trehalose metabolic pathways aslo exist. In addition to being the precursor of trehalose synthesis, T6P functions as a signal molecule regulating various biological processes. In plants, T6P inhibits SnRK1 (Sucrose-nonfermenting 1 Related Kinase 1), while in fungi, T6P primarily inhibits hexokinase and regulates glycolysis. Notably, TPS and TPP themselves also have some regulatory functions. Genetic studies reveal that deletion of TPS or TPP usually causes developmental and virulence defects in fungi, bacteria and invertebrates. Given that TPS and TPP have important biological functions in pathogenic fungi but are absent in humans and vertebrates, they are ideal targets for fungicide development. This review summarizes trehalose metabolic pathways and the multifaceted roles of T6P in plants, fungi and invertebrates, providing a comprehensive overview of its biological functions. Additionally, it discusses some reported TPS/TPP inhibitor to offer insights for pathogen control strategies.
Trail development is more prevalent as tourism develops globally. The depth effect of trail development on plant diversity and native species’ stress response via tuning flavonoids in natural ecosystems remain relatively poorly understood. We investigated the depth effects by comparing plant species diversity and flavonoid contents (of six common native species) in sampling plots plots (Rabbit Mountain Open Space, Boulder County, CO, USA) with varying distances away from trail. We found plant diversity to be lowest in plots immediately proximal to trails and highest in intermediate plots. We also found the concentrations of total flavonoids to vary significantly between plots closer and away from trails. Specifically, we found the concentrations of isoorientin and myricetin higher in plots closer to trails. On the contrary, the concentrations of vitexin and kaempferol were higher in plots away from trails. Quercetin was higher in the intermediate plots. Overall, trail development negatively impacted herbaceous plant diversity, which was evident as depth effects. The plant species responded to environmental stresses imposed by trail development through fine-tuned flavonoid accumulation.
The fungus Puccinia striiformis f. sp. tritici (Pst) is the causal agent of wheat stripe rust which constitutes a major limitation to wheat production. Cloning and applying disease-resistant genes are considered as an effective solution. Chinese wheat cultivar Xingzi 9104 (XZ9104) has exhibited durable resistance across multiple environments since its release. Through quantitative trait loci (QTL) analysis, eight QTL were found on chromosome arms 1BS, 1BL, 2AL, 2BL, 3BS, 4BL, 5BL and 7BL. YrXZ identified as 1RS.1BL translocation conferred race-specific all-stage resistance to Pst race CYR23. QYrxz.nwafu-1BL.6 and QYrxz.nwafu-3BS.7 were considered as the adult plant resistance genes Yr29 and Yr30, respectively. Notably, QYrxz.nwafu-2BL.5 accounted for 15.75–47.63% of the phenotypic variation across diverse environments and its pyramiding with Yr29 and Yr30 can confer high level of resistance. Other QTL were environment-dependent with minor effects. To clone the above resistance genes, we created a population of over 2,000 M5 mutants in XZ9104 using ethylmethane sulfonate (EMS) mutagenesis and screened various types of susceptible mutants. Using the MutIsoseq approach with five mutant lines susceptible to race CYR23, we rapid isolated a candidate gene for YrXZ encoding coiled-coil nucleotide-binding site leucine-rich repeat (CC-NBS-LRR) protein. Integrating cytological analysis, gene-based association analysis, transcriptomic profiling and virus-induced gene silencing (VIGS), we confirmed that the causal gene for YrXZ was indeed Yr9. This study demonstrated that multiple QTL with different effects contributed to the durable resistance in XZ9104. Understanding the molecular mechanisms and pathways involved in plant defense can inform future strategies for deploying resistance gene and engineering of genetic resistance against evolving diseases.
Wheat stripe rust, caused by an obligate biotrophic pathogen Puccinia striiformis f. sp. tritici (Pst) seriously threatens wheat production. Discovering and utilizing of wheat resistance genes is the most effective and economical method to control diseases. The G-type lectin receptor-like kinase (LecRLKs) involved in biotic stress perception, while their roles in wheat resistance to Pst remain elusive. In our study, we identified 398 G-type LecRKs in wheat through BLAST and HMM profiling. The transcript level of 16 random selected G-type LecRKs from each subfamily were analyzed and found TaSRLK is highly induced by avirulent Pst CYR23 infection. TaSRLK-silenced wheat plants showed reduced resistance to Pst with increased hyphal length and decreased H2O2 accumulation. Surprisingly, TaSRLK was localized to the chloroplast and can induce cell death in Nicotiana benthamiana. Further, TaSRLK was shown to interact with and phosphorylate a peroxidase TaPrx1. Importantly, TaPrx1 involved in wheat resistance to Pst through regulating reactive oxygen species (ROS) production. Together these findings demonstrate that TaSRLK positively modulates ROS-associated wheat resistance by binding with TaPrx1.
The fungicide metconazole, which acts as a sterol 14α-demethylation inhibitor (DMI), can exhibit strong inhibitory effects on Fusarium pseudograminearum. However, the resistance mechanism as well as the risk that F. pseudograminearum develops resistance to metconazole is yet to be fully assessed. In this study, metconazole displayed a mean EC50 value of 0.0559 μg/mL against 105 F. pseudograminearum isolates. Ten sensitive parental isolates were then subjected to fungicide adaptation to generate resistant mutants, with in vitro experiments subsequently highlighting the inferior fitness of the mutants. In addition, metconazole exhibited positive cross-resistance with both mefentrifluconazole and tebuconazole. Altogether, the results confirmed the low risk that F. pseudograminearum develops resistance to metconazole. Finally, a mutation genotype (M151T) was identified in FpCYP51B, with the mutants also overexpressing the FpCYP51 genes. Subsequent molecular docking and transformation-based experiments indicated that M151T substitution and overexpression in FpCYP51 genes conferred resistance to metconazole in F. pseudograminearum.
Plant peptides play crucial roles in various biological processes, including stress responses. This study investigates the functions of plant peptides in response to different adversity stresses, focusing on drought, salt, high temperature, and other environmental challenges. In drought conditions, specific peptides such as CLE25 and CLE9 were found to regulate stomatal closure and root architecture to enhance the efficiency of water utilization. Salt stress induces the expression of CAPE1 and CEP3, which are involved in ion homeostasis and osmoregulation, thereby contributing to salt tolerance in plants. Heat stress triggers the expression of peptides such as CEL45, which contributes to the heat tolerance of cells. Besides, we have also verified a new class of non-conventional peptides, and a large number of non-conventional peptides have been identified in rice seedlings. Understanding the origin and functions of these peptides presents both challenges and opportunities for developing stress-resistant crops. Future research should focus on elucidating the precise molecular mechanisms of peptide-mediated stress responses and exploring their potential applications in agriculture and biotechnology.
Receptor-like cytoplasmic kinases (RLCKs) function as a central player in plant receptor kinases-mediated signaling, which regulate various aspects of plant immunity and growth. RLCKs receive signals from pattern recognition receptors (PRRs) to activate pattern-triggered immunity (PTI), including reactive oxygen species (ROS) production, Ca2+ influx, mitogen-activated protein kinase (MAPK) cascades, cellulose synthesis, phosphatidic acid (PA) production, hormone synthesis and signaling, and transcriptional remodeling. Besides, RLCK also participate in effector-triggered immunity (ETI) and the interplay between ETI and PTI. Increasing evidences show that much more RLCKs are involved in plant immune responses and form an intertwined signaling network. This review summarizes the recent findings about RLCKs-mediated signaling in plant immune responses and emphasizes signal convergence and divergence involved which provides new insights into the RLCKs signaling network in diverse biological processes.
Aphids are highly destructive agricultural pests characterized by complex life cycles and phenotypic variability, facilitating their adaptation to diverse climates and host plants. Their feeding behavior leads to plant deformation, wilting, stunted growth, disease transmission, and significant yield losses. Given the economic risks aphids pose, regular updates on their seasonal behaviors, adaptive mechanisms, and destructive activities are critical for improving management strategies to mitigate crop losses. This review comprehensively synthesizes recent studies on aphids as plant pests, the extrinsic factors influencing their life cycles, and the intricate interactions between aphids and their hosts. It also highlights recent advancements in biological control measures, including natural enemies, antibiosis, and antixenosis. Additionally, we explore plant defense mechanisms against aphids, focusing on the roles of cell wall components such as lignin, pectin and callose deposition and the genetic regulations underlying these defenses. Aphids, however, can evolve specialized strategies to overcome general plant defenses, prompting the development of targeted mechanisms in plants, such as the use of resistance (R) genes against specific aphid species. Additionally, plant pattern recognition receptors (PRRs) recognize compounds in aphid saliva, which triggers enhanced phloem sealing and more focused immune responses. This work enhances understanding of aphid–plant interaction and plant resistance and identifies key research gaps for future studies.