Bacillus cereus NJ01 induces SA- and ABA-mediated immunity against bacterial pathogens through the EDS1-WRKY18 module.

Emerging evidence suggests a beneficial role of rhizobacteria in ameliorating plant disease resistance in an environment-friendly way. In this study, we characterize a rhizobacterium, Bacillus cereus NJ01, that enhances bacterial pathogen resistance in rice and Arabidopsis. Transcriptome analyses show that root inoculation of NJ01 induces the expression of salicylic acid (SA)- and abscisic acid (ABA)-related genes in Arabidopsis leaves. Genetic evidence showed that EDS1, PAD4, and WRKY18 are required for B. cereus NJ01-induced bacterial resistance. An EDS1-PAD4 complex interacts with WRKY18 and enhances its DNA binding activity. WRKY18 directly binds to the W box in the promoter region of the SA biosynthesis gene ICS1 and ABA biosynthesis genes NCED3 and NCED5 and contributes to the NJ01-induced bacterial resistance. Taken together, our findings indicate a role of the EDS1/PAD4-WRKY18 complex in rhizobacteria-induced disease resistance.

OsLRR-RLP2 Gene Regulates Immunity to Magnaporthe oryzae in Japonica Rice.

Rice is an important cereal crop worldwide, the growth of which is affected by rice blast disease, caused by the fungal pathogen Magnaporthe oryzae. As climate change increases the diversity of pathogens, the disease resistance genes (R genes) in plants must be identified. The major blast-resistance genes have been identified in indica rice varieties; therefore, japonica rice varieties with R genes now need to be identified. Because leucine-rich repeat (LRR) domain proteins possess R-gene properties, we used bioinformatics analysis to identify the rice candidate LRR domain receptor-like proteins (OsLRR-RLPs). OsLRR-RLP2, which contains six LRR domains, showed differences in the DNA sequence, containing 43 single-nucleotide polymorphisms (SNPs) in indica and japonica subpopulations. The results of the M. oryzae inoculation analysis indicated that indica varieties with partial deletion of OsLRR-RLP2 showed susceptibility, whereas japonica varieties with intact OsLRR-RLP2 showed resistance. The oslrr-rlp2 mutant, generated using clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9), showed increased pathogen susceptibility, whereas plants overexpressing this gene showed pathogen resistance. These results indicate that OsLRR-RLP2 confers resistance to rice, and OsLRR-RLP2 may be useful for breeding resistant cultivars.

RiceProteomeDB (RPDB): a user-friendly database for proteomics data storage, retrieval, and analysis.

Rice, feeding a significant portion of the world, poses unique proteomic challenges critical to agricultural research and global food security. The complexity of the rice proteome, influenced by various genetic and environmental factors, demands specialized analytical approaches for effective study. The central challenges in rice proteomics lie in developing custom methods suited to the unique aspects of rice biology. These include data preprocessing, method selection, and result validation, all of which are essential for advancing rice research. Our aim is to decode these proteomic intricacies to facilitate breakthroughs in strain improvement, disease resistance, and yield optimization, all vital for combating global food insecurity. To achieve this, we have created the RiceProteomeDB (RPDB), a React + Django database, offering a streamlined and comprehensive platform for the analysis of rice proteomics data. RiceProteomeDB (RPDB) simplifies proteomics data management and analysis. It offers features for data organization, preprocessing, method selection, result validation, and data sharing. Researchers can access processed rice proteomics data, conduct analyses, and explore experimental conditions. The user-friendly web interface enhances navigation and interaction. RPDB fosters collaboration by enabling data sharing and proper acknowledgment of sources, contributing to proteomics research and knowledge dissemination. Availability and implementation: Web application: http://riceproteome.plantprofile.net/ . The web application's source code, user's manual, and sample data: https://github.com/dongu7610/Riceproteome .

Integrated "-omics" analysis highlights the role of brassinosteroid signaling and antioxidant machinery underlying improved rice seed longevity during artificial aging treatment.

Seed longevity is a critical characteristic in agriculture, yet the specific genes/proteins responsible for this trait and the molecular mechanisms underlying reduced longevity during seed aging remain largely elusive. Here we report the comparative proteome and metabolome profiling of three rice cultivars exhibiting varying degrees of aging tolerance: Dharial, an aging-tolerant cultivar; Ilmi, an aging-sensitive cultivar; and A2, a moderately aging-tolerant cultivar developed from the crossbreeding of Dharial and Ilmi. Artificial aging treatment (AAT) markedly reduced the germination percentage and enhanced the activities of antioxidant enzymes in all the cultivars. Further, proteomics results showed a key role of the ubiquitin (Ub)-proteasome pathway in the degradation of damaged proteins during AAT while other proteases were majorly reduced. In addition, proteins associated with energy production and protein synthesis were strongly reduced in Ilmi while these were majorly increased in A2 and Dharial. These, along with metabolomics results, suggest that Ub-proteasome mediated protein degradation during AAT results in the accumulation of free amino acids in Ilmi while tolerant cultivars potentially utilize those for energy production and synthesis of stress-related proteins, especially hsp20/alpha-crystallin family protein. Additionally, both Dharial and A2 seem to activate brassinosteroid signaling and suppress jasmonate signaling which initiates a signaling cascade that allows accumulation of enzymatic and non-enzymatic antioxidants for efficient detoxification of aging-induced ROS. Taken together, these results provide an in-depth understanding of the aging-induced changes in rice seeds and highlight key pathways responsible for maintaining seed longevity during AAT.

Disruption of phosphofructokinase activity and aerobic glycolysis in human bronchial epithelial cells by atmospheric ultrafine particulate matter.

Exposure to ambient ultrafine particulate matter (UPM) causes respiratory disorders; however, the underlying molecular mechanisms remain unclear. In this study, we synthesized simulated UPM (sUPM) with controlled physicochemical properties using the spark-discharge method. Subsequently, we investigated the biological effects of sUPM using BEAS-2B human bronchial epithelial cells (HBECs) and a mouse intratracheal instillation model. High throughput RNA-sequencing and bioinformatics analyses revealed that dysregulation of the glycolytic metabolism is involved in the inhibited proliferation and survival of HBECs by sUPM treatment. Furthermore, signaling pathway and enzymatic analyses showed that the treatment of BEAS-2B cells with sUPM induces the inactivation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, also known as AKT), resulting in the downregulation of phosphofructokinase 2 (PFK2) S483 phosphorylation, PFK enzyme activity, and aerobic glycolysis in HBECs in an oxidative stress-independent manner. Additionally, intratracheal instillation of sUPM reduced the phosphorylation of ERK, AKT, and PFK2, decreased proliferation, and increased the apoptosis of bronchial epithelial cells in mice. The findings of this study imply that UPM induces pulmonary toxicity by disrupting aerobic glycolytic metabolism in lung epithelial cells, which can provide novel insights into the toxicity mechanisms of UPM and strategies to prevent their toxic effects.

Quantitative Proteomic Analysis Deciphers the Molecular Mechanism for Endosperm Nuclear Division in Early Rice Seed Development.

Understanding the molecular mechanisms underlying early seed development is important in improving the grain yield and quality of crop plants. We performed a comparative label-free quantitative proteomic analysis of developing rice seeds for the WT and osctps1-2 mutant, encoding a cytidine triphosphate synthase previously reported as the endospermless 2 (enl2) mutant in rice, harvested at 0 and 1 d after pollination (DAP) to understand the molecular mechanism of early seed development. In total, 5231 proteins were identified, of which 902 changed in abundance between 0 and 1 DAP seeds. Proteins that preferentially accumulated at 1 DAP were involved in DNA replication and pyrimidine biosynthetic pathways. Notably, an increased abundance of OsCTPS1 was observed at 1 DAP; however, no such changes were observed at the transcriptional level. We further observed that the inhibition of phosphorylation increased the stability of this protein. Furthermore, in osctps1-2, minichromosome maintenance (MCM) proteins were significantly reduced compared with those in the WT at 1 DAP, and mutations in OsMCM5 caused defects in seed development. These results highlight the molecular mechanisms underlying early seed development in rice at the post-transcriptional level.

Dataset on post-translational modifications proteome analysis of MSP1-overexpressing rice leaf proteins.

The data reported here are associated with the article entitled "Analysis of Post-Translational Modification Dynamics Unveiled Novel Insights into Rice Responses to MSP1" [1]. pathogen-associated molecular pattern (PAMP) -triggered immunity (PTI) serves as the fundamental defense mechanism in plants, providing innate protection against pathogen invasion. The fungus Magnaporthe oryzae (M. oryzae) secretes MSP1, a protein recognized as a PAMP that induces PTI responses in rice. However, the comprehensive characterization of MSP1-induced post-translational modifications (PTMs) and their contribution to PTI responses remains elusive thus far. In this manuscript, we report the analysis of the phosphoproteome, ubiquitinome, and acetylproteome to investigate the alterations in MSP1-induced changes in these PTMs in MSP1 overexpressed and wild-type rice, utilizing the QExactiveTM Orbitrap High-Resolution Mass Spectrometer [1]. Our data primarily focuses on unraveling the PTMs of MSP1-overexpressing transgenic rice, with the goal of elucidating MSP1-induced signaling cascades and deciphering their regulatory mechanisms.

Comparative Proteome-wide Characterization of Three Different Tissues of High-Protein Mutant and Wild Type Unravels Protein Accumulation Mechanisms in Rice Seeds.

Improving the proteins and amino acid contents of rice seeds is one of the prime objectives of plant breeders. We recently developed an EMS mutant/high-protein mutant (HPM) of rice that exhibits 14.8% of the total protein content as compared to its parent Dharial (wild-type), which shows only 9.3% protein content in their mature seeds. However, the mechanisms underlying the higher protein accumulation in these HPM seeds remain largely elusive. Here, we utilized high-throughput proteomics to examine the differences in the proteome profiles of the embryo, endosperm, and bran tissues of Dharial and HPM seeds. Utilizing a label-free quantitative proteomic and subsequent functional analyses of the identified proteins revealed that nitrogen compound biosynthesis, intracellular transport, protein/amino acid synthesis, and photosynthesis-related proteins were specifically enriched in the endosperm and bran of the high-protein mutant seed. Our data have uncovered proteome-wide changes highlighting various functions of metabolic pathways associated with protein accumulation in rice seeds.

Analysis of post-translational modification dynamics unveiled novel insights into Rice responses to MSP1.

Magnaporthe oryzae snodprot1 homologous protein (MSP1) is known to function as a pathogen-associated molecular pattern (PAMP) and trigger PAMP-triggered immunity (PTI) in rice including induction of programmed cell death and expression of defense-related genes. The involvement of several post-translational modifications (PTMs) in the regulation of plant immune response, especially PTI, is well established, however, the information on the regulatory roles of these PTMs in response to MSP1-induced signaling is currently elusive. Here, we report the phosphoproteome, ubiquitinome, and acetylproteome to investigate the MSP1-induced PTMs alterations in MSP1 overexpressed and wild-type rice. Our analysis identified a total of 4666 PTMs-modified sites in rice leaves including 4292 phosphosites, 189 ubiquitin sites, and 185 acetylation sites. Among these, the PTM status of 437 phosphorylated, 53 ubiquitinated, and 68 acetylated peptides was significantly changed by MSP1. Functional annotation of MSP1 modulated peptides by MapMan analysis revealed that these were majorly associated with cellular immune responses including signaling, transcription factors, DNA and RNA regulation, and protein metabolism, among others. Taken together, our study provides novel insights into post-translational mediated regulation of rice proteins in response to M. oryzae secreted PAMP which help in understanding the molecular mechanism of MSP1-induced signaling in rice in greater detail. SIGNIFICANCE: The research investigates the effect of overexpression of MSP1 protein in rice leaves on the phosphoproteome, acetylome, and ubiquitinome. The study found that MSP1 is involved in rice protein phosphorylation, particularly in signaling pathways, and identified a key component, PTAC16, in MSP1-induced signaling. The analysis also revealed MSP1's role in protein degradation and modification by inducing ubiquitination of the target rice proteins. The research identified potential kinases involved in the phosphorylation of rice proteins, including casein kinase II, 14-3-3 domain binding motif, ß-adrenergic receptor kinase, ERK1,2 kinase substrate motif, and casein kinase I motifs. Overall, the findings provide insights into the molecular mechanisms underlying of MSP1 induced signaling in rice which may have implications for improving crop yield and quality.

Rice pollen-specific OsRALF17 and OsRALF19 are essential for pollen tube growth.

Pollen tube growth is essential for successful double fertilization, which is critical for grain yield in crop plants. Rapid alkalinization factors (RALFs) function as ligands for signal transduction during fertilization. However, functional studies on RALF in monocot plants are lacking. Herein, we functionally characterized two pollen-specific RALFs in rice (Oryza sativa) using multiple clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9-induced loss-of-function mutants, peptide treatment, expression analyses, and tag reporter lines. Among the 41 RALF members in rice, OsRALF17 was specifically expressed at the highest level in pollen and pollen tubes. Exogenously applied OsRALF17 or OsRALF19 peptide inhibited pollen tube germination and elongation at high concentrations but enhanced tube elongation at low concentrations, indicating growth regulation. Double mutants of OsRALF17 and OsRALF19 (ralf17/19) exhibited almost full male sterility with defects in pollen hydration, germination, and tube elongation, which was partially recovered by exogenous treatment with OsRALF17 peptide. This study revealed that two partially functionally redundant OsRALF17 and OsRALF19 bind to Oryza sativa male-gene transfer defective 2 (OsMTD2) and transmit reactive oxygen species signals for pollen tube germination and integrity maintenance in rice. Transcriptomic analysis confirmed their common downstream genes, in osmtd2 and ralf17/19. This study provides new insights into the role of RALF, expanding our knowledge of the biological role of RALF in regulating rice fertilization.

The Phytophthora nucleolar effector Pi23226 targets host ribosome biogenesis to induce necrotrophic cell death.

Pathogen effectors target diverse subcellular organelles to manipulate the plant immune system. Although the nucleolus has emerged as a stress marker and several effectors are localized in the nucleolus, the roles of nucleolar-targeted effectors remain elusive. In this study, we showed that Phytophthora infestans infection of Nicotiana benthamiana results in nucleolar inflation during the transition from the biotrophic to the necrotrophic phase. Multiple P. infestans effectors were localized in the nucleolus: Pi23226 induced cell death in N. benthamiana and nucleolar inflation similar to that observed in the necrotrophic stage of infection, whereas its homolog Pi23015 and a deletion mutant (Pi23226ΔC) did not induce cell death or affect nucleolar size. RNA immunoprecipitation and individual-nucleotide-resolution UV crosslinking and immunoprecipitation sequencing analysis indicated that Pi23226 bound to the 3' end of 25S rRNA precursors, resulting in accumulation of unprocessed 27S pre-rRNAs. The nucleolar stress marker NAC082 was strongly upregulated under Pi23226-expressing conditions. Pi23226 subsequently inhibited global protein translation in host cells by interacting with ribosomes. Pi23226 enhanced P. infestans pathogenicity, indicating that Pi23226-induced ribosome malfunction and cell death were beneficial for pathogenesis in the host. Our results provide evidence for the molecular mechanism underlying RNA-binding effector activity in host ribosome biogenesis and lead to new insights into the nucleolar action of effectors in pathogenesis.

Proteome profiling highlights mechanisms underlying pigment and tocopherol accumulation in red and black rice seeds.

Rice is a major component of the human diet and feeds more than 50 million people across the globe. We previously developed two pigmented rice cultivars, Super-hongmi (red seeds) and Super-jami (black seeds), that are highly rich in antioxidants and exhibit high levels of radical scavenging activities. However, the molecular mechanism underlying the accumulation of pigments and different antioxidants in these rice cultivars remains largely elusive. Here, we report the proteome profiles of mature Super-hongmi and Super-jami seeds, and compared them with the Hopum (white seeds) using a label-free quantitative proteomics approach. This approach led to the identification of 5127 rice seed proteins of which 1628 showed significant changes in the pigmented rice cultivar(s). The list of significantly modulated proteins included a phytoene desaturase (PDS3) which suggested accumulation of ζ-carotene in red seeds while the black seeds seem to accumulate more of anthocyanins because of the higher abundance of dihydroflavonol 4-reductase. Moreover, proteins associated with lignin and tocopherol biosynthesis were highly increased in both red and black cultivars. Taken together, these data report the seed proteome of three different colored rice seeds and identify novel components associated with pigment accumulation in rice.

A Proteomics Insight into Advancements in the Rice-Microbe Interaction.

Rice is one of the most-consumed foods worldwide. However, the productivity and quality of rice grains are severely constrained by pathogenic microbes. Over the last few decades, proteomics tools have been applied to investigate the protein level changes during rice-microbe interactions, leading to the identification of several proteins involved in disease resistance. Plants have developed a multi-layered immune system to suppress the invasion and infection of pathogens. Therefore, targeting the proteins and pathways associated with the host's innate immune response is an efficient strategy for developing stress-resistant crops. In this review, we discuss the progress made thus far with respect to rice-microbe interactions from side views of the proteome. Genetic evidence associated with pathogen-resistance-related proteins is also presented, and challenges and future perspectives are highlighted in order to understand the complexity of rice-microbe interactions and to develop disease-resistant crops in the future.

Examining the Effect of Notocactus ottonis Cold Vacuum Isolated Plant Cell Extract on Hair Growth in C57BL/6 Mice Using a Combination of Physiological and OMICS Analyses.

The biological and psychological importance of hair is recognized worldwide. Molecules that can promote the activation of hair follicle stem cells and the initiation of the growth phase have been subjects of research. Clarifying how hair regeneration is regulated may help to provide hair loss treatments, including cosmetic and even psychological interventions. We examined the hair-growing effects of a cell extract (CE) obtained from cactus Notocactus ottonis by the cold vacuum extraction protocol, by investigating its hair-growing effects, relevant mechanisms, and potential factors therein. Using male C57BL/6 mice, vehicle control (VC: propylene glycol: ethanol: water), MXD (minoxidil, positive control), and N. ottonis CE (N-CE, experimental) were applied topically to the backs of mice. The results showed that MXD and N-CE were more effective in promoting hair growth than VC. An increase in number of hair follicles was observed with N-CE in hematoxylin-eosin-stained skin tissue. The metabolite composition of N-CE revealed the presence of growth-promoting factors. Using mouse back whole-skin tissue samples, whole-genome DNA microarray (4 × 44 K, Agilent) and proteomics (TMT-based liquid chromatography-tandem mass spectrometry) analyses were carried out, suggesting the molecular factors underlying hair-promoting effects of N-CE. This study raises the possibility of using the newly described N. ottonis CE as a hair-growth-promoting agent.

OMICS Analyses Unraveling Related Gene and Protein-Driven Molecular Mechanisms Underlying PACAP 38-Induced Neurite Outgrowth in PC12 Cells.

The study aimed to understand mechanism/s of neuronal outgrowth in the rat adrenal-derived pheochromocytoma cell line (PC12) under pituitary adenylate cyclase-activating polypeptide (PACAP) treatment. Neurite projection elongation was suggested to be mediated via Pac1 receptor-mediated dephosphorylation of CRMP2, where GSK-3ß, CDK5, and Rho/ROCK dephosphorylated CRMP2 within 3 h after addition of PACAP, but the dephosphorylation of CRMP2 by PACAP remained unclear. Thus, we attempted to identify the early factors in PACAP-induced neurite projection elongation via omics-based transcriptomic (whole genome DNA microarray) and proteomic (TMT-labeled liquid chromatography-tandem mass spectrometry) analyses of gene and protein expression profiles from 5-120 min after PACAP addition. The results revealed a number of key regulators involved in neurite outgrowth, including known ones, called 'Initial Early Factors', e.g., genes Inhba, Fst, Nr4a1,2,3, FAT4, Axin2, and proteins Mis12, Cdk13, Bcl91, CDC42, including categories of 'serotonergic synapse, neuropeptide and neurogenesis, and axon guidance'. cAMP signaling and PI3K-Akt signaling pathways and a calcium signaling pathway might be involved in CRMP2 dephosphorylation. Cross-referencing previous research, we tried to map these molecular components onto potential pathways, and we may provide important new information on molecular mechanisms of neuronal differentiation induced by PACAP. Gene and protein expression data are publicly available at NCBI GSE223333 and ProteomeXchange, identifier PXD039992.

Proteomic Analysis Reveals a Critical Role of the Glycosyl Hydrolase 17 Protein in Panax ginseng Leaves under Salt Stress.

Ginseng, an important crop in East Asia, exhibits multiple medicinal and nutritional benefits because of the presence of ginsenosides. On the other hand, the ginseng yield is severely affected by abiotic stressors, particularly salinity, which reduces yield and quality. Therefore, efforts are needed to improve the ginseng yield during salinity stress, but salinity stress-induced changes in ginseng are poorly understood, particularly at the proteome-wide level. In this study, we report the comparative proteome profiles of ginseng leaves at four different time points (mock, 24, 72, and 96 h) using a label-free quantitative proteome approach. Of the 2484 proteins identified, 468 were salt-responsive. In particular, glycosyl hydrolase 17 (PgGH17), catalase-peroxidase 2, voltage-gated potassium channel subunit beta-2, fructose-1,6-bisphosphatase class 1, and chlorophyll a-b binding protein accumulated in ginseng leaves in response to salt stress. The heterologous expression of PgGH17 in Arabidopsis thaliana improved the salt tolerance of transgenic lines without compromising plant growth. Overall, this study uncovers the salt-induced changes in ginseng leaves at the proteome level and highlights the critical role of PgGH17 in salt stress tolerance in ginseng.

TMT-based quantitative proteome data of MSP1 overexpressed rice.

Data reported here is associated with the article entitled "TMT-based quantitative membrane proteomics identified pattern recognition receptors (PRRs) potentially involved in the perception of MSP1 in rice leaves" [1]. PAMP-triggered immunity (PTI) constitutes the first layer of plant innate immunity against pathogen infection. M. oryzae secreted protein MSP1 has been identified as a PAMP which induces PTI responses in rice. However, identification of PRRs involved in the recognition of MSP1 has not been achieved so far. In this manuscript, we carried out comprehensive proteomic profiling to investigate the potential PRRs and MSP1 induced signaling cascades using MSP1 overexpressed transgenic rice by TMT-labeling based quantitative analysis with QExactiveTM Orbitrap High-Resolution Mass Spectrometer [1].

Phytochemistry of ginsenosides: Recent advancements and emerging roles.

Ginsenosides, a group of tetracyclic saponins, accounts for the nutraceutical and pharmaceutical relevance of the ginseng (Panax sp.) herb. Owing to the associated therapeutic potential of ginsenosides, their demand has been increased significantly in the last two decades. However, a slow growth cycle, low seed production, and long generation time of ginseng have created a gap between the demand and supply of ginsenosides. The biosynthesis of ginsenosides involves an intricate network of pathways with multiple oxidation and glycosylation reactions. However, the exact functions of some of the associated genes/proteins are still not completely deciphered. Moreover, ginsenoside estimation and extraction using analytical techniques are not feasible with high efficiency. The present review is a step forward in recapitulating the comprehensive aspects of ginsenosides including their distribution, structural diversity, biotransformation, and functional attributes in both plants and animals including humans. Moreover, ginsenoside biosynthesis in the potential plant sources and their metabolism in the human body along with major regulators and stimulators affecting ginsenoside biosynthesis have also been discussed. Furthermore, this review consolidates biotechnological interventions to enhance the biosynthesis of ginsenosides in their potential sources and advancements in the development of synthetic biosystems for efficient ginsenoside biosynthesis to meet their rising industrial demands.

Homeobox transcription factors OsZHD1 and OsZHD2 induce inflorescence meristem activity at floral transition in rice.

Floral transition starts in the leaves when florigens respond to various environmental and developmental factors. Among several regulatory genes that are preferentially expressed in the inflorescence meristem during the floral transition, this study examines the homeobox genes OsZHD1 and OsZHD2 for their roles in regulating this transition. Although single mutations in these genes did not result in visible phenotype changes, double mutations in these genes delayed flowering. Florigen expression was not altered in the double mutants, indicating that the delay was due to a defect in florigen signaling. Morphological analysis of shoot apical meristem at the early developmental stage indicated that inflorescence meristem development was significantly delayed in the double mutants. Overexpression of ZHD2 causes early flowering because of downstream signals after the generation of florigens. Expression levels of the auxin biosynthesis genes were reduced in the mutants and the addition of indole-3-acetic acid recovered the defect in the mutants, suggesting that these homeobox genes play a role in auxin biosynthesis. A rice florigen, RICE FLOWERING LOCUS T 1, binds to the promoter regions of homeobox genes. These results indicate that florigens stimulate the expression of homeobox genes, enhancing inflorescence development in the shoot apex.

TMT-based quantitative membrane proteomics identified PRRs potentially involved in the perception of MSP1 in rice leaves.

Pathogen-associated molecular patterns (PAMPs) play a key role in triggering PAMPs triggered immunity (PTI) in plants. In the case of the rice-Magnaporthe oryzae pathosystem, fewer PAMPs and their pattern recognition receptors (PRRs) have been characterized. Recently, a M. oryzae snodprot1 homolog protein (MSP1) has been identified that functions as PAMP and triggering the PTI responses in rice. However, the molecular mechanism underlying MSP1-induced PTI is currently elusive. Therefore, we generated MSP1 overexpressed transgenic lines of rice, and a tandem mass tag (TMT)-based quantitative membrane proteomic analysis was employed to decipher the potential MSP1-induced signaling in rice using total cytosolic as well as membrane protein fractions. This approach led to the identification of 8033 proteins of which 1826 were differentially modulated in response to overexpression of MSP1 and/or exogenous jasmonic acid treatment. Of these, 20 plasma membrane-localized receptor-like kinases (RLKs) showed increased abundance in MSP1 overexpression lines. Moreover, activation of proteins related to the protein degradation and modification, calcium signaling, redox, and MAPK signaling was observed in transgenic lines expressing MSP1 in the apoplast. Taken together, our results identified potential PRR candidates involved in MSP1 recognition and suggested the overview mechanism of the MSP1-induced PTI signaling in rice leaves. SIGNIFICANCE: In plants, recognition of pathogen pathogen-derived molecules, such as PAMPs, by plant plant-derived PRRs has an essential role for in the activation of PTI against pathogen invasion. Typically, PAMPs are recognized by plasma membrane (PM) localized PRRs, however, identifying the PM-localized PRR proteins is challenging due to their low abundance. In this study, we performed an integrated membrane protein enrichment by microsomal membrane extraction (MME) method and subsequent TMT-labeling-based quantitative proteomic analysis using MSP1 overexpressed rice. Based on these results, we successfully identified various intracellular and membrane membrane-localized proteins that participated in the MSP1-induced immune response and characterized the potential PM-localized PRR candidates in rice.