Plant Disease Resistance-Related Signaling Pathways: Recent Progress and Future Prospects

Intricacies of plants' innate immune responses and their dynamic relationship with fungi: A review

The role of the plant innate immune system in the defense and symbiosis processes becomes integral in a complex network of interactions between plants and fungi. An understanding of the molecular characterization of the plant innate immune system is crucial because it constitutes plants' self-defense shield against harmful fungi, while creating mutualistic relationships with beneficial fungi. Due to the plant-induced awareness and their complexity of interaction with fungi, sufficient assessment of the participation of the plant innate immune system in ecological balance, agriculture, and maintenance of an infinite ecosystem is mandatory. Given the current global challenge, such as the surge of plant-infectious diseases, and pursuit of sustainable forms of agriculture; it is imperative to understand the molecular language of communication between plants and fungi. That knowledge can be practically used in diverse areas, e.g., in agriculture, new tactics may be sought after to try new methods that boost crop receptiveness against fungal pathogens and reduce the dependence on chemical management. Also, it could boost sustainable agricultural practices via enhancing mycorrhizal interactions that promote nutrient absorption and optimum cropping with limited exposure of environmental contamination. Moreover, this review offers insights that go beyond agriculture and can be manipulated to boost plant conservation, environmental restoration, and quality understanding of host-pathogen interactions. Consequently, this specific review paper has offered a comprehensive view of the complex plant innate immune-based responses with fungi and the mechanisms in which they interact.

CaIAA2-CaARF9 module mediates the trade-off between pepper growth and immunity

To challenge the invasion of various pathogens, plants re-direct their resources from plant growth to an innate immune defence system. However, the underlying mechanism that coordinates the induction of the host immune response and the suppression of plant growth remains unclear. Here we demonstrate that an auxin response factor, CaARF9, has dual roles in enhancing the immune resistance to Ralstonia solanacearum infection and in retarding plant growth by repressing the expression of its target genes as exemplified by Casmc4, CaLBD37, CaAPK1b and CaRROP1. The expression of these target genes not only stimulates plant growth but also negatively impacts pepper resistance to R. solanacearum. Under normal conditions, the expression of Casmc4, CaLBD37, CaAPK1b and CaRROP1 is active when promoter-bound CaARF9 is complexed with CaIAA2. Under R. solanacearum infection, however, degradation of CaIAA2 is triggered by SA and JA-mediated signalling defence by the ubiquitin-proteasome system, which enables CaARF9 in the absence of CaIAA2 to repress the expression of Casmc4, CaLBD37, CaAPK1b and CaRROP1 and, in turn, impeding plant growth while facilitating plant defence to R. solanacearum infection. Our findings uncover an exquisite mechanism underlying the trade-off between plant growth and immunity mediated by the transcriptional repressor CaARF9 and its deactivation when complexed with CaIAA2.

Physiological and transcriptomic analyses reveal the regulatory mechanisms of Anoectochilus roxburghii in response to high-temperature stress

BACKGROUND

High temperatures significantly affect the growth, development, and yield of plants. Anoectochilus roxburghii prefers a cool and humid environment, intolerant of high temperatures. It is necessary to enhance the heat tolerance of A. roxburghii and breed heat-tolerant varieties. Therefore, we studied the physiological indexes and transcriptome of A. roxburghii under different times of high-temperature stress treatments.

RESULTS

Under high-temperature stress, proline (Pro), H2O2 content increased, then decreased, then increased again, catalase (CAT) activity increased continuously, peroxidase (POD) activity decreased rapidly, then increased, then decreased again, superoxide dismutase (SOD) activity, malondialdehyde (MDA), and soluble sugars (SS) content all decreased, then increased, and chlorophyll and soluble proteins (SP) content increased, then decreased. Transcriptomic investigation indicated that a total of 2740 DEGs were identified and numerous DEGs were notably enriched for "Plant-pathogen interaction" and "Plant hormone signal transduction". We identified a total of 32 genes in these two pathways that may be the key genes for resistance to high-temperature stress in A. roxburghii.

CONCLUSIONS

To sum up, the results of this study provide a reference for the molecular regulation of A. roxburghii's tolerance to high temperatures, which is useful for further cultivation of high-temperature-tolerant A. roxburghii varieties.

Anti-mildew and fresh-keeping effect of Lactiplantibacillus paraplantarum P3 cell-free supernatant on fresh in-shell peanuts during storage process

Lactiplantibacillus paraplantarum P3 (L. paraplantarum P3) cell-free supernatant (CFS) with good antifungal effect was sprayed on fresh in-shell peanuts stored at 5 °C and 30 °C to explore its effect on the microorganisms and quality of fresh in-shell peanuts during storage process. Results showed that L. paraplantarum P3 CFS effectively maintained good quality of fresh in-shell peanuts by not only reducing fungi amount and the mildew rate, but also improving the morphology, color and flavor. Besides, L. paraplantarum P3 CFS activated plant mitogen-activated protein kinase signaling pathway and plant hormone signaling pathway to produce more ethylene, gibberellin regulatory proteins and other substances to enhance plant resistance to pathogenic microorganisms. L. paraplantarum P3 CFS could also induce the biosynthesis of glycerophospholipid and arginine to increase the stress resistance of fresh peanuts. This study provides research data for the application of L. paraplantarum P3 CFS in the preservation and antimildew of fresh in-shell peanuts.

Endogenous Hormone Levels and Transcriptomic Analysis Reveal the Mechanisms of Bulbil Initiation in Pinellia ternata

Pinellia ternata is a medicinal plant that has important pharmacological value, and the bulbils serve as the primary reproductive organ; however, the mechanisms underlying bulbil initiation remain unclear. Here, we characterized bulbil development via histological, transcriptomic, and targeted metabolomic analyses to unearth the intricate relationship between hormones, genes, and bulbil development. The results show that the bulbils initiate growth from the leaf axillary meristem (AM). In this stage, jasmonic acid (JA), abscisic acid (ABA), isopentenyl adenosine (IPA), and salicylic acid (SA) were highly enriched, while indole-3-acetic acid (IAA), zeatin, methyl jasmonate (MeJA), and 5-dexoxystrigol (5-DS) were notably decreased. Through OPLS-DA analysis, SA has emerged as the most crucial factor in initiating and positively regulating bulbil formation. Furthermore, a strong association between IPA and SA was observed during bulbil initiation. The transcriptional changes in IPT (Isopentenyltransferase), CRE1 (Cytokinin Response 1), A-ARR (Type-A Arabidopsis Response Regulator), B-ARR (Type-B Arabidopsis Response Regulator), AUX1 (Auxin Resistant 1), ARF (Auxin Response Factor), AUX/IAA (Auxin/Indole-3-acetic acid), GH3 (Gretchen Hagen 3), SAUR (Small Auxin Up RNA), GA2ox (Gibberellin 2-oxidase), GA20ox (Gibberellin 20-oxidase), AOS (Allene oxide synthase), AOC (Allene oxide cyclase), OPR (Oxophytodienoate Reductase), JMT (JA carboxy l Methyltransferase), COI1 (Coronatine Insensitive 1), JAZ (Jasmonate ZIM-domain), MYC2 (Myelocytomatosis 2), D27 (DWARF27), SMAX (Suppressor of MAX2), PAL (Phenylalanine Ammonia-Lyase), ICS (Isochorismate Synthase), NPR1 (Non-expressor of Pathogenesis-related Genes1), TGA (TGACG Sequence-specific Binding), PR-1 (Pathogenesis-related), MCSU (Molybdenium Cofactor Sulfurase), PP2C (Protein Phosphatase 2C), and SnRK (Sucrose Non-fermenting-related Protein Kinase 2) were highly correlated with hormone concentrations, indicating that bulbil initiation is coordinately controlled by multiple phytohormones. Notably, eight TFs (transcription factors) that regulate AM initiation have been identified as pivotal regulators of bulbil formation. Among these, WUS (WUSCHEL), CLV (CLAVATA), ATH1 (Arabidopsis Thaliana Homeobox Gene 1), and RAX (Regulator of Axillary meristems) have been observed to exhibit elevated expression levels. Conversely, LEAFY demonstrated contrasting expression patterns. The intricate expression profiles of these TFs are closely associated with the upregulated expression of KNOX(KNOTTED-like homeobox), suggesting a intricate regulatory network underlying the complex process of bulbil initiation. This study offers a profound understanding of the bulbil initiation process and could potentially aid in refining molecular breeding techniques specific to P. ternata.

Harnessing Phytohormones: Advancing Plant Growth and Defence Strategies for Sustainable Agriculture

Phytohormones, pivotal regulators of plant growth and development, are increasingly recognized for their multifaceted roles in enhancing crop resilience against environmental stresses. In this review, we provide a comprehensive synthesis of current research on utilizing phytohormones to enhance crop productivity and fortify their defence mechanisms. Initially, we introduce the significance of phytohormones in orchestrating plant growth, followed by their potential utilization in bolstering crop defences against diverse environmental stressors. Our focus then shifts to an in-depth exploration of phytohormones and their pivotal roles in mediating plant defence responses against biotic stressors, particularly insect pests. Furthermore, we highlight the potential impact of phytohormones on agricultural production while underscoring the existing research gaps and limitations hindering their widespread implementation in agricultural practices. Despite the accumulating body of research in this field, the integration of phytohormones into agriculture remains limited. To address this discrepancy, we propose a comprehensive framework for investigating the intricate interplay between phytohormones and sustainable agriculture. This framework advocates for the adoption of novel technologies and methodologies to facilitate the effective deployment of phytohormones in agricultural settings and also emphasizes the need to address existing research limitations through rigorous field studies. By outlining a roadmap for advancing the utilization of phytohormones in agriculture, this review aims to catalyse transformative changes in agricultural practices, fostering sustainability and resilience in agricultural settings.

Synthesis of Extracellular L-lysine-α-oxidase along with Degrading Enzymes by Trichoderma cf. aureoviride Rifai VKM F-4268D: Role in Biocontrol and Systemic Plant Resistance

When cultivating on wheat bran or deactivated fungal mycelium as a model of "natural growth", the ability of Trichoderma to synthesize extracellular L-lysine-α-oxidase (LysO) simultaneously with cell-wall-degrading enzymes (proteases, xylanase, glucanases, chitinases, etc.), responsible for mycoparasitism, was shown. LysO, in turn, causes the formation of H2O2 and pipecolic acid. These compounds are known to be signaling molecules and play an important role in the induction and development of systemic acquired resistance in plants. Antagonistic effects of LysO have been demonstrated against phytopathogenic fungi and Gram-positive or Gram-negative bacteria with dose-dependent cell death. The antimicrobial effect of LysO decreased in the presence of catalase. The generating intracellular ROS in the presence of LysO was also shown in both bacteria and fungi, which led to a decrease in viable cells. These results suggest that the antimicrobial activity of LysO is due to two factors: the formation of exogenous hydrogen peroxide as a product of the enzymatic oxidative deamination of L-lysine and the direct interaction of LysO with the cell wall of the micro-organisms. Thus, LysO on its own enhances the potential of the producer in the environment; namely, the enzyme complements the strategy of the fungus in biocontrol and indirectly participates in inducing SAR and regulating the relationship between pathogens and plants.

Three new discovery effector proteins from Candidatus Liberibacter asiaticus psy62 inhibit plant defense through interaction with AtCAT3 and AtGAPA

KEY MESSAGE

We identify three SDEs that inhibiting host defence from Candidatus Liberibacter asiaticus psy62, which is an important supplement to the pathogenesis of HLB. Candidatus Liberibacter asiaticus (CLas) is the main pathogen of citrus Huanglongbing (HLB). 38 new possible sec-dependent effectors (SDEs) of CLas psy62 were predicted by updated predictor SignalP 5.0, which 12 new SDEs were found using alkaline phosphate assay. Among them, SDE4310, SDE4435 and SDE4955 inhibited hypersensitivity reactions (HR) in Arabidopsis thaliana (Arabidopsis, At) and Nicotiana benthamiana leaves induced by pathogens, which lead to a decrease in cell death and reactive oxygen species (ROS) accumulation. And the expression levels of SDE4310, SDE4435, and SDE4955 genes elevated significantly in mild symptom citrus leaves. When SDE4310, SDE4435 and SDE4955 were overexpressed in Arabidopsis, HR pathway key genes pathogenesis-related 2 (PR2), PR5, nonexpressor of pathogenesis-related 1 (NPR1) and isochorismate synthase 1 (ICS1) expression significantly decreased and the growth of pathogen was greatly increased relative to control with Pst DC3000/AvrRps4 treatment. Our findings also indicated that SDE4310, SDE4435 and SDE4955 interacted with AtCAT3 (catalase 3) and AtGAPA (glyceraldehyde-3-phosphate dehydrogenase A). In conclusion, our results suggest that SDE4310, SDE4435 and SDE4955 are CLas psy62 effector proteins that may have redundant functions. They inhibit ROS burst and cell death by interacting with AtCAT3 and AtGAPA to negatively regulate host defense.

Thaumatin-like Proteins in Legumes: Functions and Potential Applications-A Review

Thaumatin-like proteins (TLPs) comprise a complex and evolutionarily conserved protein family that participates in host defense and several developmental processes in plants, fungi, and animals. Importantly, TLPs are plant host defense proteins that belong to pathogenesis-related family 5 (PR-5), and growing evidence has demonstrated that they are involved in resistance to a variety of fungal diseases in many crop plants, particularly legumes. Nonetheless, the roles and underlying mechanisms of the TLP family in legumes remain unclear. The present review summarizes recent advances related to the classification, structure, and host resistance of legume TLPs to biotic and abiotic stresses; analyzes and predicts possible protein-protein interactions; and presents their roles in phytohormone response, root nodule formation, and symbiosis. The characteristics of TLPs provide them with broad prospects for plant breeding and other uses. Searching for legume TLP genetic resources and functional genes, and further research on their precise function mechanisms are necessary.

Mutagenesis-Derived Resistance to Black Point in Wheat

Black point, a severe global wheat disease, necessitates deploying resistant cultivars for effective control. However, susceptibility remains prevalent among most wheat cultivars. Identifying new sources of resistance and understanding their mechanisms are crucial for breeding resistant cultivars. This study pinpointed black point resistance in an ethyl methane sulfonate (EMS)-mutagenized wheat population of Wanyuanbai 1 (WYB) and analyzed resistant mutants using RNA-Seq. The findings revealed the following: (i) wyb-18, among 10,008 EMS-mutagenized lines, exhibited robust resistance with significantly lower black point incidence under artificial Bipolaris sorokiniana inoculation in 2020 and 2021 (average incidence of 5.2% over 2 years), markedly reduced compared with WYB (50.9%). (ii) wyb-18 kernels displayed black point symptoms at 12 days after inoculation (dai), 3 days later than WYB. At 15 dai, wyb-18 kernels had isolated black spots, unlike WYB kernels, where the entire embryo turned black. (iii) wyb-18 showed heightened antioxidant enzyme activity, including peroxidase, catalase, and superoxide dismutase. (iv) Analysis of 543 differentially expressed genes between wyb-18 and WYB at 9 dai identified enrichment in the MAPK signaling pathway through KEGG analysis. Ten genes in this pathway exhibited upregulated expression, while one was downregulated in wyb-18. Among these genes, PR1, WRKY11, SAPK5, and TraesCS1A02G326800 (chitin recognition protein) consistently showed upregulation in wyb-18, making them potential candidates for black point resistance. These results offer valuable germplasm resources for breeding and novel insights into the mechanisms of black point resistance.

Transcriptome analysis of genes involved in the pathogenesis mechanism of potato virus Y in potato cultivar YouJin

Introduction

Potatoes (Solanum tuberosum L.) can be infected by various viruses, but out of all of viruses, the potato virus Y (PVY) is the most detrimental. Research shows that the potato cultivar YouJin is especially vulnerable to PVY and displays severe symptoms, including leaf vein chlorosis, curled leaf margins, large necrotic spots on the leaf blades, and the growth of small new leaves.

Methods

PVY infection in potato cultivar YouJin was confirmed through symptom observation, RT-PCR, and Western blot analysis. Transcriptome sequencing was used to analyze the genes associated with PVY pathogenesis in this cultivar.

Result

Transcriptome analysis of differential genes was conducted in this study to examine the pathogenesis of PVY on YouJin. The results showed that 1,949 genes were differentially regulated, including 853 upregulated genes and 1,096 downregulated genes. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that carbohydrate synthesis and metabolism pathways were suppressed, and electron transferase and hydrolase activities were reduced. Moreover, there were increased expression levels of protein kinase genes. By focusing on plant-pathogen interaction pathways, six core genes all upregulating the WARK family of transcription factors were obtained. Additionally, a constructed PPI network revealed the identification of key modular differential genes, such as downregulated photosynthesis-related protein genes and upregulated AP2/ERF-ERF transcription factors. Functional network enrichment analysis revealed that PVY infection limited RNA metabolism, glutathionylation, and peroxiredoxin activity while triggering the expression of associated defense genes in YouJin. After analyzing the above, 26 DEGs were screened and 12 DEGs were confirmed via RT-qPCR.

Conclusion

These results establish a hypothetical framework for clarifying the pathogenesis of PVY in the YouJin variety of potatoes, which will help design the disease resistance of YouJin.

Recent Advances in Dissecting the Function of Ethylene in Interaction between Host and Pathogen

Pathogens influence the growth and development of plants, resulting in detrimental damage to their yields and quality. Ethylene, a gaseous phytohormone, serves a pivotal function in modulating diverse physiological processes in plants, including defense mechanisms against pathogen invasion. Ethylene biosynthesis is involved in both plants and pathogens. Recent empirical research elucidates the intricate interactions and regulatory mechanisms between ethylene and pathogens across various plant species. In this review, we provide a comprehensive overview of the latest findings concerning ethylene's role and its regulatory networks in host-pathogen interactions. Additionally, we explore the crosstalk between ethylene and other phytohormones. Points regarding ethylene emission and its modulation by pathogens are also emphasized. Moreover, we also discuss potential unresolved issues in the field that warrant further investigation.

Lipid mediated plant immunity in susceptible and tolerant soybean cultivars in response to Phytophthora sojae colonization and infection

BACKGROUND

Soybean is one of the most cultivated crops globally and a staple food for much of the world's population. The annual global crop losses due to infection by Phytophthora sojae is currently estimated at $20B USD, yet we have limited understanding of the role of lipid mediators in the adaptative strategies used by the host plant to limit infection. Since root is the initial site of this infection, we examined the infection process in soybean root infected with Phytophthora sojae using scanning electron microscopy to observe the changes in root morphology and a multi-modal lipidomics approach to investigate how soybean cultivars remodel their lipid mediators to successfully limit infection by Phytophthora sojae.

RESULTS

The results reveal the presence of elevated biogenic crystals and more severe damaged cells in the root morphology of the infected susceptible cultivar compared to the infected tolerant cultivars. Furthermore, induced accumulation of stigmasterol was observed in the susceptible cultivar whereas, induced accumulation of phospholipids and glycerolipids occurred in tolerant cultivar.

CONCLUSION

The altered lipidome reported in this study suggest diacylglycerol and phosphatidic acid mediated lipid signalling impacting phytosterol anabolism appears to be a strategy used by tolerant soybean cultivars to successfully limit infection and colonization by Phytophthora sojae.

Mining of disease-resistance genes in Crocus sativus based on transcriptome sequencing

Introduction: Crocus sativus L. has an important medicinal and economic value in traditional perennial Chinese medicine. However, due to its unique growth characteristics, during cultivation it is highly susceptible to disease. The absence of effective resistance genes restricts us to breed new resistant varieties of C. sativus. Methods: In present study, comprehensive transcriptome sequencing was introduced to explore the disease resistance of the candidate gene in healthy and corm rot-infected C. sativus. Results and discussion: Totally, 43.72 Gb of clean data was obtained from the assembly to generate 65,337 unigenes. By comparing the gene expression levels, 7,575 differentially expressed genes (DEGs) were primarily screened. A majority of the DEGs were completely in charge of defense and metabolism, and 152 of them were annotated as pathogen recognition genes (PRGs) based on the PGRdb dataset. The expression of some transcription factors including NAC, MYB, and WRKY members, changed significantly based on the dataset of transcriptome sequencing. Therefore, this study provides us some valuable information for exploring candidate genes involved in the disease resistance in C. sativus.

Unveiling the significance of rhizosphere: Implications for plant growth, stress response, and sustainable agriculture

In the rhizosphere, the activities within all processes and functions are primarily influenced by plant roots, microorganisms present in the rhizosphere, and the interactions between roots and microorganisms. The rhizosphere, a dynamic zone surrounding the roots, provides an ideal environment for a diverse microbial community, which significantly shapes plant growth and development. Microbial activity in the rhizosphere can promote plant growth by increasing nutrient availability, influencing plant hormonal signaling, and repelling or outcompeting pathogenic microbial strains. Understanding the associations between plant roots and soil microorganisms has the potential to revolutionize crop yields, improve productivity, minimize reliance on chemical fertilizers, and promote sustainable plant growth technologies. The rhizosphere microbiome could play a vital role in the next green revolution and contribute to sustainable and eco-friendly agriculture. However, there are still knowledge gaps concerning plant root-environment interactions, particularly regarding roots and microorganisms. Advances in metabolomics have helped to understand the chemical communication between plants and soil biota, yet challenges persist. This article provides an overview of the latest advancements in comprehending the communication and interplay between plant roots and microbes, which have been shown to impact crucial factors such as plant growth, gene expression, nutrient absorption, pest and disease resistance, and the alleviation of abiotic stress. By improving these aspects, sustainable agriculture practices can be implemented to increase the overall productivity of plant ecosystems.

Early Detection of Botrytis cinerea Infection in Cut Roses Using Thermal Imaging

Botrytis cinerea (B. cinerea) causes gray mold disease (GMD), which results in physiological disorders in plants that decrease the longevity and economic value of horticultural crops. To prevent the spread of GMD during distribution, a rapid, early detection technique is necessary. Thermal imaging has been used for GMD detection in various plants, including potted roses; however, its application to cut roses, which have a high global demand, has not been established. In this study, we investigated the utility of thermal imaging for the early detection of B. cinerea infection in cut roses by monitoring changes in petal temperature after fungal inoculation. We examined the effects of GMD on the postharvest quality and petal temperature of cut roses treated with different concentrations of fungal conidial suspensions and chemicals. B. cinerea infection decreased the flower opening, disrupted the water balance, and decreased the vase life of cut roses. Additionally, the average temperature of rose petals was higher for infected flowers than for non-inoculated flowers. One day before the appearance of necrotic symptoms (day 1 of the vase period), the petal temperature in infected flowers was significantly higher, by 1.1 °C, than that of non-inoculated flowers. The GMD-induced increase in petal temperature was associated with the mRNA levels of genes related to ethylene, reactive oxygen species, and water transport. Furthermore, the increase in temperature caused by GMD was strongly correlated with symptom severity and fungal biomass. A multiple regression analysis revealed that the disease incidence in the petals was positively related to the petal temperature one day before the appearance of necrotic symptoms. These results show that thermography is an effective technique for evaluating changes in petal temperature and a possible method for early GMD detection in the cut flower industry.

Comparative RNA-seq analysis of resistant and susceptible banana genotypes reveals molecular mechanisms in response to banana bunchy top virus (BBTV) infection

Bananas hold significant economic importance as an agricultural commodity, serving as a primary livelihood source, a favorite fruit, and a staple crop in various regions across the world. However, Banana bunchy top disease (BBTD), which is caused by banana bunchy top virus (BBTV), poses a considerable threat to banana cultivation. To understand the resistance mechanism and the interplay of host suitability factors in the presence of BBTV, we conducted RNA-seq-based comparative transcriptomics analysis on mock-inoculated and BBTV-inoculated samples from resistant (wild Musa balbisiana) and susceptible (Musa acuminata 'Lakatan') genotypes. We observed common patterns of expression for 62 differentially expressed genes (DEGs) in both genotypes, which represent the typical defense response of bananas to BBTV. Furthermore, we identified 99 DEGs exclusive to the 'Lakatan' banana cultivar, offering insights into the host factors and susceptibility mechanisms that facilitate successful BBTV infection. In parallel, we identified 151 DEGs unique to the wild M. balbisiana, shedding light on the multifaceted mechanisms of BBTV resistance, involving processes such as secondary metabolite biosynthesis, cell wall modification, and pathogen perception. Notably, our validation efforts via RT-qPCR confirmed the up-regulation of the glucuronoxylan 4-O-methyltransferase gene (14.28 fold-change increase), implicated in xylan modification and degradation. Furthermore, our experiments highlighted the potential recruitment of host's substrate adaptor ADO (30.31 fold-change increase) by BBTV, which may play a role in enhancing banana susceptibility to the viral pathogen. The DEGs identified in this work can be used as basis in designing associated gene markers for the precise integration of resistance genes in marker-assisted breeding programs. Furthermore, the findings can be applied to develop genome-edited banana cultivars targeting the resistance and susceptibility genes, thus developing novel cultivars that are resilient to important diseases.

PCLLA-nanoHA Bone Substitute Promotes M2 Macrophage Polarization and Improves Alveolar Bone Repair in Diabetic Environments

The utilization of bioresorbable synthetic bone substitutes with immunomodulatory properties has gained significant attention in dental clinical applications for the absorption of alveolar bone induced by orthodontic treatment. In this study, we developed two distinct materials: a conventional hydroxyapatite (HA) bone powder comprised of hydroxyapatite particles and nanoHA embedded within a poly(caprolactone-co-lactide) (PCLLA) elastomeric matrix. We assessed the physicochemical characteristics of the bone substitute, specifically focusing on its composition and the controlled release of ions. Our findings show that PCLLA-nanoHA has deformable properties under 40 N, and a significant release of Ca and P elements was noted after 7 days in aqueous settings. Moreover, at the protein and gene expression levels, PCLLA-nanoHA enhances the capacity of macrophages to polarize towards an M2 phenotype in vitro. In vivo, PCLLA-nanoHA exhibits comparable effects to standard HA bone powder in terms of promoting alveolar bone regeneration. Extensive investigations reveal that PCLLA-nanoHA surpasses the commonly employed HA bone powder in stimulating bone tissue repair in diabetic mice. We have identified that PCLLA-nanoHA regulates macrophage M2 polarization by activating the PI3K/AKT and peroxisome proliferator-activated receptor gamma (PPAR) signaling pathways, thereby facilitating a favorable local immune microenvironment conducive to bone repair and regeneration. Our findings suggest that PCLLA-nanoHA presents itself as a promising bioresorbable bone substitute with properties that promote macrophage M2 polarization, particularly in the context of regulating the local microenvironment of alveolar bone in diabetic mice, potentially facilitating bone tissue regeneration.

Transcriptome and metabolome analyses revealed the response mechanism of pepper roots to Phytophthora capsici infection

BACKGROUND

Phytophthora root rot caused by the oomycete Phytophthora capsici is the most devastating disease in pepper production worldwide, and current management strategies have not been effective in preventing this disease. Therefore, the use of resistant varieties was regarded as an important part of disease management of P. capsici. However, our knowledge of the molecular mechanisms underlying the defense response of pepper roots to P. capsici infection is limited.

METHODS

A comprehensive transcriptome and metabolome approaches were used to dissect the molecular response of pepper to P. capsici infection in the resistant genotype A204 and the susceptible genotype A198 at 0, 24 and 48 hours post-inoculation (hpi).

RESULTS

More genes and metabolites were induced at 24 hpi in A204 than A198, suggesting the prompt activation of defense responses in the resistant genotype, which can attribute two proteases, subtilisin-like protease and xylem cysteine proteinase 1, involved in pathogen recognition and signal transduction in A204. Further analysis indicated that the resistant genotype responded to P. capsici with fine regulation by the Ca2+- and salicylic acid-mediated signaling pathways, and then activation of downstream defense responses, including cell wall reinforcement and defense-related genes expression and metabolites accumulation. Among them, differentially expressed genes and differentially accumulated metabolites involved in the flavonoid biosynthesis pathways were uniquely activated in the resistant genotype A204 at 24 hpi, indicating a significant role of the flavonoid biosynthesis pathways in pepper resistance to P. capsici.

CONCLUSION

The candidate transcripts may provide genetic resources that may be useful in the improvement of Phytophthora root rot-resistant characters of pepper. In addition, the model proposed in this study provides new insight into the defense response against P. capsici in pepper, and enhance our current understanding of the interaction of pepper-P. capsici.

Mining of Minor Disease Resistance Genes in V. vinifera Grapes Based on Transcriptome

Intraspecific recurrent selection in V. vinifera is an effective method for grape breeding with high quality and disease resistance. The core theory of this method is the substitution accumulation of multi-genes with low disease resistance. The discovery of multi-genes for disease resistance in V. vinifera may provide a molecular basis for breeding for disease resistance in V. vinifera. In this study, resistance to downy mildew was identified, and genetic analysis was carried out in the intraspecific crossing population of V. vinifera (Ecolly × Dunkelfelder) to screen immune, highly resistant and disease-resistant plant samples; transcriptome sequencing and differential expression analysis were performed using high-throughput sequencing. The results showed that there were 546 differential genes (194 up-regulated and 352 down-regulated) in the immune group compared to the highly resistant group, and 199 differential genes (50 up-regulated and 149 down-regulated) in the highly resistant group compared to the resistant group, there were 103 differential genes (54 up-regulated and 49 down-regulated) in the immune group compared to the resistant group. KEGG analysis of differentially expressed genes in the immune versus high-resistance group. The pathway is mainly concentrated in phenylpropanoid biosynthesis, starch and sucrose metabolism, MAPK signaling pathway-plant, carotenoid biosyn-thesis and isoquinoline alkaloid biosynthesis. The differential gene functions of immune and resistant, high-resistant and resistant combinations were mainly enriched in plant-pathogen interaction pathway. Through the analysis of disease resistance-related genes in each pathway, the potential minor resistance genes in V. vinifera were mined, and the accumulation of minor resistance genes was analyzed from the molecular level.

Unveiling the Secrets of Calcium-Dependent Proteins in Plant Growth-Promoting Rhizobacteria: An Abundance of Discoveries Awaits

The role of Calcium ions (Ca2+) is extensively documented and comprehensively understood in eukaryotic organisms. Nevertheless, emerging insights, primarily derived from studies on human pathogenic bacteria, suggest that this ion also plays a pivotal role in prokaryotes. In this review, our primary focus will be on unraveling the intricate Ca2+ toolkit within prokaryotic organisms, with particular emphasis on its implications for plant growth-promoting rhizobacteria (PGPR). We undertook an in silico exploration to pinpoint and identify some of the proteins described in the existing literature, including prokaryotic Ca2+ channels, pumps, and exchangers that are responsible for regulating intracellular Calcium concentration ([Ca2+]i), along with the Calcium-binding proteins (CaBPs) that play a pivotal role in sensing and transducing this essential cation. These investigations were conducted in four distinct PGPR strains: Pseudomonas chlororaphis subsp. aurantiaca SMMP3, P. donghuensis SVBP6, Pseudomonas sp. BP01, and Methylobacterium sp. 2A, which have been isolated and characterized within our research laboratories. We also present preliminary experimental data to evaluate the influence of exogenous Ca2+ concentrations ([Ca2+]ex) on the growth dynamics of these strains.

Entomopathogenic Fungus-Related Priming Defense Mechanisms in Cucurbits Impact Spodoptera littoralis (Boisduval) Fitness

Entomopathogenic fungi (EPF) exhibit direct and indirect mechanisms to increase plant resistance against biotic and abiotic stresses. Plant responses to these stresses are interconnected by common regulators such as ethylene (ET), which is involved in both iron (Fe) deficiency and induced systemic resistance responses. In this work, the roots of cucurbit seedlings were primed with Metarhizium brunneum (EAMa 01/58-Su strain), and relative expression levels of 18 genes related to ethylene (ET), jasmonic acid (JA), and salicylic acid (SA) synthesis, as well as pathogen-related (PR) protein genes, were studied by reverse transcription-quantitative PCR (qRT-PCR). Effects of priming on Spodoptera littoralis were studied by feeding larvae for 15 days with primed and control plants. Genes showed upregulation in studied species; however, the highest relative expression was observed in roots and shoots of plants with Fe deficiency, demonstrating the complexity and the overlapping degree of the regulatory network. EIN2 and EIN3 should be highlighted; both are key genes of the ET transduction pathway that enhanced their expression levels up to eight and four times, respectively, in shoots of primed cucumber. Also, JA and SA synthesis and PR genes showed significant upregulation during the observation period (e.g., the JA gene LOX1 increased 506 times). Survival and fitness of S. littoralis were affected with significant effects on mortality of larvae fed on primed plants versus controls, length of the larval stage, pupal weight, and the percentage of abnormal pupae. These results highlight the role of the EAMa 01/58-Su strain in the induction of resistance, which could be translated into direct benefits for plant development. IMPORTANCE Entomopathogenic fungi are multipurpose microorganisms with direct and indirect effects on insect pests. Also, EPF provide multiple benefits to plants by solubilizing minerals and facilitating nutrient acquisition. A very interesting and novel effect of these fungi is the enhancement of plant defense systems by inducing systematic and acquired resistance. However, little is known about this function. This study sheds light on the molecular mechanisms involved in cucurbits plants' defense activation after being primed by the EPF M. brunneum. Furthermore, the subsequent effects on the fitness of the lepidopteran pest S. littoralis are shown. In this regard, a significant upregulation was recorded for the genes that regulate JA, SA, and ET pathways. This increased expression of defense genes caused lethal and sublethal effects on S. littoralis. This could be considered an added value for the implementation of EPF in integrated pest management programs.

Early and Late Transcriptomic and Metabolomic Responses of Rhododendron 'Xiaotaohong' Petals to Infection with Alternaria sp

In recent years, petal blight disease caused by pathogens has become increasingly epidemic in Rhododendron. Breeding disease-resistant rhododendron is considered to be a more environmentally friendly strategy than is the use of chemical reagents. In this study, we aimed to investigate the response mechanisms of rhododendron varieties to petal blight, using transcriptomics and metabolomics analyses. Specifically, we monitored changes in gene expression and metabolite accumulation in Rhododendron 'Xiaotaohong' petals infected with the Alternaria sp. strain (MR-9). The infection of MR-9 led to the development of petal blight and induced significant changes in gene transcription. Differentially expressed genes (DEGs) were predominantly enriched in the plant-pathogen interaction pathway. These DEGs were involved in carrying out stress responses, with genes associated with H2O2 production being up-regulated during the early and late stages of infection. Correspondingly, H2O2 accumulation was detected in the vicinity of the blight lesions. In addition, defense-related genes, including PR and FRK, exhibited significant up-regulated expression during the infection by MR-9. In the late stage of the infection, we also observed significant changes in differentially abundant metabolites (DAMs), including flavonoids, alkaloids, phenols, and terpenes. Notably, the levels of euscaphic acid, ganoderol A, (-)-cinchonidine, and theophylline in infected petals were 21.8, 8.5, 4.5, and 4.3 times higher, respectively, compared to the control. Our results suggest that H2O2, defense-related genes, and DAM accumulation are involved in the complex response mechanisms of Rhododendron 'Xiaotaohong' petals to MR-9 infection. These insights provide a deeper understanding of the pathogenesis of petal blight disease and may have practical implications for developing disease-resistant rhododendron varieties.

Transcriptomic Analysis and Salt-Tolerance Gene Mining during Rice Germination

Salt stress is an important environmental factor affecting crop growth and development. One of the important ways to improve the salt tolerance of rice is to identify new salt-tolerance genes, reveal possible mechanisms, and apply them to the creation of new germplasm and the breeding of new varieties. In this study, the salt-sensitive japonica variety Tong 35 (T35) and salt-tolerant japonica variety Ji Nongda 709 (JND709) were used. Salt stress treatment with a 150 mmol/L NaCl solution (the control group was tested without salt stress treatment simultaneously) was continued until the test material was collected after the rice germination period. Twelve cDNA libraries were constructed, and 5 comparator groups were established for transcriptome sequencing. On average, 9.57G of raw sequencing data were generated per sample, with alignment to the reference genome above 96.88% and alignment to guanine-cytosine (GC) content above 53.86%. A total of 16,829 differentially expressed genes were present in the five comparison groups, of which 2390 genes were specifically expressed in T35 (category 1), 3306 genes were specifically expressed in JND709 (category 2), and 1708 genes were differentially expressed in both breeds (category 3). Differentially expressed genes were subjected to gene ontology (GO), functional enrichment analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, which revealed that these genes belonged to three main classes: molecular function, cellular components, and biological processes. KEGG pathway analysis showed that the significantly enriched pathways for these differentially expressed genes included phenylpropane biosynthesis, phytohormone signaling, and the interaction of plants with pathogens. In this study, we provided a reference for studying the molecular mechanism underlying salt tolerance during germination.

Molecular Mechanisms Underlying Potential Pathogen Resistance in Cannabis sativa

Cannabis (Cannabis sativa L.) is one of the earliest cultivated crops, valued for producing a broad spectrum of compounds used in medicinal products and being a source of food and fibre. Despite the availability of its genome sequences, few studies explore the molecular mechanisms involved in pathogen defense, and the underlying biological pathways are poorly defined in places. Here, we provide an overview of Cannabis defence responses against common pathogens, such as Golovinomyces spp., Fusarium spp., Botrytis cinerea and Pythium spp. For each of these pathogens, after a summary of their characteristics and symptoms, we explore studies identifying genes involved in Cannabis resistance mechanisms. Many studies focus on the potential involvement of disease-resistance genes, while others refer to other plants however whose results may be of use for Cannabis research. Omics investigations allowing the identification of candidate defence genes are highlighted, and genome editing approaches to generate resistant Cannabis species based on CRISPR/Cas9 technology are discussed. According to the emerging results, a potential defence model including both immune and defence mechanisms in Cannabis plant-pathogen interactions is finally proposed. To our knowledge, this is the first review of the molecular mechanisms underlying pathogen resistance in Cannabis.

Fructan exohydrolases (FEHs) are upregulated by salicylic acid together with defense-related genes in non-fructan accumulating plants

The identification of several fructan exohydrolases (FEHs, EC 3.2.1.80) in non-fructan accumulating plants raised the question of their roles. FEHs may be defense-related proteins involved in the interactions with fructan-accumulating microorganisms. Since known defense-related proteins are upregulated by defense-related phytohormones, we tested the hypothesis that FEHs of non-fructan accumulating plants are upregulated by salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) using the model plant Arabidopsis thaliana and the agronomically relevant and genetically related species Brassica napus. By sequence homologies with the two known FEH genes of A. thaliana, At6-FEH, and At6&1-FEH, the genes coding for the putative B. napus FEHs, Bn6-FEH and Bn6&1-FEH, were identified. Plants were treated at root level with SA, methyl jasmonate (MeJA) or 1-aminocyclopropane-1-carboxylic acid (ACC). The transcript levels of defense-related and FEH genes were measured after treatments. MeJA and ACC did not upregulate FEHs, while HEL (HEVEIN-LIKE PREPROTEIN) expression was enhanced by both phytohormones. In both species, the expression of AOS, encoding a JA biosynthesis enzyme, was enhanced by MeJA and that of the defensine PDF1.2 and the ET signaling transcription factor ERF1/2 by ACC. In contrast, SA not only increased the expression of genes encoding antimicrobial proteins (PR1 and HEL) and the defense-related transcription factor WRKY70 but also that of FEH genes, in particular 6&1-FEH genes. This result supports the putative role of FEHs as defense-related proteins. Genotypic variability of SA-mediated FEH regulation (transcript level and activities) was observed among five varieties of B. napus, suggesting different susceptibilities toward fructan-accumulating pathogens.

Coffee-Associated Endophytes: Plant Growth Promotion and Crop Protection

Endophytic microbes are a ubiquitous group of plant-associated communities that colonize the intercellular or intracellular host tissues while providing numerous beneficial effects to the plants. All the plant species are thought to be associated with endophytes, majorly constituted with bacteria and fungi. During the last two decades, there has been a considerable movement toward the study of endophytes associated with coffee plants. In this review, the main consideration is given to address the coffee-associated endophytic bacteria and fungi, particularly their action on plant growth promotion and the biocontrol of pests. In addition, we sought to identify and analyze the gaps in the available research. Additionally, the potential of endophytes to improve the quality of coffee seeds is briefly discussed. Even though there are limited studies on the subject, the potentiality of coffee endophytes in plant growth promotion through enhancing nitrogen fixation, availability of minerals, nutrient absorption, secretion of phytohormones, and other bioactive metabolites has been well recognized. Further, the antagonistic effect against various coffee pathogenic bacteria, fungi, nematodes, and also insect pests leads to the protection of the crop. Furthermore, it is recognized that endophytes enhance the sensory characteristics of coffee as a new field of study.

Allelochemical Interactions in the Trophic System «Henosepilachna vigintioctomaculata Motschulsky-Solanum tuberosum Linneus»

Henosepilachna vigintioctomaculata is an intrinsic element in the agroecosystem of potato fields. The issues of relationships in the system "potato ladybird beetle-potato plant" have not yet been studied. To study the effect of potato varieties on the potato ladybird beetle, only hatched and active larvae with a hatching rate close to 100% were selected from a laboratory colony. Larvae of the first summer generation collected in potato fields were used in our study to determine the level of adrenaline in the bodies of insects, fresh potato leaves were used to study the content of glycoalkaloids, the content and activity of proteinase inhibitors. The larvae that fed on plants of varieties Belmonda, Queen Anne, Lilly, Dachny, Kazachok, Yubilyar, and Avgustin demonstrated the highest level of stress while the stress level in those that fed on variety Smak was the lowest. The damage inflicted by potato ladybird beetles on leaves of some studied potato varieties led to a progressive increase in the content of glycoalkaloids already within 24 h after the phytophages had been transferred. In most cases, the content of glycoalkoloids increased by 20% within five days. Potato ladybird beetles feeding on plants of different potato varieties caused a progressive increase in proteinase inhibitors (% of the control). Plants of variety Smak did not show a significant increase in the content of alkaloids in the herbage in response to the damage. A correlation was established between the mortality rate, the activity of proteinase inhibitors, the dynamics of glycoalkaloids, and the level of adrenaline, which could be formulated as follows: the higher the content of glycoalkaloids and the activity of proteinase inhibitors in the tissues of potato plants, the higher the level of stress in the potato ladybird beetles that feed on them.

Transcriptomic analysis reveals that Bacillomycin D-C16 induces multiple pathways of disease resistance in cherry tomato

BACKGROUND

Bacillomycin D-C16 can induce resistance in cherry tomato against pathogens; however, the underlying molecular mechanism is poorly understood. Here, the effect of Bacillomycin D-C16 on induction of disease resistance in cherry tomato was investigated using a transcriptomic analysis.

RESULTS

Transcriptomic analysis revealed a series of obvious enrichment pathways. Bacillomycin D-C16 induced phenylpropanoid biosynthesis pathways and activated the synthesis of defense-related metabolites including phenolic acids and lignin. Moreover, Bacillomycin D-C16 triggered a defense response through both hormone signal transduction and plant-pathogen interactions pathways, and increased the transcription of several transcription factors (e.g., AP2/ERF, WRKY and MYB). These transcription factors might contribute to the further activated the expression of defense-related genes (PR1, PR10 and CHI) and stimulated the accumulation of H2O2.

CONCLUSION

Bacillomycin D-C16 can induce resistance in cherry tomato by activating the phenylpropanoid biosynthesis pathway, hormone signal transduction pathway and plant-pathogen interactions pathway, thus activating comprehensive defense reaction against pathogen invasion. These results provided a new insight into the bio-preservation of cherry tomato by the Bacillomycin D-C16.

Oxylipins and Reactive Carbonyls as Regulators of the Plant Redox and Reactive Oxygen Species Network under Stress

Reactive oxygen species (ROS), and in particular H2O2, serve as essential second messengers at low concentrations. However, excessive ROS accumulation leads to severe and irreversible cell damage. Hence, control of ROS levels is needed, especially under non-optimal growth conditions caused by abiotic or biotic stresses, which at least initially stimulate ROS synthesis. A complex network of thiol-sensitive proteins is instrumental in realizing tight ROS control; this is called the redox regulatory network. It consists of sensors, input elements, transmitters, and targets. Recent evidence revealed that the interplay of the redox network and oxylipins–molecules derived from oxygenation of polyunsaturated fatty acids, especially under high ROS levels–plays a decisive role in coupling ROS generation and subsequent stress defense signaling pathways in plants. This review aims to provide a broad overview of the current knowledge on the interaction of distinct oxylipins generated enzymatically (12-OPDA, 4-HNE, phytoprostanes) or non-enzymatically (MDA, acrolein) and components of the redox network. Further, recent findings on the contribution of oxylipins to environmental acclimatization will be discussed using flooding, herbivory, and establishment of thermotolerance as prime examples of relevant biotic and abiotic stresses.