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BACKGROUND: Plant fungal diseases pose a significant threat to crop production. The extensive use of chemical pesticides has led to growing environmental safety risks and pesticide resistance of various plant pathogens. Therefore, it is an urgent task to explore novel eco‐friendly fungicidal agents with high efficacy to combat fungal infection. RESULTS: In this study, we rationally designed a series of novel thymol derivatives by incorporation of the sulfonamide moiety and evaluated their biological activities against plant pathogenic fungi. The bioassay results underscored the remarkable in vitro antifungal activity of compounds 5m and 5t against Phytophthora capsici (P. capsici), with EC50 values of 8.420 and 8.414 μg/mL, respectively. Their efficacies were superior to that of widely used commercial fungicides azoxystrobin (AZO, 20.649 μg/mL) and cabendazim (CAB, 251.625 μg/mL). Furthermore, compound 5v exhibited excellent in vitro antifungal activity against Sclerotinia sclerotiorum (S. sclerotiorum), with an EC50 value of 12.829 μg/mL, significantly outperforming AZO (63.629 μg/mL). In vivo bioassays demonstrated the impactful activity of compound 5v against S. sclerotiorum, achieving over 98% curative and protective efficacies at the concentration of 200 μg/mL. Further mechanistic investigations unveiled that compound 5v induced mycelial shrinkage and collapse in S. sclerotiorum, resulting in organelle damage and the accumulation of antioxidant enzyme activity. CONCLUSION: The significant antifungal efficacy of the prepared thymol derivatives shall encourage further exploration of compound 5v as a promising candidate to develop novel fungicides for crop protection. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

One obstacle to pepper production is the high intensity of plant disease attacks. One of these is stem rot disease caused by the fungus Phytophthora capsici. Therefore, appropriate technology is needed to control disease and simultaneously increase plant growth by using rhizobacteria that are environmentally friendly and can produce growth hormones, dissolve phosphate, and fix nitrogen. This study aimed to obtain rhizobacterial isolates that can control the pathogen P. capsici, which causes root rot disease, while also increasing plant growth. This study was conducted at the Agronomy Laboratory of the Plant Cultivation Study Program, Samarinda State Agricultural Polytechnic. The study used a completely randomized design consisting of four treatments with four replicates to obtain 16 experimental units. The variables observed included the latent period, disease incidence and severity, increase in plant height, number of leaves, and stem diameter. The resulting data were analyzed using analysis of variance (ANOVA). The results of the analysis showing a real effect were followed by the Least Significant Difference test (BNT)a=0.05. The results of this study showed that the application of a combination of rhizobacteria was able to overcome stem rot disease and simultaneously increase the growth of pepper plant seedlings. The combination of rhizobacteria isolate P01 + TA2 treatment can reduce the latent period of disease to 12.00 days compared to 5.50 days without rhizobacteria, the disease incidence rate was 6.25% with a severity level of 2.50%, lower than of treatment (control) at 37.50 % (disease incidence) and 47.50% (disease severity). In addition, the combination of rhizobacterial isolates P01 + TA2 was able to increase the growth of pepper plant seeds, as shown by the increase in plant height, number of leaves, and stem diameter. [ABSTRACT FROM AUTHOR]

Phytophthora capsici and P. tropicalis are the two species of Phytophthora associated with foot rot disease of black pepper in India. High genetic diversity amongst the Phytophthora species contributes to its wide host range and variability in the virulence pattern. In the present study, genetic diversity of Phytophthora species infecting black pepper was analysed using RAMS (Random Amplified Microsatellites) and REP (Repetitive Extragenic Palindromic)-PCR fingerprinting. Forty-eight isolates, 24 each of P. capsici and P. tropicalis collected from major black pepper growing states, such as Karnataka, Kerala, Tamil Nadu and Goa, were used in the study. The analyses revealed a total of 160 loci of which 150 (93.75%) were polymorphic. UPGMA cluster and PCoA analysis based on combined RAMS and REP-PCR data clearly grouped the P. capsici and P. tropicalis isolates into two clusters which were further divided into four sub-clusters viz., I & II (P. capsici) and III & IV (P. tropicalis). The study clearly indicated that all the isolates were genetically unique and the entire population was heterogeneous. REP-PCR primers showed more polymorphic loci than RAMS primers. Further, sixteen isolates were selected for morphological and infectivity analyses under in vitro conditions. The isolates exhibited varied colony morphology, sporangial shapes and belonged to A1 mating type. Under in vitro conditions, all the sixteen black pepper Phytophthora isolates could infect nutmeg, tomato, chilli, pumpkin, and cucumber and few of the isolates could infect cardamom. None of the isolates could infect coconut, areca nut and vanilla. [ABSTRACT FROM AUTHOR]

In this paper, a series of derivatives were synthesized by introducing the pharmacophore pyrazole ring and piperazine ring into the structure of the natural product myricetin through an amide bond. The structures were determined using carbon spectrum and hydrogen spectrum high-resolution mass spectrometry. Biological activities of those compounds against bacteria, including Xac (Xanthomonas axonopodis pv. Citri), Psa (Pseudomonas syringae pv. Actinidiae) and Xoo (Xanthomonas oryzae pv. Oryzae) were tested. Notably, D6 exhibited significant bioactivity against Xoo with an EC50 value of 18.8 μg/mL, which was higher than the control drugs thiadiazole-copper (EC50 = 52.9 μg/mL) and bismerthiazol (EC50 = 69.1 μg/mL). Furthermore, the target compounds were assessed for their antifungal activity against ten plant pathogenic fungi. Among them, D1 displayed excellent inhibitory activity against Phomopsis sp. with an EC50 value of 16.9 μg/mL, outperforming the control agents azoxystrobin (EC50 = 50.7 μg/mL) and fluopyram (EC50 = 71.8 μg/mL). In vitro tests demonstrated that D1 possessed curative (60.6%) and protective (74.9%) effects on postharvest kiwifruit. To investigate the active mechanism of D1, its impact on SDH activity was evaluated based on its structural features and further confirmed through molecular docking. Subsequently, the malondialdehyde content of D1-treated fungi was measured, revealing that D1 could increase malondialdehyde levels, thereby causing damage to the cell membrane. Additionally, the EC50 value of D16 on P. capsici was 11.3 μg/mL, which was superior to the control drug azoxystrobin (EC50 = 35.1 μg/mL), and the scanning electron microscopy results indicated that the surface of drug-treated mycelium was ruffled, and growth was significantly affected. [ABSTRACT FROM AUTHOR]

Despite extensive works on miRNA's role during plant–oomycete interaction, its role in Capsicum annuum–Phytophthora capsici pathosystem is not fully explored. Therefore, the present study was designed to identify known and novel miRNAs along with their target genes in two contrasting chili peppers genotypes, i.e., GojamMecha_9086 (resistant) and Dabat_80045 (susceptible) under P. capsici infection associated with modulating the defense response during disease pathogenesis. The result demonstrated 79 known miRNAs corresponding to 24 miRNAs families and 477 novel miRNAs along with 22,895 potential targets, including 30 defense-related target genes against P. capsici infection. The expression analysis of 29 known and 157 novel miRNAs in resistant and 30 known and 177 novel miRNAs in susceptible genotypes revealed differential accumulation patterns. qRT-PCR analysis of 8 defense-related miRNAs representing 4 novels (Pz-novel-miR428-1, Pz-novel-miR160-1, Pz-novel-miR1028-1, Pz-novel-miR204-1) and 4 known miRNAs (Pz-known-miR803-1, Pz-known-miR2059-1, Pz-known-miR2560-1, Pz-known-miR1872-1) revealed differential accumulation pattern in both resistant and susceptible genotypes. Additionally, validation of eight target genes of miRNAs using regional amplification quantitative RT-PCR (RA-PCR), a superior technique to 5′-RNA Ligase-Mediated-rapid amplification of cDNA ends (5′ RLM-RACE), revealed expression of six target genes positively correlated with their corresponding miRNAs in RC versus RI leaf, while five target genes observed an inverse correlation with their corresponding miRNAs in SC versus SI leaf, suggesting their key role during disease response. The Pz-known-miR1872-PODs pair showed perfect inverse relation in all four samples. The significant findings of the current study provide comprehensive genome-wide information about the repertoire of miRNAs and their target genes expressed in resistant and susceptible chili pepper genotypes, which can serve as a valuable resource for better understanding the post-transcriptional regulatory mechanism during C. annuum–P. capsici pathosystem. [ABSTRACT FROM AUTHOR]

The efforts to signify the relevance of tRNA modifications were always within the limits of prokaryotes, humans, and some fewer model plant systems. The story of tRNA modifications in higher plants is still overlooked, especially in non-model spice crops. Stress causes alterations in tRNA modifications to facilitate the downstream functions of tRNAs. The present study was done to identify and better understand the fate of tRNA nucleoside modifications during biotic stress response in a widely used spice crop called Black pepper. We have uncovered the various tRNA nucleoside modifications present in black pepper. Methylations were the predominant nucleoside modifications in black pepper tRNAs.Furthermore, the different methyltransferase gene candidates implicated in catalyzing tRNA nucleoside methylations in black pepper were also identified. The LC-MS profile showed that certain tRNA nucleoside modifications showed varied abundance upon P. capsici infection. The N4-acetylcytidine (ac4C) nucleoside modification has shown a constant hike at 24 and 48 hpi. At the same time, some nucleoside modifications have exhibited a time-dependent abundance. Altogether our study suggests that tRNA modifications and the expression of associated enzymes are altered during biotic stress regulation.

Foot rot caused by Phytophthora is one of the major diseases of black pepper (Piper nigrum L.). Accurate and timely diagnosis of the disease is crucial for its successful management. Although PCR and qPCR assays are used for detection, the cost and time required to perform these assays are high. Recombinase polymerase amplification (RPA) assay has the advantage of minimal assay time and it is performed under isothermal conditions. Hence, RPA assay was developed for the detection of P. capsici and P. tropicalis and compared with newly developed end-point PCR test. Out of three sets of primers analyzed, a primer set based on the Ypt1 gene successfully amplified a 230/231 bp product. Optimum amplification of RPA products were observed when the assay was performed at 37 °C with 14 mM magnesium acetate for 40 min. Sensitivity analysis using serial dilutions indicated that RPA is 10 times more sensitive than end-point PCR. During specificity analysis, non-specific bands were observed with other Phytophthora species, and hence the assay was further refined with betaine wherein addition of 1.0 M betaine avoided amplification of non-specific bands. The optimized RPA assay could detect Phytophthora from infected black pepper leaf, stem and root using both purified DNA and crude extracts. The end-point PCR test successfully differentiated the two species of Phytophthora in a validation test. These results indicate the robustness of the developed end-point PCR and RPA assays and its potential application in detection and differentiation of P. capsici and P. tropicalis infecting black pepper. [ABSTRACT FROM AUTHOR]

Phytophthora capsici is one of the major pathogens found in pepper production, especially in bell pepper. Due to the high level of genetic diversity of the pathogen, bell pepper varieties with broad genetic resistance are essential for disease management. Criollo de Morelos - 334 (CM334), a landrace that has a high level of genetic resistance to P. capsici, has been used as the resistant source for P. capsici to generate a recombinant inbred line (RIL) population with the susceptible bell pepper cultivar Maor. From the resulting population, quantitative trait locus (QTL) models explaining resistance to each of four isolates of P. capsici were derived from QTL regions on three chromosomes using stepwiseqtl in R/qtl. A single region of chromosome 5 contained major QTL for resistance to each of the four isolates. Two isolate-specific QTL conferring resistance to isolates PWB53 and PWB106 were located on chromosomes 10 and 11, respectively. Both isolate-specific QTL had epistatic interactions with a major QTL on chromosome 5. Using the pepper reference genome and gene annotation, candidate genes for P. capsici resistance within 1.5-logarithm of odds (LOD) interval were identified. Based on functional annotations derived from Arabidopsis thaliana and solanaceous crop databases, multiple candidate genes related to resistance (R) gene complexes or to plant immune system were found under the QTL on all three chromosomes. A comparison of the locations of resistance QTL and previously identified horticultural QTL using the same population revealed tight linkage between resistance to P. capsici and a stem pubescence QTL o chromosome 10. Both candidate genes for P. capsici resistance and the linkages between resistance and horticultural traits could be applied for selection to broad resistance to P. capsici in bell pepper-breeding programs. [ABSTRACT FROM AUTHOR]

SYP-14288 is a novel fungicide developed by the Shenyang Research Institute of Chemical Industry in China. Although preliminary studies indicate that SYP-14288 is highly effective against 32 important plant pathogens belonging to a range of taxonomic groups, its mode of action remains unknown. In this study, we documented that SYP-14288 has excellent activity against all of the asexual life stages of the plant-pathogenic oomycete Phytophthora capsici , and is especially effective in blocking cyst germination and other life stages that require high energy consumption. In assays designed to determine the fungicide's mode of action, addition of ATP reduced SYP-14288 inhibition of P. capsici , which suggested that SYP-14288 inhibits ATP synthesis of the pathogen. This inference was confirmed in that treatment with SYP-14288 sharply reduced the ATP content in P. capsici . The respiration rate of P. capsici was positively correlated with the concentration of SYP-14288 or of the fungicide fluazinam (an uncoupler of oxidative phosphorylation), but increases in respiration were greater with SYP-14288 than with fluazinam. These results indicate that SYP-14288 is a promising fungicide that functions as an uncoupler of oxidative phosphorylation. [ABSTRACT FROM AUTHOR]

Phytophthora diseases cause billions of dollars annually in damage to crops. Nanotechnology provides various metallic nanoparticles exhibiting a strong activity against microbial pathogens. Silver nanoparticles-based products are outstanding samples, which has been produced in large scale and performed well with a high activity against several fungal pathogens. Our previous study indicated oligochitosan-coated silver nanoparticles (OCAgNPs) which were prepared from 3,4 dihydroxyphenyl acetic acid - conjugated oligochitosan and silver nitrate salt performed an enhancement in antibacterial ability at a very low concentration. Objective of this study was to determine the effect of the OCAgNPs on growth and reproduction of Phytophthora capsici, P. nicotianae and P. colocasiae in vitro. The study shown that strong inhibition of mycelial growth, sporangium production, zoospore release and zoospore germination of P. capsici, P. nicotianae and P. colocasiae occurred when exposed to at 9 ppm of OCAgNP. The results demonstrated a great potential of OCAgNPs for controlling growth of Phytophthora. [ABSTRACT FROM AUTHOR]

The efforts to signify the relevance of tRNA modifications were always within the limits of prokaryotes, humans, and some fewer model plant systems. The story of tRNA modifications in higher plants is still overlooked, especially in non-model spice crops. Stress causes alterations in tRNA modifications to facilitate the downstream functions of tRNAs. The present study was done to identify and better understand the fate of tRNA nucleoside modifications during biotic stress response in a widely used spice crop called Black pepper. We have uncovered the various tRNA nucleoside modifications present in black pepper. Methylations were the predominant nucleoside modifications in black pepper tRNAs. Furthermore, the different methyltransferase gene candidates implicated in catalyzing tRNA nucleoside methylations in black pepper were also identified. The LC-MS profile showed that certain tRNA nucleoside modifications showed varied abundance upon P. capsici infection. The N4-acetylcytidine (ac4C) nucleoside modification has shown a constant hike at 24 and 48 hpi. At the same time, some nucleoside modifications have exhibited a time-dependent abundance. Altogether our study suggests that tRNA modifications and the expression of associated enzymes are altered during biotic stress regulation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.)

Molecular identification of the Phytophthora spp. affecting betelvine ( Piper betel), brinjal ( Solanum melongena), guava ( Psidium guajava), roselle ( Hibiscus subdariffa), black pepper ( Piper nigrum), sesame ( Sesamum indicum), taro (Colocasia esculenta), chilli ( Capsicum annuum), pointed gourd ( Trichosanthes dioica), papaya ( Carica papaya) was performed through rDNA ITS-RFLP and also additionally by sequencing the Internal Transcriber spacer (ITS) ITS1 and ITS2 regions. Phytophthora nicotianae, Phytophthora capsici, Phytophthora colocasiae, Phytophthora melonis and Phytophthora palmivora isolates from these 10 different crops were accessioned and the ITS sequences were deposited in Genbank. ITS sequences for Phytophthora isolates from most of these crops are being reported here for the first time. In this study, a review of all earlier Indian reports based on morphology from the above crops and their molecular corroboration has been attempted. This study revealed that not only is P. nicotianae the most prevalent species but also there is the presence of both P. nicotianae and P. capsici, but not P. palmivora on betelvine; as well as possible first reports of P. nicotianae on pepper, P. capsici on chilli and P. palmivora on papaya from this vegetable growing Eastern region of the country. Mating type assays and RAPD markers were used to assess the genotypic diversity of the population. This detection of diversity is a first and critical step for helping to devise and adopt strategies for control and quarantine of these pathogens in this region. [ABSTRACT FROM AUTHOR]

Isolates of Phytophthora from pepper, produced in Tunisia, were characterised according to molecular and pathogenicity criteria. Polymerase chain reaction amplification of the ITS1 region in the ribosomal DNA resulted in different sized fragments. The pepper isolates and P. nicotianae yielded a fragment of 310 bp that distinguished it from P. capsici with a fragment of 270 bp. The ribosomal RNA gene amplicons of both internal transcribed spacers and the 5.8 S of the pepper Phytophthora and P. nicotianae were digested with 8 endonucleases. The patterns generated, with the 2 enzymes that cut, were identical for both taxa. This molecular analysis corroborated the morphological and biological characteristics and suggests strongly that the isolates of Phytophthora from pepper belong to the species P. nicotianae. Inoculation of pepper, tomato, eggplant and tobacco plants with the isolates of P. nicotianae from pepper showed they were highly pathogenic on pepper but not on tobacco, while their pathogenicity was weak on tomato and eggplant and was associated with atypical symptoms not observed in the field. These pathogenicity tests suggest that pepper isolates of P. nicotianae are particularly adapted to their host and may thus constitute a forma specialis of P. nicotianae. [ABSTRACT FROM AUTHOR]

• Isolates of three Bacillus species suppressed growth of Phytophthora capsici invitro. • The isolates suppressed P. capsici disease severity in phytophthora-infested soil. • Two isolates suppressed disease and promoted plant growth better than fungicide. • Some isolate mixtures suppressed disease and promoted plant growth similar to fungicide metalaxyly. Phytophthora capsici is one of the most important pathogens impacting the production of horticultural crops including pepper (Capsicum annuum). Pepper growers rely heavily on pesticides, but toxicity hazards to farm-workers, consumers, non-target organisms as well as environmental contamination cause great concern. Furthermore, the development of pesticide resistance is problematic. The objective of this study was to evaluate isolates of three Bacillus spp. [ B. vallismortis (Ps), B. amyloliquefaciens (PsL) and B. thuringiensis (IMC8)] as biological control agents for P. capsici disease management. These isolates inhibited P. capsici mycelial growth invitro and reduced P. capsici disease severity in plants grown in Phytophthora -infested soil in greenhouse environment. In addition, the three bacterial isolates promoted plant growth by increasing plant height, shoot weight, root length, root weight and chlorophyll content. Out of the three isolates, PsL displayed the best potential in reducing P. capsici disease severity and in promoting plant growth in Phytophthora -infested soil and both PsL and Ps were significantly better than the fungicide metalaxyl (Ridomil®, Syngenta, Greensboro, NC) in reducing disease severity and promoting plant growth in greenhouse environment. In addition, mixtures of IMC8 + Ps, IMC8 + PsL and IMC8 + Ps + PsL reduced P. capsici disease severity and promoted plant growth similar to the fungicide metalaxyl used at label recommended rates. These three isolates IMC8, Ps and PsL displayed potential as alternative products for disease management and C. annuum plant growth promotion. [ABSTRACT FROM AUTHOR]

Biological control of plant pathogens is considered as one of the green and effective technologies using beneficial microorganisms or microbial secondary metabolites against plant diseases, and so microbial natural products have played important roles in the research and development of new and green agrochemicals. To explore the potential applications for natural γ-lactam alkaloids and their derivatives, 26 γ-lactams that have flexible substituent patterns were synthesized and characterized, and their in vitro antifungal activities against eight kinds of plant pathogens belonging to oomycetes, basidiomycetes, and deuteromycetes were fully evaluated. In addition, the high potential compounds were further tested using an in vivo assay against Phytophthora blight of pepper to verify a practical application for controlling oomycete diseases. The potential modes of action for compound D1 against Phytophthora capsici were also investigated using microscopic technology (optical microscopy, scanning electron microscopy, and transmission electron microscopy) and label-free quantitative proteomics analysis. The results demonstrated that compound D1 may be a potential novel fungicidal agent against oomycete diseases (EC 50 = 4.9748 μg·mL -1 for P. capsici and EC 50 = 5.1602 μg·mL -1 for Pythium aphanidermatum ) that can act on steroid biosynthesis, which can provide a certain theoretical basis for the development of natural lactam derivatives as potential antifungal agents.

Phytophthora blight is one of the most destructive diseases of pepper (Capsicum annuum L.) globally. The APETALA2/Ethylene Responsive Factors (AP2/ERF) genes play a crucial role in plant response to biotic stresses but, to date, have not been studied in the context of Phytophthora resistance in pepper. Here, we documented potential roles for the pepper CaAP2/ERF064 gene in inducing cell death and conferring resistance to Phytophthora capsici (P. capsici) infection. Results revealed that the N-terminal, AP2 domain, and C-terminal of CaAP2/ERF064 protein is responsible for triggering cell death in Nicotiana benthamiana (N. benthamiana). Moreover, the transcription of CaAP2/ERF064 in plant is synergistically regulated by the Methyl-Jasmonate (MeJA) and ethephon (ET) signaling pathway. CaAP2/ERF064 was found to regulate the expression of CaBPR1, which is a pathogenesis-related (PR) gene of pepper. Furthermore, the silencing of CaAP2/ERF064 compromised the pepper plant resistance to P.capsici by reducing the transcript level of defense-related genes CaBPR1, CaPO2, and CaSAR82, while the ectopic expression of CaAP2/ERF064 in N. benthamiana plant elevated the expression level of NbPR1b and enhanced resistance to P.capsici. These results suggest that CaAP2/ERF064 could positively regulate the defense response against P. capsici by modulating the transcription of PR genes in the plant. [ABSTRACT FROM AUTHOR]