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BACKGROUND: Identifying the DNA-binding specificities of transcription factors (TF) is central to understanding gene networks that regulate growth and development. Such knowledge is lacking in oomycetes, a microbial eukaryotic lineage within the stramenopile group. Oomycetes include many important plant and animal pathogens such as the potato and tomato blight agent Phytophthora infestans, which is a tractable model for studying life-stage differentiation within the group. RESULTS: Mining of the P. infestans genome identified 197 genes encoding proteins belonging to 22 TF families. Their chromosomal distribution was consistent with family expansions through unequal crossing-over, which were likely ancient since each family had similar sizes in most oomycetes. Most TFs exhibited dynamic changes in RNA levels through the P. infestans life cycle. The DNA-binding preferences of 123 proteins were assayed using protein-binding oligonucleotide microarrays, which succeeded with 73 proteins from 14 families. Binding sites predicted for representatives of the families were validated by electrophoretic mobility shift or chromatin immunoprecipitation assays. Consistent with the substantial evolutionary distance of oomycetes from traditional model organisms, only a subset of the DNA-binding preferences resembled those of human or plant orthologs. Phylogenetic analyses of the TF families within P. infestans often discriminated clades with canonical and novel DNA targets. Paralogs with similar binding preferences frequently had distinct patterns of expression suggestive of functional divergence. TFs were predicted to either drive life stage-specific expression or serve as general activators based on the representation of their binding sites within total or developmentally-regulated promoters. This projection was confirmed for one TF using synthetic and mutated promoters fused to reporter genes in vivo. CONCLUSIONS: We established a large dataset of binding specificities for P. infestans TFs, representing the first in the stramenopile group. This resource provides a basis for understanding transcriptional regulation by linking TFs with their targets, which should help delineate the molecular components of processes such as sporulation and host infection. Our work also yielded insight into TF evolution during the eukaryotic radiation, revealing both functional conservation as well as diversification across kingdoms.

Phytophthora infestans is a major oomycete plant pathogen, responsible for potato late blight, which led to the Irish Potato Famine from 1845–1852. Since then, potatoes resistant to this disease have been bred and deployed worldwide. Their resistance (R) genes recognize pathogen effectors responsible for virulence and then induce a plant response stopping disease progression. However, most deployed R genes are quickly overcome by the pathogen. We use targeted sequencing of effector and R genes on herbarium specimens to examine the joint evolution in both P. infestans and potato from 1845–1954. Currently relevant effectors are historically present in P. infestans, but with alternative alleles compared to modern reference genomes. The historic FAM-1 lineage has the virulent Avr1 allele and the ability to break the R1 resistance gene before breeders deployed it in potato. The FAM-1 lineage is diploid, but later, triploid US-1 lineages appear. We show that pathogen virulence genes and host resistance genes have undergone significant changes since the Famine, from both natural and artificial selection. The joint evolution in Phytophthora infestans and potato over a one hundred period since the Famine is examined based on targeting sequencing of pathogen effector genes and host resistance genes from historic outbreak samples present in plant herbaria. [ABSTRACT FROM AUTHOR]

Late blight, caused by the oomycete Phytophthora infestans, is a devastating disease of potato worldwide. In Israel, potatoes are grown twice a year, in autumn and spring, with late blight causing extensive damage in both seasons. While tuber seeds for the autumn planting are produced locally, seed tubers for the spring planting are imported from Europe due to dormancy of local tubers. Here, we demonstrate that seed tubers imported from Europe for the spring season carry asymptomatic infection with EU genotypes of P. infestans, which alters the population structure of the pathogen each spring. The proportion of imported tubers carrying asymptomatic infections ranged between 1.2 and 3.75%, varying by year and cultivar. Asymptomatic tubers produced late blight-infected sprouts about one month after planting. The sporangia produced on these sprouts served as primary inoculum, causing intensive foliage attacks on neighboring plants. When sprout-infected plants were uprooted and the mother tuber was washed, sliced, and placed in moistened dishes at 18 °C, profuse sporulation of P. infestans developed on the slices' surfaces within 1–2 days. The dominant genotype of P. infestans in the autumn season in Israel is 23A1, but genotypes in the following spring season changed to include 13A2 or 36A2. Surprisingly, genotype 43A1, which might be resistant to CAA and OSBPI fungicides and appeared in Europe in 2022, emerged in Israel in spring 2024. The immigrating genotypes do not persist in the country, allowing 23A1 to regain predominance in the following autumn. Long-term monitoring data suggest that the population structure of P. infestans changes yearly but temporarily due to the import of new genotypes from Europe. [ABSTRACT FROM AUTHOR]

Fungicide resistance to crop protection products is a critical sustainability issue in modern agriculture that requires constant monitoring of the field situation considering different environmental conditions and agricultural practices. Regulation strategies based on resistance risk ranking of both pathogen and active compound, underpinned by fast and broad field monitoring, shall result in recommendations for suitable practices with the aim to stabilize or even to restore the sensitivity situation. Alternating and mixing various products according to their modes of action belong to the most common and the most efficient mitigation methods. Though, these resistance management measures can be implemented best when precise knowledge of both the molecular target and the cell biology of the pathogen as well as of the resistance mechanism is acknowledged. To this end, we have investigated the molecular target and cellular effects of fluopicolide, one of the most effective Oomyceticides in the market. By combining data of genomic analysis of resistant field isolates of Plasmopara viticola and Phytophthora infestans with UV-mutagenized strains of P. infestans, we identified the enzyme vacuolar H+-ATPase as the target protein. Biochemical assays confirmed that fluopicolide inhibits specifically Oomycetes targets and has no residual activity on true fungi or insect orthologs. [ABSTRACT FROM AUTHOR]

Potato and tomato are grown in all Canadian provinces and contribute billions of dollars in exports and sales. Late blight, caused by Phytophthora infestans, is a destructive disease of potato and tomato worldwide and is responsible for millions of dollars in losses annually. Changes in pathogen strains were reported to be associated with late blight epidemics in several regions and pose challenges to late blight management. In British Columbia (BC), diverse strains of P. infestans were reported. Using multiplex microsatellite or simple sequence repeat (SSR) markers, we identified the new genotype US17 of P. infestans from samples of potato and tomato with late blight in BC. All isolates were of the A1 mating type. One, five, and one isolates were sensitive, moderately resistant, and highly resistant to metalaxyl-m, respectively. This is the first report of the occurrence of the US17 genotype in BC and Canada. The US17 strain was also able to cause tuber rot and foliar blight symptoms in potato in pathogen-inoculated assays. [ABSTRACT FROM AUTHOR]

Premise Methods Results Discussion The prompt categorization of Phytophthora infestans isolates into described clonal lineages is a key tool for the management of its associated disease, potato late blight. New isolates of this pathogen are currently classified by comparing their microsatellite genotypes with characterized clonal lineages, but an automated classification tool would greatly improve this process. Here, we developed a flexible machine learning–based classifier for P. infestans genotypes.The performance of different machine learning algorithms in classifying P. infestans genotypes into its clonal lineages was preliminarily evaluated with decreasing amounts of training data. The four best algorithms were then evaluated using all collected genotypes.mlpML, cforest, nnet, and AdaBag performed best in the preliminary test, correctly classifying almost 100% of the genotypes. AdaBag performed significantly better than the others when tested using the complete data set (Tukey HSD P < 0.001). This algorithm was then implemented in a web application for the automated classification of P. infestans genotypes, which is freely available at https://github.com/cpatarroyo/genotypeclas.We developed a gradient boosting–based tool to automatically classify P. infestans genotypes into its clonal lineages. This could become a valuable resource for the prompt identification of clonal lineages spreading into new regions. [ABSTRACT FROM AUTHOR]

Summary: Potato (Solanum tuberosum) is the fourth largest food crop in the world. Late blight, caused by oomycete Phytophthora infestans, is the most devastating disease threatening potato production. Previous research has shown that StRFP1, a potato Arabidopsis Tóxicos en Levadura (ATL) family protein, positively regulates late blight resistance via its E3 ligase activity. However, the underlying mechanism is unknown.Here, we reveal that StRFP1 is associated with the plasma membrane (PM) and undergoes constitutive endocytic trafficking. Its PM localization is essential for inhibiting P. infestans colonization. Through in vivo and in vitro assays, we investigated that StRFP1 interacts with two sugar transporters StSWEET10c and StSWEET11 at the PM.Overexpression (OE) of StSWEET10c or StSWEET11 enhances P. infestans colonization. Both StSWEET10c and StSWEET11 exhibit sucrose transport ability in yeast, and OE of StSWEET10c leads to an increased sucrose content in the apoplastic fluid of potato leaves. StRFP1 ubiquitinates StSWEET10c and StSWEET11 to promote their degradation.We illustrate a novel mechanism by which a potato ATL protein enhances disease resistance by degrading susceptibility (S) factors, such as Sugars Will Eventually be Exported Transporters (SWEETs). This offers a potential strategy for improving disease resistance by utilizing host positive immune regulators to neutralize S factors. [ABSTRACT FROM AUTHOR]

Late Blight, also called Irish blight and brown rot, devastated potato crops in Ireland and countries in Europe in the 1840s, and led to famines, deaths, and the emigration of tens of thousands of poor farmworkers. The outbreaks were blamed on many factors, but finally it was demonstrated that the causal agent was an oomycete (water mould) Phytophthora infestans. The Queensland Government Entomologist and Vegetable Pathologist, Henry Tryon, claimed that he made the first discovery of Late Blight in Australia, on leaves and tubers of potato collected in May 1909 around Brisbane. Within three months, the disease was found in all Australian states. Tryon believed that the Queensland outbreak was caused by Phytophthora -infected planting tubers obtained from Tasmania, which growers and the government in that state initially refused to acknowledge. The Victorian Vegetable Pathologist, Daniel McAlpine, initially agreed with the Tasmanians, but later admitted that he had identified Ph. infestans in Tasmanian potato crops. A herbarium specimen of potato leaves collected in 1900 in Victoria, examined over a century later, was found to be infected with Phytophthora infestans. All the ruckus that ensued after Tryon's discovery was unnecessary; it was really a matter of where and when. Late blight, ultimately shown to be caused by the oomycete Phytophthora infestans , devastated potato crops in Ireland and other countries in Europe during the mid-late 1840s. In 1909 the disease was positively identified in Australia by the Queensland Vegetable Pathologist, Henry Tryon, who had compelling evidence that the source of the disease outbreaks was planting tubers from Tasmania. Growers and authorities in that state refused to believe the accusation but were soon proved wrong. Image credit: J. M. Berkeley (1846). [ABSTRACT FROM AUTHOR]

In recent years, skin blemish diseases of potato (including black dot (BD) caused by Colletotricum coccodes) have begun to be important for global potato marketing, since consumers often reject tubers with an imperfect appearance, which results in financial losses caused by the disposal of unwanted potatoes. Like for many non-fatal plant diseases, BD severity may depend on the immune status of plants influenced by other infectious agents. Using a set of 98 potato cultivars differing in their late blight (LB) resistance, we examined the correlation between the intensity of their infection with LB determined by their LB resistance and the occurrence of the BD disease under field conditions with a high background level of both diseases. Using LB-susceptible (Arizona) and moderately susceptible (Sante) cultivars, we also evaluated the effect of a crop protection against LB on BD development under the same field conditions. A strong negative correlation (r = −0.81, p < 0.05) between the LB resistance and the BD occurrence has been revealed. An experiment using the two cultivars, chemically protected against LB, showed a significant reduction in BD occurrence of 30% (cv. Arizona) and 20% (cv. Sante) compared to the untreated controls; the total yield and marketability of potatoes increased by 103.6 and 62.5% for cv. Arizona and by 65.9 and 43.8% for cv. Sante. The reduction in the LB affection of potato is one of the key factors improving the immune status of potato cultivars in relation to BD infection, so methods of LB protection should be included in a complex approach to BD control. [ABSTRACT FROM AUTHOR]

Late blight (LB) caused by Phytophthora infestans (Mont.) de Bary, is one of the most destructive diseases of potato and tomato worldwide. Globally, application of fungicide is an effective approach for potato LB management. Isolates of P. infestans were collected from different fields in Egypt and characterized using microsatellite markers and mitcondrial DNA. Twelve fungicides were applied in vitro to test their control P. infestans isolates. Nine potato cultivars were evaluated under artificial inoculation. Field trials were conducted to evaluate the efficacy of applied fungicides to LB management and potato productivity at El-Behera governorate in two seasons. Our results revealed that collected isolates of P. infestans were A1 mating type, 23_A1 clonal lineage and Ia/IR1 mitcondrial DNA. Furthermore, potato cultivar Burren was highly resistant and recorded the lowest area under disease progress curve (AUDPC). On the other hand, cultivars Alaska, Spunta, Lady Rosita and Mondial were highly susceptible and revealed the highest AUDPC values. In vitro, all fungicide applications inhibited linear growth of P. infestans isolates (EG-Pi1 and EG-Pi2). For field trial, Equation-Pro, and Consonto were the most effective fungicides in respect of LB management where lowest disease severity and AUDPC were recorded in both prophylactically and curatively during two seasons. Moreover, potato tuber production significantly increased with Equation -- Pro application. The results of this study provided crucial information for potato breeding programs and crop improvement as well as successful management strategy for late blight challenge. [ABSTRACT FROM AUTHOR]

Summary: Potato is the third most important food crop worldwide. Potato production suffers from severe diseases caused by multiple detrimental plant pathogens, and broad‐spectrum disease resistance genes are rarely identified in potato. Here we identified the potato non‐specific lipid transfer protein StLTPa, which enhances species none‐specific disease resistance against various pathogens, such as the oomycete pathogen Phytophthora infestans, the fungal pathogens Botrytis cinerea and Verticillium dahliae, and the bacterial pathogens Pectobacterium carotovorum and Ralstonia solanacearum. The StLTPa overexpression potato lines do not show growth penalty. Furthermore, we provide evidence that StLTPa binds to lipids present in the plasma membrane (PM) of the hyphal cells of P. infestans, leading to an increased permeability of the PM. Adding of PI(3,5)P2 and PI(3)P could compete the binding of StLTPa to pathogen PM and reduce the inhibition effect of StLTPa. The lipid‐binding activity of StLTPa is essential for its role in pathogen inhibition and promotion of potato disease resistance. We propose that StLTPa enhances potato broad‐spectrum disease resistance by binding to, and thereby promoting the permeability of the PM of the cells of various pathogens. Overall, our discovery illustrates that increasing the expression of a single gene in potato enhances potato disease resistance against different pathogens without growth penalty. [ABSTRACT FROM AUTHOR]

Management of late blight relies on the use of fungicides and potato varieties which have been associated with loss of efficacy over time. Baseline survey and field studies were conducted to evaluate the effects of fungicide formulations and potato varieties in managing late blight and subsequently on net farm income improvement. Four fungicides formulations (Infinito® (Fluopicolide 62.5g L−1 + propamocarb 625 g L−1), Milraz® (Propineb 700 g kg−1 + cymoxanil 60 g kg−1), Mistress 72® (Mancozeb 640 g kg−1 + cymoxanil 80 g kg−1) and Ridomil® (Metalaxyl 40 g kg−1 + mancozeb 640 g kg−1)), and varieties (Kenya Mpya, Shangi and Dutch Robijn) were evaluated. Survey results revealed that the majority (78%) of the farmers selected varieties to grow based on market dynamics as compared to seed availability (18%), disease resistance (12%) and other factors (8%). The most widely and least used fungicides were Ridomil® (28.8%) and Infinito® (1.7%) respectively. Late blight significantly reduced crop growth (height and stem count) and yield in the unprotected plots in Shangi and Dutch Robijn, but no effect was observed in K. Mpya. Mistress® suppressed blight symptoms by 54%, while Milraz® (lowest effects) reduced the disease by (43%). In unprotected plots, disease severity on K. Mpya was below 1%, while in Shangi and Dutch Robijn varieties, it was 60 and 78% respectively. Reduction in disease by Mistress® resulted in higher yield (30.70 t ha−1) as compared to the unprotected plots (9.25 t ha−1). Maximum yield (28.56 t ha−1) was obtained from K. Mpya, while Dutch Robijn, had the lowest observed yield (20.70 t ha−1) in protected plots. Yet, the highest cost benefit ratio (CBR) was recorded in unprotected plots with K. Mpya. The smallest CBR (1.55) was observed on plots where Milraz® was applied on Dutch Robjn. Results of this study show that, the use of fungicides reduced late blight and improved yield of potato substantially, but the efficacy varied with fungicide formulation and potato variety. However, the use of resistant variety was effective in managing late blight hence a useful tool for minimizing fungicide applications. Therefore, use of resistant variety could enhance a healthy biodiversity and at the same time maximize food production. [ABSTRACT FROM AUTHOR]

Abstract Background Identifying the DNA-binding specificities of transcription factors (TF) is central to understanding gene networks that regulate growth and development. Such knowledge is lacking in oomycetes, a microbial eukaryotic lineage within the stramenopile group. Oomycetes include many important plant and animal pathogens such as the potato and tomato blight agent Phytophthora infestans, which is a tractable model for studying life-stage differentiation within the group. Results Mining of the P. infestans genome identified 197 genes encoding proteins belonging to 22 TF families. Their chromosomal distribution was consistent with family expansions through unequal crossing-over, which were likely ancient since each family had similar sizes in most oomycetes. Most TFs exhibited dynamic changes in RNA levels through the P. infestans life cycle. The DNA-binding preferences of 123 proteins were assayed using protein-binding oligonucleotide microarrays, which succeeded with 73 proteins from 14 families. Binding sites predicted for representatives of the families were validated by electrophoretic mobility shift or chromatin immunoprecipitation assays. Consistent with the substantial evolutionary distance of oomycetes from traditional model organisms, only a subset of the DNA-binding preferences resembled those of human or plant orthologs. Phylogenetic analyses of the TF families within P. infestans often discriminated clades with canonical and novel DNA targets. Paralogs with similar binding preferences frequently had distinct patterns of expression suggestive of functional divergence. TFs were predicted to either drive life stage-specific expression or serve as general activators based on the representation of their binding sites within total or developmentally-regulated promoters. This projection was confirmed for one TF using synthetic and mutated promoters fused to reporter genes in vivo. Conclusions We established a large dataset of binding specificities for P. infestans TFs, representing the first in the stramenopile group. This resource provides a basis for understanding transcriptional regulation by linking TFs with their targets, which should help delineate the molecular components of processes such as sporulation and host infection. Our work also yielded insight into TF evolution during the eukaryotic radiation, revealing both functional conservation as well as diversification across kingdoms.

In this study, we present a method for isolation and propagation of Phytophthora infestans, a challenging-to-isolate phytopathogenic oomycete. The procedure initiated with naturally infected potato leaves, which underwent a 30-minute sanitization under running water. Subsequently, healthy potato tubers were meticulously washed with a neutral detergent, sterilized using alcohol, and then flamed. Slices 4 mm thick were carefully cut out of the potato tubers. Slices were used to cover 2 x 4 mm sterilized leaf pieces cut from the border of two-day old young P. infestans lesions, within sterilized empty Petri dishes. The sealed plates were then transferred to BOD growth chambers set at 18 ºC in complete darkness for 5 days. At the end of this incubation period, the development of a sparse, white mycelium was observed on top of the potato slices. Using a Drigalski loop, the visible mycelium was carefully transferred to rye agar medium in Petri dishes. To avoid contamination, care was taken not no touch potato slices. After mycelium reaching the Petri dish border, and with aid of a Neubauer chamber, the inoculum density per plate was of 1.79 x 104 sporangia mL-1. Sporangia germination rate ranged from 69 to 78%. This isolation technique simplify in vitro production of P. infestans, enhancing the possibility for research with this important pathogen. [ABSTRACT FROM AUTHOR]

Late blight, caused by the pathogen Phytophthora infestans is an economical disease of potato worldwide. To better understand mechanisms of potato to resist this fungus, pathway signaling of TUB and PR5 were monitored using quantitative real-time PCR (qPCR) across four time points post infection. Results demonstrated that significant variance in the expression profiles of both genes in infected potato plants as compared to the non-infected controls. It is also notable that TUB and PR5 genes have a higher and faster expression in the resistant cultivar ‘Spunta’ as compared to the susceptible one ‘Draga’ with a maximum expression for TUB (1.8 and 1.4-fold) and PR5 (3.5 and 1.2-fold) respectively, at 48 hours post infection. Our data suggest that TUB and PR5 genes, positively regulate P. infestans—resistance in potato plants during disease progress, which can provide testable hypotheses that will need direct future experiments to define how these pathway signaling of both genes may be specified in potato defense system.

The cultivation of potatoes in Indonesia faces challenges, particularly a decline in production attributed to the devastating impact of late blight caused by the fungus P. infestans. Traditional control methods involve the frequent use of chemical pesticides, which pose environmental and health risks. To address this, the research aimed to assess the efficacy of biofungicide containing Trichoderma sp. as a biological agent in controlling late blight on potatoes. The study, conducted in Sumberbrantas Village, Bumiaji District, Batu City, East Java, and the plant disease laboratory at Brawijaya University from January to April 2023, employed both in vivo and in vitro experiments. A Randomized Block Design (RBD) was used for in vivo research, while a Completely Randomized Design (CRD) was employed for in vitro studies, each comprising five concentration treatments with five repetitions. Parameters such as disease intensity, efficacy level, potato production, and biofungicide inhibition were observed. Analysis of variance and the Tukey Honestly Significant Difference (HSD) test were applied to the data and processed using Microsoft Excel. The results indicated that biofungicide with Trichoderma sp. concentrations of 6 ml/l, 4.5 ml/l, 3 ml/l, and 1.5 ml/l effectively reduced the intensity of late blight on potatoes, with efficacy levels exceeding 50%. The highest potato production occurred with a concentration of 6 ml/l, yielding 15.44 tons/ha, followed by 14.67 tons/ha for the 4.5 ml/l concentration. The biofungicide with a concentration of 6 ml/l exhibited the lowest disease intensity at 14.28% and the highest efficacy at 83.08%. Inhibition tests demonstrated that concentrations of 6 ml/l and 4.5 ml were highly effective, inhibiting P. infestans growth by an average of 62.04% and 59.90%, respectively. These findings highlight the potential of biofungicide with Trichoderma sp. in managing late blight on potatoes, providing a sustainable and environmentally friendly alternative to chemical pesticides.

Late blight, caused by Phytophthora infestans, is a major potato disease globally, leading to significant economic losses of $6.7 billion. To address this issue, we evaluated the antifungal activity of ZnO and CuO nanoparticles (NPs) against P. infestans for the first time in laboratory and greenhouse conditions. Nanoparticles were synthesized via a chemical precipitation method and characterized using various techniques. The XRD results revealed that the synthesized ZnO nanoparticles had a pure hexagonal wurtzite crystalline structure, whereas the CuO NPs had a monoclinic crystalline structure. TEM images confirmed the synthesis of quasi-spherical nanoparticles with an average size of 11.5 nm for ZnO NPs and 24.5 nm for CuO NPs. The UV–Vis Spectral Report showed peaks corresponding to ZnO NPs at 364 nm and 252 nm for CuO NPs.In an in vitro study, both ZnO and CuO NPs significantly (p < 0.05) inhibited the radial growth of P. infestans at all tested concentrations compared to the untreated control. The highest inhibitory effect of 100% was observed with ZnO and CuO NPs at 30 mg/L. A lower inhibition of 60.4% was observed with 10 mg/L CuO NPs. Under greenhouse conditions, 100 mg/L ZnO NPs was the most effective treatment for controlling potato late blight, with an efficacy of 71%. CuO NPs at 100 mg/L followed closely, with an efficacy of 69%. Based on these results, ZnO and CuO NPs are recommended as promising eco-friendly fungicides for the management and control of potato late blight after further research. [ABSTRACT FROM AUTHOR]

With the development of genome editing technologies, editing susceptible genes is a promising method to modify plants for resistance to stress. NPH3/ RPT2-LIKE1 protein (NRL1) interacts with effector Pi02860 of Phytophthora infestans and creates a protein complex, promoting the proteasome-mediated degradation of the guanine nucleotide exchange factor SWAP70. SWAP70, as a positive regulator, enhances cell death triggered by the perception of the P. infestans pathogen-associated molecular pattern (PAMP) INF1. Using a clustered regularly interspaced short palindrome repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system, a construct was made to introduce four guide RNAs into the potato cultivar Agria. A total of 60 putative transgenic lines were regenerated, in which 10 transgenic lines with deletions were selected and analyzed. A mutant line with a four-allelic knockdown of StNRL1 gene was obtained, showing an ~90% reduction in StNRL1 expression level, resulting in enhanced resistance to P. infestans. Surprisingly, mutant lines were susceptible to Alternaria alternata, suggesting that StNRL1 may play a role as a resistance gene; hence, silencing StNRL1 enhances resistance to P. infestans. [ABSTRACT FROM AUTHOR]

This document provides a list of references to scientific articles on various topics related to iron oxide nanoparticles, the management of plant diseases caused by Phytophthora infestans, the phylogeny of Mentha spicata, and the use of plant extracts in nanoparticle synthesis. The articles cover subjects such as biotechnology, cancer diagnosis and treatment, antimicrobial activity, and environmental applications. It is worth noting that one of the references has been retracted. [Extracted from the article]

Continued climate change impose multiple stressors on crops, including pathogens, salt, and drought, severely impacting agricultural productivity. Innovative solutions are necessary to develop resilient crops. Here, using quantitative potato proteomics, we identify Parakletos, a thylakoid protein that contributes to disease susceptibility. We show that knockout or silencing of Parakletos enhances resistance to oomycete, fungi, bacteria, salt, and drought, whereas its overexpression reduces resistance. In response to biotic stimuli, Parakletos-overexpressing plants exhibit reduced amplitude of reactive oxygen species and Ca2+ signalling, and silencing Parakletos does the opposite. Parakletos homologues have been identified in all major crops. Consecutive years of field trials demonstrate that Parakletos deletion enhances resistance to Phytophthora infestans and increases yield. These findings demark a susceptibility gene, which can be exploited to enhance crop resilience towards abiotic and biotic stresses in a low-input agriculture. Crop production is threatening by multiple stressors. Here, the authors report the identification of a thylakoid protein encoding gene and show that knocking out this gene results in enhanced resistance to oomycete, fungi and bacteria, as well as increased tolerance to salt and drought mimics in potato. [ABSTRACT FROM AUTHOR]

Phytophthora infestans (Peronosporaceae, Oomycota) is the causal agent of late blight of potato (Solanum tuberosum) and a native to Central America. When introduced to Europe, it rapidly spread in 1845, triggering the Irish Potato Famine, which claimed millions of lives and led to an exodus of Europeans to North America. The spread of the species was recently traced using historical specimens from various herbaria. However, there are critical spatial and temporal gaps in the documentation of the early spread of the species. Within the framework of a digitalization and restoration project of the mid-nineteenth century fungus collections of the herbarium of the State Museum of Natural History Karlsruhe, several specimens of Phytophthora infestans from North-East Germany collected in 1853, 1855 and 1856 were discovered. In addition, we revised already deposited material and identified a specimen of Ph. infestans that was collected no later than 1852. These specimens are among the oldest from Central Europe and are now available to the scientific public. Further, we searched for thus far overlooked specimens, using online catalogues. We found specimens from 23 European countries, with the oldest material from western Europe and almost no data from eastern Europe, south-eastern Europe and southern Europe. Our results emphasize the need for archiving and digitizing natural history collections in order to document the historical spread of agricultural and forest pathogens and to better understand current-day epidemic spreads. [ABSTRACT FROM AUTHOR]

As a staple food in many regions in the world, potatoes are the world's fourth most consumed food. In Indonesia, potatoes contribute significantly to horticultural production. One major constraint known not only in Indonesia but also globally is the late blight disease caused by Phytophthora infestans. Several attempts have been developed in order to solve the problem, one being generation of genetically engineered potato resistant to the pathogen. This was performed by overexpressing RB gene, a resistance gene isolated from potato wild species Solanum bulbocastanum, in local cultivar Granola. All hybrid clones tested showed resistance to P. infestans until 45–50 days after planting without fungicide spraying. This review provides detailed information on the molecular studies of genes involved in the pathogen infection, production of genetically engineered parental variety, breeding of local variety with the resistant parent, and biosafety studies until its release under the variety name of Bio Granola. Future research and development of durable resistant potatoes were also pointed out. The introduction of genetically engineered potato Bio Granola offers hope for the global food security of one significant crop with additional advantage of reduced use of fungicides. [ABSTRACT FROM AUTHOR]

Solanum pinnatisectum exhibits strong resistance to late blight caused by Phytophthora infestans but only an incomplete genome assembly based on short Illumina reads has been published. In this study, we generated the first chromosome-level draft genome for the wild-type potato species S. pinnatisectum in China using Oxford Nanopore technology sequencing and Hi-C technology. The high-quality assembled genome size is 664 Mb with a scaffold N50 value of 49.17 Mb, of which 65.87% was occupied by repetitive sequences, and predominant long terminal repeats (42.51% of the entire genome). The genome of S. pinnatisectum was predicted to contain 34,245 genes, of which 99.34% were functionally annotated. Moreover, 303 NBS-coding disease resistance (R) genes were predicted in the S. pinnatisectum genome to investigate the potential mechanisms of resistance to late blight disease. The high-quality chromosome-level reference genome of S. pinnatisectum is expected to provide potential valuable resources for intensively and effectively investigating molecular breeding and genetic research in the future. [ABSTRACT FROM AUTHOR]

Phytophthora infestans (Mont.) de Bary, the oomycotic pathogen responsible for potato late blight, is the most devastating disease of potato production. The primary pesticides used to control oomycosis are phenyl amide fungicides, which cause environmental pollution and toxic residues harmful to both human and animal health. To address this, an antimicrobial peptide, NoPv1, has been screened to target Plasmopara viticola cellulose synthase 2 (PvCesA2) to inhibit the growth of Phytophthora infestans (P. infestans). In this study, we employed AlphaFold2 to predict the three-dimensional structure of PvCesA2 along with NoPv peptides. Subsequently, utilizing computational methods, we dissected the interaction mechanism between PvCesA2 and these peptides. Based on this analysis, we performed a saturation mutation of NoPv1 and successfully obtained the double mutants DP1 and DP2 with a higher affinity for PvCesA2. Meanwhile, dynamics simulations revealed that both DP1 and DP2 utilize a mechanism akin to the barrel-stave model for penetrating the cell membrane. Furthermore, the predicted results showed that the antimicrobial activity of DP1 was superior to that of NoPv1 without being toxic to human cells. These findings may offer insights for advancing the development of eco-friendly pesticides targeting various oomycete diseases, including late blight. [ABSTRACT FROM AUTHOR]

The continuous changes in the lineage proportions of populations in the clonal plant pathogen Phytophthora infestans on potato and tomato crops have been perplexing to researchers and disease managers. Sudden outbreaks of newly emergent genotypes are often associated with these rapid composition changes. Modelling can predict the persistence and displacement of pathogen genotypes with differential fitness among hosts. Building upon previous models, we combined analytical and simulation methods to model the outcome of interactions between competing lineages on different hosts. Model inputs include pathogenesis parameters, and the outputs are fitness and lineage proportions within each host. Analytical solutions yielding complete displacement, partial coexistence‐displacement and complete coexistence were described. In a retrospective study, the lesion growth rate and sporulation density of P. infestans lineages on potato and tomato from pathogenicity trials were used as inputs. Output lineage frequencies were compared with historical epidemiological situations to check model accuracy. The results showed that pathogenesis traits measured from empirical trials could simulate lineage constituents on potato and tomato and estimate genotypic fitness with reasonable accuracy. The model also showed promise in predicting ongoing lineage displacements in the subsequent year or few years, even when the displaced lineage was still highly prevalent during the time of isolation. However, large uncertainties remain at temporal–spatial scales owing to complex meta‐population dynamics in some regions and adaptation to local environmental factors. This simulation model provides a new tool for forecasting pathogen compositions and can be used to identify potentially problematic genotypes based on pathogen life‐history traits. [ABSTRACT FROM AUTHOR]

This two-year research aimed to evaluate the efficacy of chemical preparations and the resistance of tomato cultivars (Amati and Bella) against the Phytophthora infestans pathogen causing fruit blight. Fungicides, including Metalaxyl, Azoxystrobin, Mancozeb, and Copper, were tested in seven combinations, and disease assessments were conducted using the McKinney Index. Results from 2021 and 2022 consistently demonstrated that the combination of Azoxystrobin and Metalaxyl exhibited the highest efficiency in protecting both cultivars against Phytophthora infestans, with infection rates as low as 5.30% and 4.43%, respectively. In addition to fungicide effectiveness, cultivar resistance analysis revealed that Bella consistently displayed higher sustainability to the pathogen compared to Amati, with infection rates ranging from 4.43% to 6.30% for Bella, compared to 5.30% to 7.03% for Amati. This enhanced resistance in Bella was attributed to its smaller vegetative mass. The study underscores the importance of meticulous systemic fungicide use to prevent the development of pathogen resistance. Furthermore, the research recommends adjusting the frequency of sprayings based on climatic conditions to optimize blight management strategies. This research provides valuable insights into effective blight management strategies, highlighting specific fungicide combinations, and emphasizing the resistance characteristics of tomato cultivars. These findings contribute to the development of sustainable practices for protecting tomatoes against Phytophthora infestans, ultimately aiding in the cultivation of more resilient and disease-resistant tomato crops. [ABSTRACT FROM AUTHOR]

The NEGFRY system is presented in this research work as a novelty strategy for the control of potato late blight in A Limia (NW Spain). The aim was to analyse the number of fungicide applications established by NEGFRY (Decision Support System, DSS) with respect to the routine calendars of this potato production area. This approach is in accordance with the requirements imposed by European policies, participating in more profitable and environmentally friendly agriculture. For this purpose, the relationships between the pathogen and the environmental conditions and epidemiological parameters were analysed in different plots compared to late blight infection in both Routine and DSS strategies. In addition, economic and environmental impacts of fungicide sprays were also analysed to check the adaptability of the decision support system to late blight in the area. Results confirmed that it is possible to reduce sprays following the NEGFRY model by more than 50% compared with Routine applications. Therefore, NEGFRY is a promising strategy to achieve lower footprint potato yields through a reduction in applied pesticides and water, lower gas emissions and less soil compaction due to a reduction in the number of tractor passes over the soil. The commitment to this strategy contributes to improving the economy of farmers, the health of the biodiversity, the environment and consumers, as well as to comply with demands of global economies in terms of more sustainable and resilient agriculture. [ABSTRACT FROM AUTHOR]

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Two novel sesquiterpene derivatives, dendocarbin B (1), bisaborosaol C (2), and nine known compounds (3-11), were isolated from Nigrospora chinensis GGY-3 derived from Ilex cornuta. The structures of new compounds were elucidated using HR-ESI-MS, 1 D and 2 D NMR spectra, X-ray diffraction analysis as well as ECD calculation and comparison. Compound 1 showed moderate antifungal activities against Rhizoctonia solani and Botrytis cinerea. Compounds 5 and 6 exhibited significant inhibitory activity against Phytophthora capsici, Magnaporthe oryzae and R. solani with EC50 values ranging from 13.91 to 29.49 μg/mL. Compounds 10 and 11 displayed moderate antibacterial effects on Bacillus subtilis and Xanthomonas oryzae pv. oryzae (Xoo), with MIC values of 16-64 μg/mL. Particularly, 11 presented strong antibacterial activity against Staphylococcus aureus with an MIC value of 4 μg/mL (2 μg/mL for streptomycin sulfate). In addition, compound 11 also possessed DPPH radical scavenging capability with an IC50 value of 14.80 μg/mL. [ABSTRACT FROM AUTHOR]

Phytophthora infestans is the causal agent of late blight in potato. The occurrence of P. infestans with both A1 and A2 mating types in the field may result in sexual reproduction and the generation of recombinant strains. Such strains with new combinations of traits can be highly aggressive, resistant to fungicides, and can make the disease difficult to control in the field. Metalaxyl-resistant isolates are now more prevalent in potato fields. Understanding the genetic structure and rapid identification of mating types and metalaxyl response of P. infestans in the field is a prerequisite for effective late blight disease monitoring and management. Molecular and phenotypic assays involving molecular and phenotypic markers such as mating types and metalaxyl response are typically conducted separately in the studies of the genotypic and phenotypic diversity of P. infestans. As a result, there is a pressing need to reduce the experimental workload and more efficiently assess the aggressiveness of different strains. We think that employing genetic markers to not only estimate genotypic diversity but also to identify the mating type and fungicide response using machine learning techniques can guide and speed up the decision-making process in late blight disease management, especially when the mating type and metalaxyl resistance data are not available. This technique can also be applied to determine these phenotypic traits for dead isolates. In this study, over 600 P. infestans isolates from different populations—Estonia, Pskov region, and Poland—were classified for mating types and metalaxyl response using machine learning techniques based on simple sequence repeat (SSR) markers. For both traits, random forest and the support vector machine demonstrated good accuracy of over 70%, compared to the decision tree and artificial neural network models whose accuracy was lower. There were also associations (p < 0.05) between the traits and some of the alleles detected, but machine learning prediction techniques based on multilocus SSR genotypes offered better prediction accuracy. [ABSTRACT FROM AUTHOR]

The application of Chinese herbal medicine to the prevention and control of crop diseases and pests has attracted much attention due to their unique advantages. To explore the efficient Chinese herbal medicine preparations that can be used for controlling Phytophthora infestans, and help green prevention and control of P. infestans, the ternary solvent of anhydrous ethanol, petroleum ether and ethyl acetate (volume ratio 4:3:3) was chosen to extract different parts of 11 Chinese herbal medicines, for instance, Thymus mongolicus, by cold impregnation method to obtain the corresponding preparations. The inhibitive activity of 11 Chinese herbal medicine preparations against P. infestans in vitro and semi in vivo was determined by plate mycelium growth rate and leaf inoculation method, respectively. The preparations of T. mongolicus and Rheum palmatum had strong antibacterial activity, with EC50 of 130.19 and 364.90 mg/kg, respectively, which were much stronger than those of eugenol (669.52 mg/kg). The preparations of Saposhnikovia divaricata, Rumex dentatus, Pogostemon cablin, Cnidium monnieri, Daucus carota and Cullen corylifolium were also strong for antibacterial activity, with EC50 of 768.28, 807.33, 874.75, 953.52, 1 519.11 and 1 659.58 mg/kg, respectively, which were slightly lower or lower than eugenol. It is evident that T. mongolicus, R. palmatum, S. divaricata, R. dentatus, P. cablin, C. monnieri, D. carota and C. corylifolium exhibit strong control effects and potential application value for P. infestans. [ABSTRACT FROM AUTHOR]

The effect of chitosan conjugates with caffeic (ChCA) and ferulic (ChFA) acids in combination with Bacillus subtilis bacteria on the transcriptional activity of PR protein genes and proteome changes in potato plants during infection with Phytophthora infestans (Mont.) de Bary was studied. Plants grown from mini tubers of the Udacha variety were sprayed with solutions of ChCA and ChFA, a suspension of B. subtilis bacteria strains 26D and 11 VM, and conjugates of ChCA of ChFA together with bacteria. At 3 days after treatment, some plants were infected with P. infestans. A decrease in the degree of development of the late blight pathogen on potato leaves in all treatment options was revealed. The maximum protective effect was manifested when plants were treated with the B. subtilis strain 26D bacteria in combination with conjugates of chitosan and oxycinnamic acids. The mechanisms of increasing the resistance of potato plants to P. infestans were associated with the activation of transcriptional activity of genes encoding the main protective protein (PR-1), chitinase (PR-3), thaumatin-like protein (PR-5), protease inhibitor (PR-6), peroxidase (PR-9), and ribonuclease (PR-10). The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of joint treatment of plants with B. subtilis and chitin conjugates with hydroxycinnamic acids indicates the synergistic development of protective reactions in potato plants in this variant. Using the method of two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis 12 proteins were identified; their presence in the leaves differed depending on the variant of the experiment. In all treatment variants, serine–threonine protein phosphatase activity was suppressed, reflecting the development of the hypersensitivity reaction. Different variants of the experiment formed weakly expressed clusters, which indicates multiple mechanisms of regulation of the synthesis of protective proteins involved in the reaction to treatment with bacteria, chitosan conjugates, and infection with P. infestans. [ABSTRACT FROM AUTHOR]

The cultivar Cooperation-88 (C88), developed from the International Potato Center's germplasm, bred in the Philippines and selected in Southwest China, has resistance to late blight, PVY, and PLRV. It is, however, a short-day cultivar and unsuitable for growing conditions in Canada. In 2015 the Canadian Private Potato Breeders Network (CPPBN) made reciprocal crosses between C88 with long day cvs Prospect and Shepody. C88 functioned as both male and female in the trial. Evaluations of progeny of the crosses indicated that some clones inherited resistance to late blight while producing high yields of tubers under long days. This finding reveals the acceptable heredity of resistance in a potato breeding program when a short-day cultivar is crossed with two different long day cultivars. This study meets the collaborative goal of the CPPBN to develop new potato varieties with durable resistance to late blight. [ABSTRACT FROM AUTHOR]

Late blight, caused by Phytophthora infestans, is a serious disease of potatoes worldwide and is predominantly controlled by repeated prophylactic use of fungicides throughout the growing season. Effective blight management and integrated pest management strategies rely on knowledge of the efficacy of available fungicides to control contemporary genotypes of P. infestans. Between 2019 and 2022, representative isolates of the newer dominant genotypes EU36, EU37 and the older dominant genotype EU6 were sampled from GB crops and tested for sensitivity to seven commonly used fungicide active ingredients (cyazofamid, fluopicolide, mandipropamid, propamocarb, oxathiapiprolin, amisulbrom and mancozeb) used preventatively in detached leaf tests and zoospore motility assays where appropriate. Dose–response curves based on lesion area (mm2) were constructed, and EC50 values calculated. Isolates of P. infestans genotype EU37 were insensitive to fluazinam as previously reported. No insensitivity, or progression towards resistance over time, to any of the other fungicides was observed in any isolates of the genotypes tested, and EC50 values were generally in line with previous testing. Zoospore motility tests with fluopicolide revealed significantly higher MIC values for isolates of genotype EU36 compared with EU37 and EU6, which, whilst not indicative of resistance at the low concentrations of active ingredient tested, may be a factor contributing to the overall dominance of that genotype in the wider population of P. infestans. The evidence suggests that the fungicides tested, with the exception of fluazinam and EU37, are effective for the control of P. infestans genotypes dominant in the GB population up until 2022. [ABSTRACT FROM AUTHOR]

This study presents an investigation of the chemical composition and biological activities of the essential oil (EO) extracted from aerial parts of Echinophora chrysantha (EC). Gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of twenty-two components, representing 97.5% of the total oil. Major constituents were determined as α-phellandrene (55.74%), β-phellandrene (17.41%), and p-cymene (8.95%). The EO was screened for antimicrobial and antifungal activity against a panel of bacteria and fungi using a broth micro-dilution and fumigant activity assay, respectively. EO sample exhibited better activity against Listeria monocytogenes, Staphylococcus aureus Enterococcus faecium with 31.25, 31.25, and 62.5 μg/mL MIC values. EOs showed moderate mycelium growth inhibitory activity against Phytophthora infestans (32.9±1.9%), Verticillium dahliae (42.3±1.8%), and Fusarium oxysporum f. sp. lycopersici (53.0±2.9%) at 8 μL/petri concentration. The insecticidal activity of EO was also evaluated against two insects (Rhyzopertha dominica and Tribolium confusum) showing moderate activity with mortality rates of 25.8±0.6% and 37.9±1.2% at a 5% (v/v) concentration. Literature search has not revealed any previous work on the antimicrobial, antifungal, and insecticidal activities of the EO from E. chrysantha. In conclusion, this is the first report describing the biological activities of this plant EOs. Additionally, these findings highlight the practical implications of the utilizing essential oil of EC as a potential natural remedy against a spectrum of microbial threats in both pharmaceutical and food preservation applications. [ABSTRACT FROM AUTHOR]

[Objective) The study aimed to monitor the resistance level of Phytophthora infestans populations on potato towards novel efficient fungicide cyazolamid, investigate its anti-oomycete effect so as to provide scientific reference for the green control of late blight and promote rational utilization of the fungicide. [Method) The sensitivity of P. ingfestans isolates collected from four dominant potato regions China during 2015 to 2020 was determined by fungicide-amended plate method, and the EC50, resistance multiple and resistance index. calculated to assess the resistance level of P. infestans to eyazofamid in China. The inhibitory phenotypes of eyazofamid on different growth and development stages of P. infestons and its effect on pathogenicity were determined in vitro. (Result) The frequency distribution of sensitivity of 160 isolates of P. infestans from 4 dominant regions of China showed a continuous single peak curve, which was normal distribution. The EC, values ranged from 0. 0666 to 3.8498 µg/ml, with an average EC50 value of (0.5286 ±0.5394) µg/ml. The results indicated that P. infestans isolates sensitive to cyazofamid, with a proportion of 89.0%. This suggested that the sensitive isolates of P. infestans were the predominant population. In addition, low-resistance isolates were detected, moderate or high-resistant isolates were detected. The resistance level showed that no significant difference in the average EC50 value and the average resistance multiple of P. infestans to cyazolium among the four dominant potato regions. The resistance frequency than 10% between northern gle-planting region and southwestern mixed planting region. The results showed that cyaofamid significantly inhibited the life stages of P. infestans such as mycelial growth, sporangium formation, direct sporangium germination, zoospore release and cyst germination. This inhibition seriously compromised the pathogenicity of P. infestans. Conclusion] Chinese P. infestans isolates exhibite greater sensitivity to cyanodamid. The resistance index of P. infestans in the four dominant regions is found to be similar and extremely low, indicating a low resistance risk. Cyazofamid inhibites the growth and development of P. infestans, thereby affecting its pathogenicity. [ABSTRACT FROM AUTHOR]

Tomato is a widely cultivated and economically important crop worldwide. This study aimed to test the effect of light spectra used in indoor cultivation on the growth, biochemical profile, and resistance of Solanum lycopersicum 'Bawole Serce' seedlings against Alternaria alternata, Alternaria solani and Botrytis cinerea. During the phase of first leaf emergence, the seedlings were transferred to a semi-sterile growth room with a controlled environment (20°C, 18-h photoperiod, 50 µmol · m-2 · s-1 PPFD, 65% RH) for a 3-week cultivation period. Five light treatments differing in red/blue (R/B) light ratio were tested: I (LED tube; R/B 5.55), II (fluorescent tube; R/B 0.72), III (fluorescent tube; R/B 1.19), IV (LED panel; R/B 0.51), V (LED panel; R/B 0.20). The best parameters in terms of shoot length, shoot fresh and dry weights, and number of leaves were obtained in treatment I, in contrast to IV and V. Plants from treatments IV and V had the smallest leaf area, perimeter, vertical length, and horizontal width. As for the root system, the highest fresh weight, area, length of the longest root, total length, and the number of root tips and forks were found in treatments I and II. The least developed root systems were observed in IV and V. The greatest chlorophyll, carotenoids and anthocyanins accumulation was enhanced by treatment II. Treatments I-III stimulated the biosynthesis of phenolic compounds. The highest superoxide dismutase activity was detected in plants from treatments I and II. As for A. alternata and A. solani, the level of disease symptoms was significantly higher for treatments IV and V than for I-III. The highest/lowest level of B. cinerea infection was found in treatments II/I, respectively. The least susceptible to infection by all tested pathogens were leaves from treatment I. Light spectrum composition is of practical importance for tomato seedling production. [ABSTRACT FROM AUTHOR]

Late blight (Phytophthora infestans), characterized by small water-soaked areas that rapidly enlarge to form purple-brown, oily appearing blotches, is the most destructive fungal disease that continues to stymie worldwide tomato production. Severe outbreaks have been recorded in tomato-growing areas throughout the world in recent years, and the vast majority of commercial tomato cultivars are extremely vulnerable to the late blight infection. The aim of this study was to screen the wild tomato Solanum habrochaites accessions LA1223, LA1353, LA1718, LA1777, LA2156, LA2167, and LA2556 under natural disease pressure conditions to find a possible source of resistance to late blight and also characterized these accessions for various morphological characters. Three S. habrochaites accessions (LA1777, LA2167, and LA2556) were resistant and superior to the susceptible check. With a PDI of 22.29, LA 1777 was shown to have the highest resistance, and as such, it may be used as a donor for late blight resistant tomato pre-breeding programmes in the near future. The success of high crossability (percentage) of some hybrid combinations using LA1777 as a male parent, such as LA3846 × LA1777 (77.77), LA2377 × LA1777 (62.50), and LA3317 × LA1777 (60.00), is encouraging for the development of pre-breeding genetic stocks as well as for the discovery of novel alleles in wild tomato populations. The morphological characterization of seven wild tomato accessions mainly confirms the guidelines of the International Plant Genetic Resources Institute. These accessions and their interspecific crosses showed wide variability in phenotypic and reproductive characters for plant height, flower color, exserted stigma, leaf margin, flowering time, fruit set, and other economic traits that will facilitate breeders in the development of superior tomato cultivars and F1 hybrids resistant to biotic stresses, as well as differentiate these S. habrochaites accessions for their potential use in genetic enhancement of cultivated tomatoes. [ABSTRACT FROM AUTHOR]

The Oomycetes fungi, known as water molds are a group of numerous hundred microorganisms that comprise certain of the most disturbing phytopathogens. They can cause damping-off, seedling blights, foliar blights, downy mildew and root rots. Tomato (Lycopersicon esculentum) is an economically and nutritionally important species grown worldwide. Late blight and damping off are two major diseases, which are caused by oomycetes. The present study collected infected samples of tomatoes from four geographic locations in Karnataka, India and identified the pathogens through morphological and molecular methods. Ten different fungal species were identified through microscopic study, with dominance of Pythium and Phytophthora species at all locations. Molecular characterization through ITS sequences and phylogenetic analysis confirmed the presence of two oomycetes Pythium aphanidermatum and Phytophthora infestans. ITS sequences of these two fungi were deposited at NCBI with accession numbers OR677915 and OR677916, respectively. Experimental inoculation of Pythium aphanidermatum (20ml Inoculum/litre) in soil having 20-day-old tomato plants resulted in the 100% yellowing, wilting, collapse, and death of plants within 7 days of inoculation. Inoculation of Phytophthora infestans (20ml Inoculum/litre) was sprayed on fruiting tomato plants resulting in black/brown lesions followed by up to 80% wilting of leaves and fruits within 7 days of spray. This research contributes to our understanding of fungal diseases affecting tomato crops in Karnataka, India and provides a foundation for future studies aimed at developing sustainable disease management practices. [ABSTRACT FROM AUTHOR]

In this investigation, we described the synthesis and characterization of Silica nanoparticles from oat grass leaves. Our study described the synthesis and characterization of Silica nanoparticles derived from oat grass leaves. We analysed the nanoparticles using different characterization techniques including Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy dispersive X-ray (EDX) analysis. Scanning electron micrographs and transmission electron micrographs revealed the formation agglomerated amorphous silica nanoparticles with an average size of 100nm. EDX analysis was utilized to discover the elemental composition of the silica nanoparticles. Under laboratory conditions, the direct antifungal activity of silica nanoparticles (SiO2-NPs) against Phytophthora infestans was assessed. A concentration of 1.4% SiO2-NPs demonstrates increased antifungal action against the pathogen. The study reveals encouraging findings regarding the use of SiO2-NPs as a viable and safe substitute for fungicides in controlling late blight diseases. [ABSTRACT FROM AUTHOR]

Plant pathogens manipulate the cellular environment of the host to facilitate infection and colonization that often lead to plant diseases. To accomplish this, many specialized pathogens secrete virulence proteins called effectors into the host cell, which subvert processes such as immune signaling, gene transcription, and host metabolism. Phytophthora infestans, the causative agent of potato late blight, employs an expanded repertoire of RxLR effectors with WY domains to manipulate the host through direct interaction with protein targets. However, our understanding of the molecular mechanisms underlying the interactions between WY effectors and their host targets remains limited. In this study, we performed a structural and biophysical characterization of the P. infestans WY effector Pi04314 in complex with the potato Protein Phosphatase 1-c (PP1c). We elucidate how Pi04314 uses a WY domain and a specialized C-terminal loop carrying a KVxF motif that interact with conserved surfaces on PP1c, known to be used by host regulatory proteins for guiding function. Through biophysical and in planta analyses, we demonstrate that Pi04314 WY or KVxF mutants lose their ability to bind PP1c. The loss of PP1c binding correlates with changes in PP1c nucleolar localization and a decrease in lesion size in plant infection assays. This study provides insights into the manipulation of plant hosts by pathogens, revealing how effectors exploit key regulatory interfaces in host proteins to modify their function and facilitate disease. [Graphic: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Late blight, caused by Phytophthora infestans, is one of the most serious diseases affecting potatoes (Solanum tuberosum L.). Long non-coding RNAs (lncRNAs) are transcripts with a length of more than 200 nucleotides that have no proteincoding potential. Few studies have been conducted on lncRNAs related to plant immune regulation in plants, and the molecular mechanisms involved in this regulation require further investigation. We identified and screened an lncRNA that specifically responds to P. infestans infection, namely, StlncRNA13558. P. infestans infection activates the abscisic acid (ABA) pathway, and ABA induces StlncRNA13558 to enhance potato resistance to P. infestans. StlncRNA13558 positively regulates the expression of its co-expressed PR-related gene StPRL. StPRL promotes the accumulation of reactive oxygen species and transmits a resistance response by affecting the salicylic acid hormone pathway, thereby enhancing potato resistance to P. infestans. In summary, we identified the potato late blight resistance lncRNA StlncRNA13558 and revealed its upstream and downstream regulatory relationship of StlncRNA13558. These results improve our understanding of plant-pathogen interactions' immune mechanism and elucidate the response mechanism of lncRNA-target genes regulating potato resistance to P. infestans infection. [ABSTRACT FROM AUTHOR]

Plant glycerate kinase (GK) was previously considered an exclusively chloroplastic enzyme of the glycolate pathway (photorespiration), and its sole predicted role was to return most of the glycolate-derived carbon (as glycerate) to the Calvin cycle. However, recent discovery of cytosolic GK revealed metabolic links for glycerate to other processes. Although GK was initially proposed as being solely regulated by substrate availability, subsequent discoveries of its redox regulation and the light involvement in the production of chloroplastic and cytosolic GK isoforms have indicated a more refined regulation of the pathways of glycerate conversion. Here, we re-evaluate the importance of GK and emphasize its multifaceted role in plants. Thus, GK can be a major player in several branches of primary metabolism, including the glycolate pathway, gluconeogenesis, glycolysis, and C4 metabolism. In addition, recently, the chloroplastic (but not cytosolic) GK isoform was implicated as part of a light-dependent plant immune response to pathogen attack. The origins of glycerate are also discussed here; it is produced in several cell compartments and undergoes huge fluctuations depending on light/dark conditions. The recent discovery of the vacuolar glycerate transporter adds yet another layer to our understanding of glycerate transport/metabolism and that of other two- and three-carbon metabolites. [ABSTRACT FROM AUTHOR]

Cytochrome P450s represent one of the largest protein families across all domains of life. In plants, biotic stress can regulate the expression of some P450 genes. However, the CYPome (cytochrome P450 complement) in Solanum tuberosum and its response to Phytophthora infestans infection remains unrevealed. In this study, 488 P450 genes were identified from potato genome, which can be divided into 41 families and 57 subfamilies. Responding to the infection of P. infestans , 375 potato P450 genes were expressed in late blight resistant or susceptible cultivars. A total of 14 P450 genes were identified as resistant related candidates, and 81 P450 genes were identified as late blight responsive candidates. Several phytohormone biosynthesis, brassinosteroid biosynthesis, and phenylpropanoid biosynthesis involved P450 genes were differentially expressed during the potato-pathogen interactions. This study firstly reported the CYPome in S. tuberosum , and characterized the expression patterns of these P450 genes during the infection of P. infestans. [ABSTRACT FROM AUTHOR]

This study explores the population dynamics of Phytophthora infestans in Estonia from 2005 to 2022, focusing on genetic diversity and potential shifts in reproductive strategies. In total, 153 P. infestans isolates were collected throughout Estonia over ten growing seasons. Genotyping revealed considerable genetic diversity, with most isolates not corresponding to known multilocus genotypes (MLGs). Still, instances of invasive clonal lineages were observed, notably EU_41_A2. The data indicate the likelihood of random mating rather than clonal reproduction in all the analyzed years. The principal coordinate analysis (PCoA) results revealed no distinct clustering among the sampling years. Statistical analysis and the minimum spanning network (MSN) indicated low genetic differentiation between years with minimal fluctuations in allele frequencies. The continuous monitoring of P. infestans populations is essential for detecting any changes from the current evolutionary trajectory and implement effective disease management strategies, especially considering the recent emergence of EU_41_A2 in the Nordics and the potential impacts of climate change. [ABSTRACT FROM AUTHOR]

Phosphites (Phi) are inorganic salts widely used to protect plants from pathogens, especially oomycetes, on a wide range of horticultural crops. They were studied at the molecular level in different pathosystems; however, their mode of action is not completely understood. In this work, we investigate the participation of polyamine (PA) metabolism in the defence mechanism induced by Phi. To this aim, potato plants were treated with potassium phosphite (KPhi), and 3 days later, leaves were inoculated with Phytophthora infestans (P. infestans). The content of free PAs was analysed and showed that KPhi induced the accumulation of spermine (Spm), spermidine (Spd) and putrescine (Put). However, when treated leaves were detached and inoculated with P. infestans, their accumulation was even higher. In addition, the expression of genes implicated in PA synthesis and degradation was measured. Most of the genes involved in PA biosynthesis showed no changes in their expression upon KPhi treatment, except for those involved in Spm synthesis: Spm synthase and S-adenosyl-L-methionine decarboxylase (SPMS and SAMDC, respectively). On the other hand, the catabolism genes: diamine oxidase (DAO), and polyamine oxidases PAO1, PAO2 and PAO5, but not PAO4, decreased their expression after inoculation with P. infestans, and this was reverted by KPhi pretreatment. To investigate this effect, assays were carried out using a PA oxidase inhibitor showing that defence responses induced by KPhi do not require products of PA catabolism. Additionally, we analysed in silico phytohormone and stress-responsive cis-elements in PAO gene promoters, which might explain, at least in part, the different behaviour of PAO4. [ABSTRACT FROM AUTHOR]

Foliar diseases are the significant production constraints in tomatoes. Among them, foliar fungal diseases in tomatoes, such as early blight (Alternaria linaria), Septoria leaf spot (Septoria lycopersici), and late blight (Phytophthora infestans), which is oomycetes, have higher economic significance. This paper will discuss the etiology, host range, distribution, symptoms, and disease cycle to help us understand the biology, followed by management approaches emphasizing the resistance breeding approach for these diseases. We provide an analytical review of crop improvement efforts, including conventional and molecular methods for improving these diseases' resistance. We discuss the importance of modern breeding tools, including genomics, genetic transformation, and genome editing, to improve the resistance to these diseases in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: Phytophthora capsici is an extremely destructive phytopathogenic oomycete that causes huge economic losses. However, due to the drug resistance risk and environmental threat of chemical fungicides, it is necessary to develop environmentally friendly biocontrol alternatives. Rhein is a major medicinal ingredient of traditional Chinese herbs, and it is widely used in the medical field. However, its inhibitory effect against phytopathogens is unknown. Herein, the antifungal spectrum of rhein and its possible action mechanism against P. capsici were investigated. RESULTS: Rhein possessed broad‐spectrum antifungal activity against phytopathogens, particularly P. capsici, Phytophthora infestans, Helminthosporium maydis, and Rhizoctonia solani. Rhein inhibited the mycelial growth as well as the spore germination of P. capsici with mean 50% effective concentration (EC50) values of 4.68 μg mL−1 and 6.57 μg mL−1 against 117 P. capsici isolates, respectively. Rhein effectively suppressed the occurrence and spread of Phytophthora blight and significantly destroyed the cell membrane permeability and integrity of P. capsici, corroded its cell wall integrity, and damaged its morphology and ultrastructure. Moreover, rhein caused a considerable reduction in the phospholipid and cellulose contents. Genome‐wide transcriptional profiling of P. capsici in response to rhein indicated significant reduction in the expression levels of genes participating in glycerolipid metabolism and starch and sucrose metabolism. Additionally, rhein strengthened the disease defense system of pepper by enhancing related enzyme activities. CONCLUSION: This study demonstrated that rhein could effectively inhibit P. capsici using multiple mechanisms of action. Rhein has the potential to be an efficient alternative to control diseases caused by P. capsici. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]