Search Results (95)

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. Full article

Cultivated potato (Solanum tuberosum) is a major crop worldwide. It occupies the second place after cereals (corn, rice, and wheat). This important crop is threatened by the Oomycete Phytophthora infestans, the agent of late blight disease. This pathogen was first encountered during the Irish famine during the 1840s and is a reemerging threat to potatoes. It is mainly controlled chemically by using fungicides, but due to health and environmental concerns, the best alternative is resistance. When there is no disease, no treatment is required. In this study, we present a summary of the ongoing efforts concerning resistance breeding of potato against this devastating pathogen, P. infestans. This work begins with the search for and selection of resistance genes, whether they are from within or from outside the species. The genetic methods developed to date for gene mining, such as effectoromics and GWAS, provide researchers with the ability to identify genes of interest more efficiently. Once identified, these genes are cloned using molecular markers (MAS or QRL) and can then be introduced into different cultivars using somatic hybridization or recombinant DNA technology. More innovative technologies have been developed lately, such as gene editing using the CRISPR system or gene silencing, by exploiting iRNA strategies that have emerged as promising tools for managing Phytophthora infestans, which can be employed. Also, gene pyramiding or gene stacking, which involves the accumulation of two or more R genes on the same individual plant, is an innovative method that has yielded many promising results. All these advances related to the development of molecular techniques for obtaining new potato cultivars resistant to P. infestans can contribute not only to reducing losses in agriculture but especially to ensuring food security and safety. Full article

Starch degradation provides energy and signaling molecules for plant growth, development, defense, and stress response. α-amylase (AMY) is one of the most important enzymes in this process. Potato tubers are rich in starch, and the hydrolysis of starch into sugar negatively impacts the frying quality of potato. Despite its importance, the AMY gene family has not been fully explored in potatoes. Here, we performed a detailed analysis of the StAMY gene family to determine its role in potato. Twenty StAMY genes were identified across the potato genome and were divided into three subgroups. The promoters of StAMY genes contained an array of cis-acting elements involved in growth and development, phytohormone signaling, and stress and defense responses. StAMY8, StAMY9, StAMY12, and StAMY20 were specifically expressed in mature tubers. Different StAMY gene family members tended to be upregulated in response to β-aminobutyric acid (BABA), Phytophthora infestans (P. infestans), benzothiadiazole (BTH), heat, salt, and drought stress. In addition, different StAMY gene family members tended to be responsive to abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA3), and 6-benzylaminopurine (BAP) treatment. These results suggest that StAMY gene family members may be involved in starch and sugar metabolism, defense, stress response, and phytohormone signaling. The results of this study may be applicable to other starchy crops and lay a foundation for further research on the functions and regulatory mechanisms of AMY genes. Full article

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. Full article

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. Full article

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. Full article

The growing imperative for sustainable development generates research in the field and explores innovative approaches to manage vegetable crops to reduce the usage of synthetic inputs commonly associated with conventional practices as well as to promote the undertaking of organic solutions. Tomatoes are universally recognized as a highly significant and popular fruit vegetable due to their large use palette. Trials were carried out in the Gâlgău area, Transylvania, Romania. Bifactorial experiments were organized to quantify the influence of fertilization and treatments on the morpho-productive and quantitative traits of the Ruxandra tomato cultivar and on Phytophthora infestans levels of infection. The use of mixed fertilization resulted in the best performances of morphological traits (highest leaf area, highest number of leaves and fruits, highest chlorophyll content) and part of the productive traits (highest content of dry matter), and the lowest levels of infection in cv. Ruxandra, while the use of NPK soil fertilization led to the best performances in fruit weight and NUE, whatever the administered treatment. The treatment with herbal extracts showed a similar efficacy in increasing the averages of morpho-productive traits and diminishing the P. infestans level of infection compared with the conventional treatment. The treatment efficacy was mainly influenced by temperature and relative air humidity, regardless of the fertilization strategies applied. Full article

Late blight is a destructive disease of solanaceous crops such as tomato (Solanum lycopersicum L.), caused by the Oomycete Phytophthora infestans (Mont.) de Bary. Late blight is generally controlled by fungicide applications, which quickly become ineffective due to the appearance of new P. infestans genotypes that can overcome the resistance of improved tomato cultivars and cause total production losses. The aim of this study is to assess the resistance level of tomato cultivars under controlled conditions and inoculations were carried out on detached leaflets (cvs. Trakia, Saint Pierre and Marmande) using inoculums of the major P. infestans clonal lineages found in Algeria such as EU_13_A2 (n = 1), EU_23_A1 (n = 2) and EU_2_A1 (n = 1) (three replicates of each isolate). This investigation showed that the choice of resistant cultivars can help control late blight and provide economic and environmental advantages by reducing the use of inputs. Full article

Phytophthora infestans, an Oomycete pathogen, has a devastating impact on potato agriculture, leading to the extensive use of chemical fungicides to prevent its outbreaks. Spraying double-stranded RNAs to suppress specific genes of the pathogen via the RNA interference (RNAi) pathway may provide an environmentally friendly alternative to chemicals. However, this novel approach will require various target genes and application strategies to be tested. Using the L4440 backbone, we have designed two plasmids to express dsRNA targeting inf1 and inf4 genes of P. infestans that are known to contribute to the disease development at different stages. The dsRNA produced by the bacteria was tested on potato explants and demonstrated a statistically significant reduction in lesions five days after inoculation compared to water treatment. The study results allow us to consider our approach to be promising for potato late blight control. Full article

Late blight, caused by the oomycete Phytophthora infestans, is one of the most important diseases affecting tomato and potato production worldwide. In Thailand, the disease is widespread in the north and northeast, especially in the Chiang-Mai and Tak provinces. The mating type, metalaxyl sensitivity, mitochondrial DNA (mtDNA) haplotype, RG57 fingerprinting, and microsatellite were used to characterize the P. infestans populations. The study revealed that the P. infestans of tomato isolates in Thailand are of the same lineage as those from 1994 until 2002. The clonal lineages that were found in the potato populations have changed since 1994. The changes in P. infestans isolates in the potato populations have likely been the result of the import of seed potatoes to Thailand. Furthermore, the P. infestans populations in potatoes show resistance to metalaxyl, whereas those from tomato isolates show sensitivity to fungicides. The reasons for the different responses can be attributed to (i) the use of metalaxyl, (ii) the host preferences of P. infestans, and (iii) the migration of new genotypes from infected potato seeds. Full article

Potato late blight disease is caused by the oomycete Phytophthora infestans and is listed as one of the most severe phytopathologies on Earth. The current environmental issues require new methods of pest management. For that reason, plant secondary metabolites and, in particular, essential oils (EOs) have demonstrated promising potential as pesticide alternatives. This review presents the up-to-date work accomplished using EOs against P. infestans at various experimental scales, from in vitro to in vivo. Additionally, some cellular mechanisms of action on Phytophthora spp., especially towards cell membranes, are also presented for a better understanding of anti-oomycete activities. Finally, some challenges and constraints encountered for the development of EOs-based biopesticides are highlighted. Full article

Mancozeb (MZ) is a broadly used fungicide for the control of plant diseases, including late blight in potatoes caused by the oomycete Phytophthora infestans (Mont.) De Bary. MZ has been banned for agricultural use by the European Union as of January 2022 due to its hazards to humans and the environment. In a search for replacement fungicides, twenty-seven registered anti-oomycete fungicidal preparations were evaluated for their ability to mitigate the threat of this disease. Fourteen fungicides provided good control (≥75%) of late blight in potted potato and tomato plants in growth chambers. However, in Tunnel Experiment 1, only three fungicides provided effective control of P. infestans in potatoes: Cyazofamid (Ranman, a QiI inhibitor), Mandipropamid (Revus, a CAA inhibitor), and Oxathiapiprolin + Benthiavalicarb (Zorvek Endavia, an OSBP inhibitor + CAA inhibitor). In Tunnel Experiment 2, these three fungicides were applied at the recommended doses at 7-, 9-, and 21-day intervals, respectively, totaling 6, 4, and 2 sprays during the season. At 39 days post-inoculation (dpi), control efficacy increased in the following order: Zorvec Endavia > Ranman > Revus > Mancozeb. Two sprays of Zorvec Endavia were significantly more effective in controlling the blight than six sprays of Ranman or four sprays of Revus. We, therefore, recommend using these three fungicides as replacements for mancozeb for the control of late blight in potatoes. A spray program that alternates between these three fungicides may be effective in controlling the disease and also in avoiding the build-up of resistance in P. infestans to mandipropamid and oxathiapiprolin. Full article

Plants are prone to be attacked by various pathogenic microorganisms, leading to significant crop yield losses. Pesticides are used to control agricultural pathogens; however, frequently, they are toxic synthetic products. This work evaluated the antibacterial and antifungal activity of Pernettya prostrata, and Rubus roseus plant extracts against three phytopathogens Ralstonia solanacearum, Phytophthora infestans, and Neopestalotiopsis javaensis responsible for causing banana bacterial wilt, late blight y scab diseases, respectively. The extracts were obtained in methanol. The phytopathogens were isolated from diseased plants grown in Ecuador, R. solanacearum was isolated from samples of Musa paradiasiaca, P. infestans from samples of Solanum lycopersicum and N. javaensis from diseased samples of Persea americana—morphological and molecular methods identified the isolated pathogens. The antibacterial activity was determined by the microtiter broth dilution method; six serial concentrations of the extracts were tested. The antifungal activity was determined based on the effects of the plant extracts on the inhibition of radial growth of fungi; five serial concentrations of the extracts were tested. The extracts of P. prostrata and R. roseus showed activity against R. solanacearum and P. infestans with a MIC of 22.5 and 31.25 mg/mL, respectively. Full article

Sugar Efflux transporters (SWEET) are involved in diverse biological processes of plants. Pathogens have exploited them for nutritional gain and subsequently promote disease progression. Recent studies have implied the involvement of potato SWEET genes in the most devastating late blight disease caused by Phytophthora infestans. Here, we identified and designated 37 putative SWEET genes as StSWEET in potato. We performed detailed in silico analysis, including gene structure, conserved domains, and phylogenetic relationship. Publicly available RNA-seq data was harnessed to retrieve the expression profiles of SWEET genes. The late blight-responsive SWEET genes were identified from the RNA-seq data and then validated using quantitative real-time PCR. The SWEET gene expression was studied along with the biotrophic (SNE1) and necrotrophic (PiNPP1) marker genes of P. infestans. Furthermore, we explored the co-localization of P. infestans resistance loci and SWEET genes. The results indicated that nine transporter genes were responsive to the P. infestans in potato. Among these, six transporters, namely StSWEET10, 12, 18, 27, 29, and 31, showed increased expression after P. infestans inoculation. Interestingly, the observed expression levels aligned with the life cycle of P. infestans, wherein expression of these genes remained upregulated during the biotrophic phase and decreased later on. In contrast, StSWEET13, 14, and 32 didn’t show upregulation in inoculated samples suggesting non-targeting by pathogens. This study underscores these transporters as prime P. infestans targets in potato late blight, pivotal in disease progression, and potential candidates for engineering blight-resistant potato genotypes. Full article

Potato (Solanum tuberosum) is a valuable staple crop that provides nutrition for a large part of the human population around the world. However, the domestication process reduced its resistance to pests and pathogens. Phytophthora infestans, the causal agent of late blight disease, is the most destructive pathogen of potato plants. Considerable efforts have been made to develop late blight-resistant potato cultivars, but the success has been limited and present-day potato production requires the extensive use of fungicides. In this review, we summarize known sources of late blight resistance and obstacles in P. infestans control. We outline the problematic aspects of chemical treatment, the possible use of biological control, and available resources of natural resistance in wild Solanum accessions. We focus on prospective putative markers of resistance that are often overlooked in genome-centered studies, including secondary metabolites from alkaloid, phenylpropanoid, and terpenoid classes, lipids, proteins, and peptides. We discuss the suitability of these molecules for marker-assisted selection and the possibility of increasing the speed of conventional breeding of more resilient cultivars. Full article