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Precise and automatic plant disease detection represent a fundamental research topic. Indeed, traditional or manual disease detection can be laborious, inaccurate and time-consuming. In this work, a particular attention is given to automatic potato late blight disease detection. In fact, this devastating pathogen leads every year to a significant reduction in potato yields. In addition, since potatoes are a major food source for many nations, decreased production generate a real food insecurity. Therefore, considering these challenges, using advanced techniques in computer vision and machine learning allowed farmers to swiftly and accurately identify disease. The main objective of this research work is to generate a super-resolved labeled dataset (SRD) and evaluate its impact on plant disease detection. Three states of the art object detection methods (Faster-RCNN, Detr and Yolo V8) have been used to conduct an exhaustive evaluation on the effect of using a super-resolved dataset to perform detection. The obtained results show that the detection of potato late blight disease is enhanced using SRD. Training Yolo V8 model on SRD outperform other trained models in detecting very small lesions. In fact, training Yolo V8 on SRD reached higher mAP, lower Loss values and a reasonable inference time, making it suitable for real time applications. [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]

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]

Summary: Ubiquitin‐like domain‐containing proteins (UDPs) are involved in the ubiquitin‐proteasome system because of their ability to interact with the 26S proteasome. Here, we identified potato StUDP as a target of the Phytophthora infestans RXLR effector Pi06432 (PITG_06432), which supresses the salicylic acid (SA)‐related immune pathway.By overexpressing and silencing of StUDP in potato, we show that StUDP negatively regulates plant immunity against P. infestans. StUDP interacts with, and destabilizes, the 26S proteasome subunit that is referred to as REGULATORY PARTICLE TRIPLE‐A ATP‐ASE (RPT) subunit StRPT3b. This destabilization represses the proteasome activity. Proteomic analysis and Western blotting show that StUDP decreases the stability of the master transcription factor SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) in SA biosynthesis.StUDP negatively regulates the SA signalling pathway by repressing the proteasome activity and destabilizing StSARD1, leading to a decreased expression of the SARD1‐targeted gene ISOCHORISMATE SYNTHASE 1 and thereby a decrease in SA content. Pi06432 stabilizes StUDP, and it depends on StUDP to destabilize StRPT3b and thereby supress the proteasome activity.Our study reveals that the P. infestans effector Pi06432 targets StUDP to hamper the homeostasis of the proteasome by the degradation of the proteasome subunit StRPT3b and thereby suppresses SA‐related immunity. [ABSTRACT FROM AUTHOR]

Late blight caused by the oomycete Phytophthora infestans is considered to be one of the most severe diseases of potato and tomato worldwide. Whilst current synthetic fungicides are efficient at controlling this disease, they are an environmental and economic burden. In line with EU directives to reduce the use of synthetic pesticides and increase the use of sustainable alternative disease control strategies that can form part of integrated pest management systems, practical biological control solutions are urgently needed. Despite the fact that there has been a large body of scientific research into microorganisms with potential for the biological control of late blight disease, relatively few commercial biocontrol agents, licensed to control late blight, exist. Furthermore, the practical uptake of those in Europe is lower than might be expected, suggesting that such solutions are not yet feasible, or effective. Here we review the scientific literature, focusing on the most recent developments in the hunt for efficient and sustainable biological control of late blight disease. We discuss the progress in our mechanistic understanding of mycoparasite–prey interactions, in the context of late blight and the challenges and limitations to the use of such knowledge in practical disease control within a European context. • Over 96 peer-reviewed papers on late blight biocontrol in the last 20 years. • The challenge is to move away from pure in vitro studies to in agro applications. • We need an IPM systems approach to biocontrol of late blight. • We must incorporate pathogen and BCA evolutionary ecological knowledge into IPM. • BCAs could be bioengineered as "cell factories" to produce late blight biopesticides. [ABSTRACT FROM AUTHOR]

Grafting has been widely used to defense soil borne diseases and nematodes in vegetables production. However, the underlying mechanism of grafting-improved disease resistance is largely unknown. In this study, grafting cv. 'Ledu' scion to cv. 'Jhigxin No. 5' rootstocks improved the resistance of pepper to Phytophthora capsici. To gain insights into the regulatory networks related to grafting, we performed transcriptome analysis of grafting and control pepper plants with or without P. capsici inoculation. RNA-seq analysis revealed that P. capsici infection largely re-programmed the pepper transcriptome and differentially expressed genes (DEGs) functionally annotated to metabolism processes including photosynthesis, response to stimulus, enzyme activity, and transcription were significantly enriched. Furthermore, the expression levels of most DEGs induced by P. capsici infection, such as genes functionally related to plant hormone signal transduction, plantpathogen interaction, photosynthesis, reactive oxygen species, tend to recover to the control levels in grafting pepper plants, which help pepper maintain moderate plant defense response and considerable accumulation level of assimilation product, therefore fine-turning the dynamic balance between pepper growth-defense tradeoffs. Taken together, our results suggest the dynamic transcriptional programming in grafting pepper that underpin P. capsici disease and providing insight that the fine-tuning balance between growth and defense of grafting pepper. [ABSTRACT FROM AUTHOR]

Abstract Background Late blight disease (LBD) caused by the pathogen Phytophthora infestans (PI), is the most devastating disease limiting potato (Solanum tuberosum) production globally. Currently, this disease pathogen is re-emerging and appearing in new areas at a very high intensity. A better understanding of the natural defense mechanisms against PI in different potato cultivars especially at the protein level is still lacking. Therefore, to elucidate potato proteome response to PI, we investigated changes in the proteome and leaf morphology of three potato cultivars, namely; Favorita (FA), Mira (MA), and E-malingshu N0.14 (E14) infected with PI by using the iTRAQ-based quantitative proteomics analysis. Results A total of 3306 proteins were found in the three potato genotypes, and 2044 proteins were quantified. Cluster analysis revealed MA and E14 clustered together separately from FA. The protein profile and related functions revealed that the cultivars shared a typical hypersensitive response to PI, including induction of elicitors, oxidative burst, and suppression of photosynthesis in the potato leaves. Meanwhile, MA and E14 deployed additional specific response mechanism different from FA, involving high induction of protease inhibitors, serine/threonine kinases, terpenoid, hormone signaling, and transport, which contributed to MA tolerance of LBD. Furthermore, inductions of pathogenesis-related proteins, LRR receptor-like kinases, mitogen-activated protein kinase, WRKY transcription factors, jasmonic acid, and phenolic compounds mediate E14 resistance against LBD. These proteins were confirmed at the transcription level by a quantitative polymerase chain reaction and at the translation level by western-blot. Conclusions We found several proteins that were differentially abundant among the cultivars, that includes common and cultivar specific proteins which highlighted similarities and significant differences between FA, MA, and E14 in terms of their defense response to PI. Here the specific accumulation of mitogen-activated protein kinase, Serine/threonine kinases, WRKY transcription played a positive role in E14 immunity against PI. The candidate proteins identified reported in this study will form the basis of future studies and may improve our understanding of the molecular mechanisms of late blight disease resistance in potato.

In this study defense responses in three potato varieties with different levels of reaction to the late blight disease caused by Phytophthora infestans were analyzed after inoculation with the pathogen. In the resistant cv. Pastusa Suprema, increased intensity of H2O2 and callose deposit accumulation was observed beginning at 24 hours after inoculation, followed by a hypersensitive response at the inoculation points. In the moderately resistant cv. Diacol-Monserrate, the same responses were observed as in the resistant variety, but with less intensity over time. For the susceptible cv. Diacol-Capiro, the responses observed occurred later than in the other two varieties, subsequent to the advance of the pathogen over extensive necrotic areas. These results suggest that early, intense peroxide and callose accumulation and a hypersensitive response are associated with the observed resistance of the cv. Pastusa Suprema and cv. Diacol-Monserrate to P. infestans.

Previously, a Phytophthora infestans resistance QTL from Solanum habrochaites chromosome 11 was introgressed into cultivated tomato (S. lycopersicum). Fine mapping of this resistance QTL using near-isogenic lines (NILs) revealed some co-located QTL with undesirable effects on plant size, canopy density, and fruit size traits. Subsequently, higher-resolution mapping with sub-NILs detected multiple P. infestans resistance QTL within this 9.4-cM region of chromosome 11. In our present study, these same sub-NILs were also evaluated for 17 horticultural traits, including yield, maturity, fruit size and shape, fruit quality, and plant architecture traits in replicated field experiments over 2 years. The horticultural trait QTL originally detected by fine mapping each fractionated into two or more QTL at higher resolution. A total of 34 QTL were detected across all traits, with 14% exhibiting significant QTL × environment interactions (QTL × E). QTL for many traits were co-located, suggesting either pleiotropic effects or tight linkage among genes controlling these traits. Recombination in the pericentromeric region of the introgression between markers TG147 and At4g10050 was suppressed to approximately 29.7 Mbp per cM, relative to the genomewide average of 750 kbp per cM. The genetic architecture of many of the horticultural and P. infestans resistance traits that mapped within this chromosome 11 S. habrochaites region is complex. Complicating factors included fractionation of QTL, pleiotropy or tight linkage of QTL for multiple traits, pericentromeric chromosomal location(s), and/or QTL × E. High-resolution mapping of QTL in this region would be needed to determine which specific target QTL could be useful in breeding cultivated tomato.

Previously, a Phytophthora infestans resistance QTL from Solanum habrochaites chromosome 11 was introgressed into cultivated tomato (S. lycopersicum). Fine mapping of this resistance QTL using near-isogenic lines (NILs) revealed some co-located QTL with undesirable effects on plant size, canopy density, and fruit size traits. Subsequently, higher-resolution mapping with sub-NILs detected multiple P. infestans resistance QTL within this 9.4-cM region of chromosome 11. In our present study, these same sub-NILs were also evaluated for 17 horticultural traits, including yield, maturity, fruit size and shape, fruit quality, and plant architecture traits in replicated field experiments over 2 years. The horticultural trait QTL originally detected by fine mapping each fractionated into two or more QTL at higher resolution. A total of 34 QTL were detected across all traits, with 14% exhibiting significant QTL × environment interactions (QTL × E). QTL for many traits were co-located, suggesting either pleiotropic effects or tight linkage among genes controlling these traits. Recombination in the pericentromeric region of the introgression between markers TG147 and At4g10050 was suppressed to approximately 29.7 Mbp per cM, relative to the genomewide average of 750 kbp per cM. The genetic architecture of many of the horticultural and P. infestans resistance traits that mapped within this chromosome 11 S. habrochaites region is complex. Complicating factors included fractionation of QTL, pleiotropy or tight linkage of QTL for multiple traits, pericentromeric chromosomal location(s), and/or QTL × E. High-resolution mapping of QTL in this region would be needed to determine which specific target QTL could be useful in breeding cultivated tomato.

Phytophthora infestans is a destructive pathogen of potato and a model for investigations of oomycete biology. The successful application of a CRISPR gene editing system to P. infestans is so far unreported. We discovered that it is difficult to express CRISPR/Cas9 but not a catalytically inactive form in transformants, suggesting that the active nuclease is toxic. We were able to achieve editing with CRISPR/Cas12a using vectors in which the nuclease and its guide RNA were expressed from a single transcript. Using the elicitor gene Inf1 as a target, we observed editing of one or both alleles in up to 13% of transformants. Editing was more efficient when guide RNA processing relied on the Cas12a direct repeat instead of ribozyme sequences. INF1 protein was not made when both alleles were edited in the same transformant, but surprisingly also when only one allele was altered. We discovered that the isolate used for editing, 1306, exhibited monoallelic expression of Inf1 due to insertion of a copia‐like element in the promoter of one allele. The element exhibits features of active retrotransposons, including a target site duplication, long terminal repeats, and an intact polyprotein reading frame. Editing occurred more often on the transcribed allele, presumably due to differences in chromatin structure. The Cas12a system not only provides a tool for modifying genes in P. infestans, but also for other members of the genus by expanding the number of editable sites. Our work also highlights a natural mechanism that remodels oomycete genomes. [ABSTRACT FROM AUTHOR]

Regardless of variable environmental conditions and changing pathogen populations, the Estonian potato cultivar (cv.) Ando has shown elevated field resistance to Phytophthora infestans for over 40 years. One of cv. Ando’s parents, the Latvian cultivar Agra, is considered a cultivar of medium to low resistance, the other parent, line 382-48, has a well-known source of resistance, Solanum demissum, in its pedigree. Segregation of late blight disease severity in a population of 95 hybrid plants from cv. Ando’s backcross to cv. Agra (cv. Ando x cv. Agra BC1) in field trials of three consecutive years (2013−2015) and in a test of a single pathogen isolate fits a model of additive action of multiple unlinked race-specific resistance genes responsible for the field resistance of cv. Ando. At least some of the resistance genes in cv. Ando’s genome do not function in juvenile plants and are developmentally upregulated.

Background: Late blight disease (LBD) caused by the pathogen Phytophthora infestans (PI), is the most devastating disease limiting potato (Solanum tuberosum) production globally. Currently, this disease pathogen is re-emerging and appearing in new areas at a very high intensity. A better understanding of the natural defense mechanisms against PI in different potato cultivars especially at the protein level is still lacking. Therefore, to elucidate potato proteome response to PI, we investigated changes in the proteome and leaf morphology of three potato cultivars, namely; Favorita (FA), Mira (MA), and E-malingshu N0.14 (E14) infected with PI by using the iTRAQ-based quantitative proteomics analysis. Results: A total of 3306 proteins were found in the three potato genotypes, and 2044 proteins were quantified. Cluster analysis revealed MA and E14 clustered together separately from FA. The protein profile and related functions revealed that the cultivars shared a typical hypersensitive response to PI, including induction of elicitors, oxidative burst, and suppression of photosynthesis in the potato leaves. Meanwhile, MA and E14 deployed additional specific response mechanism different from FA, involving high induction of protease inhibitors, serine/threonine kinases, terpenoid, hormone signaling, and transport, which contributed to MA tolerance of LBD. Furthermore, inductions of pathogenesis-related proteins, LRR receptor-like kinases, mitogen-activated protein kinase, WRKY transcription factors, jasmonic acid, and phenolic compounds mediate E14 resistance against LBD. These proteins were confirmed at the transcription level by a quantitative polymerase chain reaction and at the translation level by western-blot. Conclusions: We found several proteins that were differentially abundant among the cultivars, that includes common and cultivar specific proteins which highlighted similarities and significant differences between FA, MA, and E14 in terms of their defense response to PI. Here the specific accumulation of mitogen-activated protein kinase, Serine/threonine kinases, WRKY transcription played a positive role in E14 immunity against PI. The candidate proteins identified reported in this study will form the basis of future studies and may improve our understanding of the molecular mechanisms of late blight disease resistance in potato. [ABSTRACT FROM AUTHOR]

Late blight, caused by Phytophthora infestans, is the most devastating potato disease worldwide and results in catastrophic production losses. Reactive oxygen species (ROS) are signal molecules utilized at the early stage of plant immunity. Specifically, anionic peroxidases are reported to be involved in many plants' defense systems. However, there is limited information about the function of anionic peroxidase genes in potato immunity. Here, we report that StPOPA, a gene encoding a suberization-associated anionic peroxidase, was induced by P. infestans infection, mechanical damage, as well as jasmonic acid and ethylene treatments. Overexpression of StPOPA gene in potato enhanced potato resistance against P. infestans by promoting the accumulation of callose in the cell wall and ROS in the cytoplasm, and then the callose and ROS restricted the infection and spreading of the disease possibly by purposeful programmed cell death. Our results suggest that StPOPA plays a positive role in potato resistance to immunochallenge, and this gene could be used for the genetic improvement of resistance against potato late blight. [ABSTRACT FROM AUTHOR]

Transgenic potato event Vic.172, expressing three naturally occurring resistance genes (R genes) conferring complete protection against late blight disease, was evaluated for resistance to late blight, phenotypic characterization, and agronomic performance in field conditions at three locations during three seasons in Uganda. These trials were conducted by comparison to the variety Victoria from which Vic.172 derives, using identical fungicide treatment, except when evaluating disease resistance. During all seasons, the transgenic event Vic.172 was confirmed to have complete resistance to late blight disease, whereas Victoria plants were completely dead by 60–80 days after planting. Tubers from Vic.172 were completely resistant to LB after artificial inoculation. The phenotypic characterization included observations of the characteristics and development of the stems, leaves, flowers, and tubers. Differences in phenotypic parameters between Vic.172 and Victoria were not statistically significant across locations and seasons. The agronomic performance observations covered sprouting, emergence, vigor, foliage growth, and yield. Differences in agronomic performance were not statistically significant except for marketable yield in one location under high productivity conditions. However, yield variation across locations and seasons was not statistically significant, but was influenced by the environment. Hence, the results of the comparative assessment of the phenotype and agronomic performance revealed that transgenic event Vic.172 did not present biologically significant differences in comparison to the variety Victoria it derives from.

Regardless of variable environmental conditions and changing pathogen populations, the Estonian potato cultivar (cv.) Ando has shown elevated field resistance to Phytophthora infestans for over 40 years. One of cv. Ando's parents, the Latvian cultivar Agra, is considered a cultivar of medium to low resistance, the other parent, line 382-48, has a well-known source of resistance, Solanum demissum, in its pedigree. Segregation of late blight disease severity in a population of 95 hybrid plants from cv. Ando's backcross to cv. Agra (cv. Ando x cv. Agra BC1) in field trials of three consecutive years (2013−2015) and in a test of a single pathogen isolate fits a model of additive action of multiple unlinked race-specific resistance genes responsible for the field resistance of cv. Ando. At least some of the resistance genes in cv. Ando's genome do not function in juvenile plants and are developmentally upregulated. [ABSTRACT FROM AUTHOR]

In this study defense responses in three potato varieties with different levels of reaction to the late blight disease caused by Phytophthora infestans were analyzed after inoculation with the pathogen. In the resistant cv. Pastusa Suprema, increased intensity of H2O2 and callose deposit accumulation was observed beginning at 24 hours after inoculation, followed by a hypersensitive response at the inoculation points. In the moderately resistant cv. Diacol-Monserrate, the same responses were observed as in the resistant variety, but with less intensity over time. For the susceptible cv. Diacol-Capiro, the responses observed occurred later than in the other two varieties, subsequent to the advance of the pathogen over extensive necrotic areas. These results suggest that early, intense peroxide and callose accumulation and a hypersensitive response are associated with the observed resistance of the cv. Pastusa Suprema and cv. Diacol-Monserrate to P. infestans. [ABSTRACT FROM AUTHOR]

Late blight caused by the oomycete pathogen Phytophthora infestans is one of the most destructive diseases in potato cultivation. To successfully colonize its host, P. infestans secretes a suite of effector proteins that undermine plant immunity, many of which contain a conserved N-terminal RXLR motif that strongly resembles the host targeting motif in effectors of the malaria parasite Plasmodium falciparum. In this study, we focus on three P. infestans clade 5 aspartic proteases (PiAPs) that are homologous to Plasmepsin V (PMV), a Pl. falciparum AP responsible for cleaving effectors prior to translocation into red blood cells. Malaria parasites expressing mutated PMV are impaired in effector translocation and are less virulent. To determine whether clade 5 PiAPs play similar roles in virulence, we characterized P. infestans transformants with either reduced or enhanced PiAP expression levels. Phytophthora infestans transformants with altered PiAP10 or PiAP12 expression were found to be impaired in mycelial growth and sporangia production, and are hampered in their virulence on potato leaves. This was not observed in PiAP11 transformants. Activity assays showed that PiAP10 and PiAP12 possess moderate protease activity, and can potentially cleave the RXLR effector PiAVR4, but not a PiAVR4 version with a mutated RXLR motif. These findings imply that P. infestans APs function in the proteolytic cleavage of RXLR effectors, and warrant further investigation to verify and confirm the role of clade 5 PiAPs in effector processing. [ABSTRACT FROM AUTHOR]

Summary: The successful invasion of host tissue by (hemi‐)biotrophic plant pathogens is dependent on modifications of the host plasma membrane to facilitate the two‐way transfer of proteins and other compounds. Haustorium formation and the establishment of extrahaustorial membranes are probably dependent on a variety of enzymes that modify membranes in a coordinated fashion. Phospholipases, enzymes that hydrolyse phospholipids, have been implicated as virulence factors in several pathogens. The oomycete Phytophthora infestans is a hemibiotrophic pathogen that causes potato late blight. It possesses different classes of phospholipase D (PLD) proteins, including small PLD‐like proteins with and without signal peptide (sPLD‐likes and PLD‐likes, respectively). Here, we studied the role of sPLD‐like‐1, sPLD‐like‐12 and PLD‐like‐1 in the infection process. They are expressed in expanding lesions on potato leaves and during in vitro growth, with the highest transcript levels in germinating cysts. When expressed in planta in the presence of the silencing suppressor P19, all three elicited a local cell death response that was visible at the microscopic level as autofluorescence and strongly boosted in the presence of calcium. Moreover, inoculation of leaves expressing the small PLD‐like genes resulted in increased lesion growth and greater numbers of sporangia, but this was abolished when mutated PLD‐like genes were expressed with non‐functional PLD catalytic motifs. These results show that the three small PLD‐likes are catalytically active and suggest that their enzymatic activity is required for the promotion of virulence, possibly by executing membrane modifications to support the growth of P. infestans in the host. [ABSTRACT FROM AUTHOR]

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Heavy metal pollution causes many soils to become a toxic environment not only for plants, but also microorganisms; however, little is known how heavy metal contaminated environment affects metabolism of phytopathogens and their capability of infecting host plants. In this study the oomycete Phytophthora infestans (Mont.) de Bary, the most harmful pathogen of potato, growing under moderate cadmium stress (Cd, 5 mg/L) showed nitro-oxidative imbalance associated with an enhanced antioxidant response. Cadmium notably elevated the level of nitric oxide, superoxide and peroxynitrite that stimulated nitrative modifications within the RNA and DNA pools in the phytopathogen structures. In contrast, the protein pool undergoing nitration was diminished confirming that protein tyrosine nitration is a flexible element of the oomycete adaptive strategy to heavy metal stress. Finally, to verify whether Cd is able to modify P. infestans pathogenicity, a disease index and molecular assessment of disease progress were analysed indicating that Cd stress enhanced aggressiveness of vr P. infestans towards various potato cultivars. Taken together, Cd not only affected hyphal growth rate and caused biochemical changes in P. infestans structures, but accelerated the pathogenicity as well. The nitro-oxidative homeostasis imbalance underlies the phytopathogen adaptive strategy and survival in the heavy metal contaminated environment.

In order to get a better understanding of protein association during Solanum tuberosum (cv. Sarpo Mira)–Phytophthora infestans incompatible interaction, we investigated the proteome dynamics of cv. Sarpo Mira, after foliar application of zoospore suspension from P. infestans isolate, at three key time-points: zero hours post inoculation (hpi) (Control), 48 hpi (EI), and 120 hpi (LI); divided into early and late disease stages by the tandem mass tagging (TMT) method. A total of 1229 differentially-expressed proteins (DEPs) were identified in cv. Sarpo Mira in a pairwise comparison of the two disease stages, including commonly shared DEPs, specific DEPs in early and late disease stages, respectively. Over 80% of the changes in protein abundance were up-regulated in the early stages of infection, whereas more DEPs (61%) were down-regulated in the later disease stage. Expression patterns, functional category, and enrichment tests highlighted significant coordination and enrichment of cell wall-associated defense response proteins during the early stage of infection. The late stage was characterized by a cellular protein modification process, membrane protein complex formation, and cell death induction. These results, together with phenotypic observations, provide further insight into the molecular mechanism of P. infestans resistance in potatos.

Late blight disease on potato caused by a plant pathogenic fungus (Phytophthora infestans) is the most important disease in Indonesia. The use of antagonist fungi Trichoderma is an environmentally friendly technology to control the potato disease. The purpose of this study was to determine the ability of Trichoderma spp. to control P. infestans in vitro. Trichoderma spp. have been isolated from suppressive soil at central potato areas in district of Lembang, Bandung, West Java Province. To determine the inhibition ability of Trichoderma spp against P. infestans, a dual culture method was performed. Variable observed was inhibition zone of Trichoderma spp. against P. infestans. The results showed that 9 isolates of Trichoderma were successfuly isolated from suppressive soil, i.e. T. viride (2 isolates), T. atroviride (1 isolate), T. harzianum (1 isolate) and T. aureoviride (5 isolates). All the Trichoderma isolates revealed growth inhibition abality against P. infestans and. The highest growth inhibition (68.6%) was observed by T. viride isolate ( Ti 9).

Pathogens target proteins involved in autophagy to inhibit immune responses in plants.

Plants use autophagy to safeguard against infectious diseases. However, how plant pathogens interfere with autophagy-related processes is unknown. Here, we show that PexRD54, an effector from the Irish potato famine pathogen Phytophthora infestans, binds host autophagy protein ATG8CL to stimulate autophagosome formation. PexRD54 depletes the autophagy cargo receptor Joka2 out of ATG8CL complexes and interferes with Joka2's positive effect on pathogen defense. Thus, a plant pathogen effector has evolved to antagonize a host autophagy cargo receptor to counteract host defenses.

Remote sensing technology becomes an effective and inexpensive technique for detecting disease in vegetation. In this study, an attempt has been done to discriminate healthy and late blight affected crop using remote sensing based indices such as NDVI and LSWI. NDVI and LSWI spectral profiles between healthy and late blight affected crop shows large difference. Mean difference in reflectance between two acquired dates Jan. 10 and 29, 2009 crop clusters varied from 31.28 % in red band, 7.7 % in NIR band and 6.23 % in SWIR bands in healthy crops while in late blight affected crops it is −15.5 % in red, 44.4 % in NIR and −14.61 % in SWIR bands. Negative percentage differences in reflectance indicate reflectance increases from Jan. 10, 2009 to Jan. 29, 2009, while positive difference indicate decrease in reflectance between the two dates. Since potato is an irrigated crop, these differences in reflectance are attributed to prevalent disease at that time. It is found that severely affected areas are Bardhman, Arambag, Bishnupur, Ghatal and Hugli taluka with crop damage areas are 4036.66, 1138.68, 2025.23, 469.15, and 380.08 ha, respectively. [ABSTRACT FROM AUTHOR]

Root-knot nematodes and cyst nematodes are important constraints that reduce potato yields in India. Three species of Meloidogyne cause root-knots on the crop throughout the country, of which, M. incognita is more wide-spread. Infected tubers also result in marketable-yield-loss particularly in the seed potatoes. The cyst nematodes include two species of Globodera restricted to the hilly regions of Tamil Nadu and are of quarantine importance, inhibiting seedpotato production. Potato produce from these hills is used only for consumption. The endoparasitic nature of their life cycle, deposition of eggs into a gelatinous egg mass in root knot and the female turning in to a hard cyst encompassing the eggs within them in cyst nematode makes them difficult organisms to manage. Both these nematodes exhibit physiologic variation, hence, their management is not absolute with host-resistance. Therefore, an Integrated Nematode Management (INM) is adopted in both the cases. Root-knot nematode in North India is managed using nematode-free seed tubers, crop rotation with maize or wheat and application of 1-2 kg ai /ha Carbofuran 3% G at the time of potato planting. Cyst nematode in Tamil Nadu hills is managed by crop rotation with vegetables, particularly cabbage and carrot, intercropping potato with beans or wheat, alternating nematode resistant potato variety 'Kufri Swarna' and application of 2 kg ai /ha Carbofuran 3% G at planting. A two-year adoption of INM for root-knot and a three-year INM practice for cyst nematodes gives efficient and economical production system. Potato farmers in Himachal Pradesh and Tamil Nadu hills follow practices standardized at the Central Potato Research Institute, Shimla and it's substation in the Nilgiri hills.

Late blight caused by Phytophthora infestans is the most important disease attacking potato plants. Four concentrations of essential oils i.e. 0.0, 1.25, 2.5, 5.0 and 7.5 ml/l of Orange, Citral, Methyl antranate (MA), and Terbinol were tested for controlling late blight disease. Results indicate that all treatments except orange oil have an inhibitory effect against the linear growth of P. infestans. Complete reduction in linear growth was obtained with Citral and MA at concentrations of 5.0 and 7.5 ml/l. Other treatments showed moderate effect against P. infestans. In greenhouse experiments, results indicate that all treatments have protective and therapeutic effects against late blight disease except Orange oil which has a protective effect only. High reduction was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which reduced the disease severity by more than 77.1 and 62.8% when applied as protective and therapeutic treatments respectively. Moderate effect was obtained with orange oil and Citral at concentration of 7.5 ml/l for both treatments which reduced the disease severity by more than 65.7% when applied as protective treatments. Similar results were obtained under field coditions; results indicate that all treatments reduced the late blight severity during two growing seasons. High reduction was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which reduced the disease severity by more than 80.0%. As for potato yield, results indicate that all treatments increased potato yield during two growing seasons. A high increase was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which increased the potato yield by more than 59.1%. Other treatments showed a moderate increase. It could be suggested that some essential oils of citrus or their constituents might be used for controlling late blight disease potato plants under field conditions. [ABSTRACT FROM AUTHOR]

Abstract: Proteins embedded in the cell wall and plasma membrane of filamentous oomycetes and fungi provide a means by which these organisms can interact with their local environment. However, cell wall and membrane proteins have often proved difficult to isolate using conventional proteomic techniques. Here we have used liquid chromatography tandem mass spectrometry (LC-MS/MS) to facilitate rapid and sensitive quantification of the cell wall proteome. We report the use of LC-MS/MS to identify differentially regulated proteins from the cell walls of three different lifecycle stages of the oomycete plant pathogen Phytophthora infestans: non-sporulating vegetative mycelium, sporulating mycelium, and germinating cysts with appressoria. We have also used quantitative real-time RT-PCR to confirm that the transcripts corresponding to some of these proteins, namely those identified in cell walls of germinating cysts with appressoria, accumulate differentially throughout the lifecycle. These proteins may, therefore, be important for pre-infective development and early pathogenicity. Up to 31 covalently and non-covalently bound cell wall-associated proteins were identified. All of the proteins identified in germinating cysts with appressoria, and several of those from mycelial fractions, were classified as putative effector or pathogen-associated molecular pattern (PAMP) molecules, including members of the CBEL family, the elicitin family, the crinkler (CRN) family and two transglutaminases. Thus, the cell wall of P. infestans may represent an important reservoir for surface-presented, apoplastic effectors or defence activation molecules. Proteins predicted to be cell surface proteins included IPI-B like proteins, mucins, cell wall-associated enzymes and annexin family members. Additionally we identified up to 27 membrane-associated proteins from Triton X-114 phase partitioned mycelial membrane preparations, producing the first inventory of oomycete membrane-associated proteins. Four of these proteins are small Rab-type G-proteins and several are associated with secretion. [Copyright &y& Elsevier]

Large-scale farming of agricultural crops requires on-time detection of diseases for pest management. Hyperspectral remote sensing data taken from low-altitude flights usually have high spectral and spatial resolutions, which can be very useful in detecting stress in green vegetation. In this study, we used late blight in tomatoes to illustrate the capability of applying hyperspectral remote sensing to monitor crop disease in the field scale and to develop the methodologies for the purpose. A series of field experiments was conducted to collect the canopy spectral reflectance of tomato plants in a diseased tomato field in Salinas Valley of California. The disease severity varied from stage 1 (the light symptom), to stage 4 (the sever damage). The economic damage of the crop caused by the disease is around the disease stage 3. An airborne visible infrared imaging spectrometer (AVIRIS) image with 224 bands within the wavelength range of 0.4–2.5 μm was acquired during the growing season when the field data were collected. The spectral reflectance of the field samples indicated that the near infrared (NIR) region, especially 0.7–1.3 μm, was much more valuable than the visible range to detect crop disease. The difference of spectral reflectance in visible range between health plants and the infected ones at stage 3 was only 1.19%, while the difference in the NIR region was high, 10%. We developed an approach including the minimum noise fraction (MNF) transformation, multi-dimensional visualization, pure pixels endmember selection and spectral angle mapping (SAM) to process the hyperspectral image for identification of diseased tomato plants. The results of MNF transformation indicated that the first 28 eigenimages contain useful information for classification of the pixels and the rest were mainly noise-dominated due to their low eigenvalues that had few signals. Therefore, the 28 signal eigenimages were used to generate a multi-dimensional visualization space for endmember spectra selection and SAM. Classification with the SAM technique of plants’ spectra showed that the late blight diseased tomatoes at stage 3 or above could be separated from the healthy plants while the less infected plants (at stage 1 or 2) were difficult to separate from the healthy plants. The results of the image analysis were consistent with the field spectra. The mapped disease distribution at stage 3 or above from the image showed an accurate conformation of late blight occurrence in the field. This result not only confirmed the capability of hyperspectral remote sensing in detecting crop disease for precision disease management in the real world, but also demonstrated that the spectra-based classification approach is an applicable method to crop disease identification. [Copyright &y& Elsevier]

The aggressiveness of 20 Northern Ireland single-lesion isolates of Phytophthora infestans was compared following their inoculation onto detached leaflets of three potato cultivars chosen on the basis of their differing levels of race-nonspecific resistance to late blight: Bintje (highly susceptible); Cara (moderately resistant); and Stirling (more resistant). Five isolates from outside Northern Ireland were included for comparative purposes: two from the Republic of Ireland; two from the USA (representing the US-1 and US-8 clonal lineages); and one from Mexico. To control the variation between tests, a balanced incomplete block design was used, as opposed to either a complete block design or the method of inclusion of standard isolates, where such variation would have increased the error. Highly significant variation for disease parameters, including latent period, infection frequency, area under the lesion expansion curve (AULEC) and sporulation capacity, was found between isolates. These differences were much more marked on the cultivars exhibiting higher levels of race-nonspecific resistance. There was a significant interaction between isolate and cultivar for all parameters assessed and, overall, no one isolate was the most aggressive across all three potato cultivars. However, a group comprising seven of the 20 Northern Ireland isolates was consistently found to exhibit the highest levels of aggression towards all three cultivars for each of the disease parameters. These results demonstrate that significant variation for foliar aggressiveness exists within the Northern Ireland population of P. infestans , and indicate the importance of selecting appropriately aggressive isolates for evaluation of host resistance to late blight within breeding programmes. [ABSTRACT FROM AUTHOR]

Simple Summary: A potato transgenic event was shown to have complete resistance to late blight, and no other biologically significant differences with the original variety it derives from. Field research, carried out at three locations for three seasons, demonstrates the value this transgenic potato events can deliver to potato farmers in Africa. Transgenic potato event Vic.172, expressing three naturally occurring resistance genes (R genes) conferring complete protection against late blight disease, was evaluated for resistance to late blight, phenotypic characterization, and agronomic performance in field conditions at three locations during three seasons in Uganda. These trials were conducted by comparison to the variety Victoria from which Vic.172 derives, using identical fungicide treatment, except when evaluating disease resistance. During all seasons, the transgenic event Vic.172 was confirmed to have complete resistance to late blight disease, whereas Victoria plants were completely dead by 60–80 days after planting. Tubers from Vic.172 were completely resistant to LB after artificial inoculation. The phenotypic characterization included observations of the characteristics and development of the stems, leaves, flowers, and tubers. Differences in phenotypic parameters between Vic.172 and Victoria were not statistically significant across locations and seasons. The agronomic performance observations covered sprouting, emergence, vigor, foliage growth, and yield. Differences in agronomic performance were not statistically significant except for marketable yield in one location under high productivity conditions. However, yield variation across locations and seasons was not statistically significant, but was influenced by the environment. Hence, the results of the comparative assessment of the phenotype and agronomic performance revealed that transgenic event Vic.172 did not present biologically significant differences in comparison to the variety Victoria it derives from. [ABSTRACT FROM AUTHOR]

Simulator predictions for the effect of oxadixyl and oxadixyl mixtures on the control of late blight in potato crops inoculated with Phytophthora infestans and the buildup of fungal resistance to oxadixyl were compared with data obtained in field experiments. The simulator, which considered fungus, fungicides and crop variables, predicted accurately the effect of fungicide sprays (oxadixyl, oxadixyl mixed with mancozeb, and oxadixyl mixed with mancozeb and cymoxanil) on blight development. The model predicted accurately both resistance buildup and infection in non-treated crops and in crops treated with oxadixyl alone or in a mixture with mancozeb (SAN 518F), but overestimated the control efficacy of the three-way mixture Pulsan. [ABSTRACT FROM AUTHOR]