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1.
Science ; 373(6556): 774-779, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34385392

RESUMO

The oomycete Phytophthora infestans is a damaging crop pathogen and a model organism to study plant-pathogen interactions. We report the discovery of a family of copper-dependent lytic polysaccharide monooxygenases (LPMOs) in plant pathogenic oomycetes and its role in plant infection by P. infestans We show that LPMO-encoding genes are up-regulated early during infection and that the secreted enzymes oxidatively cleave the backbone of pectin, a charged polysaccharide in the plant cell wall. The crystal structure of the most abundant of these LPMOs sheds light on its ability to recognize and degrade pectin, and silencing the encoding gene in P. infestans inhibits infection of potato, indicating a role in host penetration. The identification of LPMOs as virulence factors in pathogenic oomycetes opens up opportunities in crop protection and food security.


Assuntos
Lycopersicon esculentum/parasitologia , Oxigenases de Função Mista/metabolismo , Pectinas/metabolismo , Phytophthora infestans/enzimologia , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Cobre , Oxigenases de Função Mista/química , Oxigenases de Função Mista/genética , Modelos Moleculares , Oxirredução , Phytophthora infestans/genética , Phytophthora infestans/patogenicidade , Folhas de Planta/parasitologia , Polissacarídeos/metabolismo , Conformação Proteica , Domínios Proteicos , Fatores de Virulência/química , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
2.
PLoS One ; 16(7): e0241256, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34260582

RESUMO

Potato cyst nematodes (PCN) from the genus Globodera spp. cause major losses in the potato (Solanum tuberosum) industry worldwide. Despite their importance, at present little is known about the status of this plant pathogen in cultivated potatoes in Colombia. In this study, a total of 589 samples collected from 75 geographic localities in nine potato producing regions of Colombia (Cundinamarca, Boyacá, Antioquia, Nariño, Santander, Norte de Santander, Tolima, Caldas and Cauca) were assayed for the presence of potato cyst nematodes. Fifty-seven percent of samples tested positive for PCN. Based on phylogenetic analysis of the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rRNA gene and D2-D3 expansion segments of the 28S rRNA gene, all populations but one were identified as Globodera pallida. Sequences of G. pallida from Colombia formed a monophyletic group closely related to Peruvian populations, with the lowest average number of nucleotide substitutions per site (Dxy = 0.002) and net nucleotide substitutions per site (Da = 0.001), when compared to G. pallida populations from Europe, South and North America. A single sample formed a well-supported subclade along with G. rostochiensis and G. tabacum from Japan, USA and Argentina. To our knowledge this is the first comprehensive survey of Globodera populations from Colombia that includes genetic data. Our findings on species diversity and phylogenetic relationships of Globodera populations from Colombia may help elucidate the status and distribution of Globodera species, and lead to the development of accurate management strategies for the potato cyst nematodes.


Assuntos
Produtos Agrícolas/parasitologia , Filogenia , Solanum tuberosum/parasitologia , Tylenchoidea/fisiologia , Animais , Colômbia , Doenças das Plantas
3.
Molecules ; 26(10)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34069787

RESUMO

We evaluated photosystem II (PSII) functionality in potato plants (Solanum tuberosum L.) before and after a 15 min feeding by the leaf miner Tuta absoluta using chlorophyll a fluorescence imaging analysis combined with reactive oxygen species (ROS) detection. Fifteen minutes after feeding, we observed at the feeding zone and at the whole leaf a decrease in the effective quantum yield of photosystem II (PSII) photochemistry (ΦPSII). While at the feeding zone the quantum yield of regulated non-photochemical energy loss in PSII (ΦNPQ) did not change, at the whole leaf level there was a significant increase. As a result, at the feeding zone a significant increase in the quantum yield of non-regulated energy loss in PSII (ΦNO) occurred, but there was no change at the whole leaf level compared to that before feeding, indicating no change in singlet oxygen (1O2) formation. The decreased ΦPSII after feeding was due to a decreased fraction of open reaction centers (qp), since the efficiency of open PSII reaction centers to utilize the light energy (Fv'/Fm') did not differ before and after feeding. The decreased fraction of open reaction centers resulted in increased excess excitation energy (EXC) at the feeding zone and at the whole leaf level, while hydrogen peroxide (H2O2) production was detected only at the feeding zone. Although the whole leaf PSII efficiency decreased compared to that before feeding, the maximum efficiency of PSII photochemistry (Fv/Fm), and the efficiency of the water-splitting complex on the donor side of PSII (Fv/Fo), did not differ to that before feeding, thus they cannot be considered as sensitive parameters to monitor biotic stress effects. Chlorophyll fluorescence imaging analysis proved to be a good indicator to monitor even short-term impacts of insect herbivory on photosynthetic function, and among the studied parameters, the reduction status of the plastoquinone pool (qp) was the most sensitive and suitable indicator to probe photosynthetic function under biotic stress.


Assuntos
Enterobius/fisiologia , Luz , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/parasitologia , Folhas de Planta/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Solanum tuberosum/parasitologia , Solanum tuberosum/efeitos da radiação , Animais , Transporte de Elétrons , Comportamento Alimentar , Peróxido de Hidrogênio/metabolismo , Teoria Quântica
4.
PLoS Pathog ; 17(4): e1009477, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33857257

RESUMO

The lack of efficient methods to control the major diseases of crops most important to agriculture leads to huge economic losses and seriously threatens global food security. Many of the most important microbial plant pathogens, including bacteria, fungi, and oomycetes, secrete necrosis- and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs), which critically contribute to the virulence and spread of the disease. NLPs are cytotoxic to eudicot plants, as they disturb the plant plasma membrane by binding to specific plant membrane sphingolipid receptors. Their pivotal role in plant infection and broad taxonomic distribution makes NLPs a promising target for the development of novel phytopharmaceutical compounds. To identify compounds that bind to NLPs from the oomycetes Pythium aphanidermatum and Phytophthora parasitica, a library of 587 small molecules, most of which are commercially unavailable, was screened by surface plasmon resonance. Importantly, compounds that exhibited the highest affinity to NLPs were also found to inhibit NLP-mediated necrosis in tobacco leaves and Phytophthora infestans growth on potato leaves. Saturation transfer difference-nuclear magnetic resonance and molecular modelling of the most promising compound, anthranilic acid derivative, confirmed stable binding to the NLP protein, which resulted in decreased necrotic activity and reduced ion leakage from tobacco leaves. We, therefore, confirmed that NLPs are an appealing target for the development of novel phytopharmaceutical agents and strategies, which aim to directly interfere with the function of these major microbial virulence factors. The compounds identified in this study represent lead structures for further optimization and antimicrobial product development.


Assuntos
Phytophthora/patogenicidade , Doenças das Plantas/prevenção & controle , Pythium/patogenicidade , Solanum tuberosum/genética , Simulação de Dinâmica Molecular , Necrose , Phytophthora/genética , Doenças das Plantas/parasitologia , Folhas de Planta/genética , Folhas de Planta/parasitologia , Pythium/genética , Solanum tuberosum/parasitologia , Ressonância de Plasmônio de Superfície , Tabaco/genética , Tabaco/parasitologia
5.
Mol Plant Pathol ; 22(5): 495-507, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33709540

RESUMO

TAXONOMY: Phylum Nematoda; class Chromadorea; order Rhabditida; suborder Tylenchina; infraorder Tylenchomorpha; superfamily Tylenchoidea; family Heteroderidae; subfamily Heteroderinae; Genus Globodera. BIOLOGY: Potato cyst nematodes (PCN) are biotrophic, sedentary endoparasitic nematodes. Invasive (second) stage juveniles (J2) hatch from eggs in response to the presence of host root exudates and subsequently locate and invade the host. The nematodes induce the formation of a large, multinucleate syncytium in host roots, formed by fusion of up to 300 root cell protoplasts. The nematodes rely on this single syncytium for the nutrients required to develop through a further three moults to the adult male or female stage. This extended period of biotrophy-between 4 and 6 weeks in total-is almost unparalleled in plant-pathogen interactions. Females remain at the root while adult males revert to the vermiform body plan of the J2 and leave the root to locate and fertilize the female nematodes. The female body forms a cyst that contains the next generation of eggs. HOST RANGE: The host range of PCN is limited to plants of the Solanaceae family. While the most economically important hosts are potato (Solanum tuberosum), tomato (Solanum lycopersicum), and aubergine (Solanum melongena), over 170 species of Solanaceae are thought to be potential hosts for PCN (Sullivan et al., 2007). DISEASE SYMPTOMS: Symptoms are similar to those associated with nutrient deficiency, such as stunted growth, yellowing of leaves and reduced yields. This absence of specific symptoms reduces awareness of the disease among growers. DISEASE CONTROL: Resistance genes (where available in suitable cultivars), application of nematicides, crop rotation. Great effort is put into reducing the spread of PCN through quarantine measures and use of certified seed stocks. USEFUL WEBSITES: Genomic information for PCN is accessible through WormBase ParaSite.


Assuntos
Genoma Helmíntico/genética , Interações Hospedeiro-Parasita , Lycopersicon esculentum/parasitologia , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Tylenchoidea/fisiologia , Animais , Resistência à Doença/genética , Feminino , Genômica , Especificidade de Hospedeiro/genética , Lycopersicon esculentum/genética , Lycopersicon esculentum/imunologia , Masculino , Doenças das Plantas/prevenção & controle , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Raízes de Plantas/genética , Raízes de Plantas/imunologia , Raízes de Plantas/parasitologia , Solanum tuberosum/genética , Solanum tuberosum/imunologia , Tylenchoidea/genética
6.
Sci Rep ; 11(1): 6523, 2021 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-33753776

RESUMO

Insecticidal double-stranded RNAs (dsRNAs) silence expression of vital genes by activating the RNA interference (RNAi) mechanism in insect cells. Despite high commercial interest in insecticidal dsRNA, information on resistance to dsRNA is scarce, particularly for dsRNA products with non-transgenic delivery (ex. foliar/topical application) nearing regulatory review. We report the development of the CEAS 300 population of Colorado potato beetle (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) with > 11,100-fold resistance to a dsRNA targeting the V-ATPase subunit A gene after nine episodes of selection using non-transgenic delivery by foliar coating. Resistance was associated with lack of target gene down-regulation in CEAS 300 larvae and cross-resistance to another dsRNA target (COPI ß; Coatomer subunit beta). In contrast, CEAS 300 larvae showed very low (~ 4-fold) reduced susceptibility to the Cry3Aa insecticidal protein from Bacillus thuringiensis. Resistance to dsRNA in CEAS 300 is transmitted as an autosomal recessive trait and is polygenic. These data represent the first documented case of resistance in an insect pest with high pesticide resistance potential using dsRNA delivered through non-transgenic techniques. Information on the genetics of resistance and availability of dsRNA-resistant L. decemlineata guide the design of resistance management tools and allow research to identify resistance alleles and estimate resistance risks.


Assuntos
Besouros/efeitos dos fármacos , Resistência a Medicamentos/genética , Inseticidas/farmacologia , RNA de Cadeia Dupla/farmacologia , Animais , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis/farmacologia , Besouros/genética , Besouros/patogenicidade , Colorado , Endotoxinas/genética , Endotoxinas/farmacologia , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/genética , Larva/genética , Larva/crescimento & desenvolvimento , Interferência de RNA , RNA de Cadeia Dupla/genética , Solanum tuberosum/crescimento & desenvolvimento , Solanum tuberosum/parasitologia
7.
Mol Plant Pathol ; 22(6): 737-752, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33724663

RESUMO

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.


Assuntos
Edição de Genes , Phytophthora infestans/genética , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Alelos , Sistemas CRISPR-Cas , Cromatina/genética , Genômica , Phytophthora infestans/fisiologia
8.
Mol Plant Pathol ; 22(6): 644-657, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33764635

RESUMO

A cascade formed by phosphorylation events of mitogen-activated protein kinases (MAPKs) takes part in plant stress responses. However, the roles of these MAPKs in resistance of potato (Solanum tuberosum) against Phytophthora pathogens is not well studied. Our previous work showed that a Phytophthora infestans RXLR effector targets and stabilizes the negative regulator of MAPK kinase 1 of potato (StMKK1). Because in Arabidopsis thaliana the AtMPK4 is the downstream phosphorylation target of AtMKK1, we performed a phylogenetic analysis and found that potato StMPK4/6/7 are closely related and are orthologs of AtMPK4/5/11/12. Overexpression of StMPK4/7 enhances plant resistance to P. infestans and P. parasitica. Yeast two-hybrid analysis revealed that StMPK7 interacts with StMKK1, and StMPK7 is phosphorylated on flg22 treatment and by expressing constitutively active StMKK1 (CA-StMKK1), indicating that StMPK7 is a direct downstream signalling partner of StMKK1. Overexpression of StMPK7 in potato enhances potato resistance to P. infestans. Constitutively active StMPK7 (CA-StMPK7; StMPK7D198G, E202A ) was found to promote immunity to Phytophthora pathogens and to trigger host cell death when overexpressed in Nicotiana benthamiana leaves. Cell death triggered by CA-StMPK7 is SGT1/RAR1-dependent. Furthermore, cell death triggered by CA-StMPK7 is suppressed on coexpression with the salicylate hydroxylase NahG, and StMPK7 activation promotes salicylic acid (SA)-responsive gene expression. We conclude that potato StMPK7 is a downstream signalling component of the phosphorelay cascade involving StMKK1 and StMPK7 plays a role in immunity to Phytophthora pathogens via an SA-dependent signalling pathway.


Assuntos
Resistência à Doença , Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Phytophthora infestans/fisiologia , Doenças das Plantas/imunologia , Solanum tuberosum/genética , Morte Celular , Expressão Gênica , Proteínas Quinases Ativadas por Mitógeno/genética , Filogenia , Doenças das Plantas/parasitologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ácido Salicílico/metabolismo , Solanum tuberosum/imunologia , Solanum tuberosum/parasitologia , Tabaco/genética , Tabaco/imunologia , Tabaco/parasitologia
9.
Folia Microbiol (Praha) ; 66(4): 555-567, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33788146

RESUMO

Phytophthora infestans is the pathogen of potato late blight, which is one of the most serious diseases of the potato. Myxobacteria, especially Myxococcus, become a valuable biological control resource due to their preponderant abilities to produce various secondary metabolites with novel structure and remarkable biological activity. In a previous study, Myxococcus fulvus B25-I-3 with antagonistic activity against P. infestans was isolated from an environmental sample by rabbit fecal induction method. The biocontrol mechanism of M. fulvus B25-I-3 against P. infestans and its control efficiency on potato late blight were studied. The results showed that the active substances produced by strain B25-I-3 had strong inhibitory effect on the asexual reproduction and sexual reproduction of P. infestans. In addition, the active substances could reduce the content of soluble proteins and the activity of the protective enzymes (polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, superoxide dismutase) in P. infestans and increase the oxidative damage and permeability of cell membrane. And the active substances could inhibit the infection of the detached potato leaves by P. infestans significantly. In conclusion, M. fulvus B25-I-3 can produce active substances against P. infestans and has potential value to develop into biological pesticides for the control of potato late blight. The completion of this work may provide basic data for the isolation and identification of active substances and the development of pesticides against potato late blight.


Assuntos
Myxococcus , Controle Biológico de Vetores , Phytophthora infestans , Doenças das Plantas , Solanum tuberosum , Interações Microbianas/fisiologia , Myxococcus/fisiologia , Controle Biológico de Vetores/métodos , Phytophthora infestans/fisiologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Solanum tuberosum/microbiologia , Solanum tuberosum/parasitologia
10.
Sci Rep ; 11(1): 6266, 2021 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-33737607

RESUMO

Tuber infection of Phytophthora infestans often occurs at harvest. However, it is difficult to accurately estimate the population densities of P. infestans in soil, especially Japanese soil. In the present study, P. infestans DNA was extracted from soil samples using a modified CTAB-bead method and quantified using real-time PCR to accurately, rapidly and easily estimate the P. infestans population densities in upland soils in Japan. P. infestans was well quantified in eleven types of soil samples, including nine types of upland soils in Japan, that were artificially inoculated with a zoosporangia suspension. The amounts of P. infestans DNA estimated by the real-time PCR were proportional to the inoculum densities. In the non-controlled experimental potato field, P. infestans population densities in soil corresponded to the development of symptoms and were correlated with the number of lesions on the potato foliage. These results imply that the proposed real-time PCR assay is suitable for the estimation or monitoring of P. infestans population densities in upland soils in Japan. The population densities at the ridge bottoms were larger than those at any other location in commercial potato fields. These results were similar to those of a previous report using a bioassay. Moreover, a correlation between DNA quantity and inoculum potential was observed. In conclusion, the real-time PCR assay developed in this study is suitable for indirect estimation of the inoculum potential of P. infestans.


Assuntos
Phytophthora infestans/genética , Doenças das Plantas/parasitologia , Tubérculos/parasitologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Microbiologia do Solo , Solo/parasitologia , Solanum tuberosum/parasitologia , DNA/genética , DNA/isolamento & purificação , Japão
11.
Sci Rep ; 11(1): 628, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436688

RESUMO

This study was conducted to determine the root system architecture and biochemical responses of three potato (Solanum tuberosum L.) cultivars to drought and aphid (Myzus persicae Sulzer) infestation under greenhouse conditions. A factorial experiment comprising three potato cultivars (Qingshu 9, Longshu 3, and Atlantic), two levels of water (Well watered and drought) application and aphid infestation (Aphids and no aphids) was conducted. The results show that drought stress and aphid infestation significantly increased the root-projected area, root surface area, number of root tips, and number of root forks of all cultivars, relative to their corresponding control plants. The least root projected area, root surface area, number of root tips, and number of root forks occurred on DXY under both drought and aphid infestation. Nevertheless, the greatest root projected area, root surface area, number of root tips and number of root forks occurred on QS9 plants. Moreover, increased SOD, CAT, and POD activities were observed across all cultivars, under drought and aphid stress. The highest SOD, POD, and CAT activities occurred in QS9; under drought and aphid stress, while the least SOD, POD, and CAT activities was observed in DXY. The Atlantic cultivar, which possesses a root system sensitive to water deficit, demonstrated greater resistance to aphid infestation under well-watered and drought-stressed conditions. Conversely, Qingshu 9, which possesses a root system tolerant to water deficit, was highly susceptible to aphids. This study shows that the root architectural and biochemical traits that enhance potato tolerance to drought do not necessarily correlate to a plant's tolerance to aphids.


Assuntos
Antioxidantes/metabolismo , Afídeos/fisiologia , Secas , Regulação Enzimológica da Expressão Gênica , Folhas de Planta/imunologia , Solanum tuberosum/imunologia , Estresse Fisiológico , Animais , Folhas de Planta/parasitologia , Solanum tuberosum/enzimologia , Solanum tuberosum/parasitologia
12.
Mol Plant Pathol ; 22(1): 48-63, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33118686

RESUMO

Nonspecific lipidtransfer proteins (nsLTPs), which are small, cysteine-rich proteins, belong to the pathogenesis-related protein family, and several of them act as positive regulators during plant disease resistance. However, the underlying molecular mechanisms of these proteins in plant immune responses are unclear. In this study, a typical nsLTP gene, StLTP10, was identified and functionally analysed in potato. StLTP10 expression was significantly induced by Phytophthora infestans, which causes late blight in potato, and defence-related phytohormones, including abscisic acid (ABA), salicylic acid, and jasmonic acid. Characterization of StLTP10-overexpressing and knockdown lines indicated that StLTP10 positively regulates plant resistance to P. infestans. This resistance was coupled with enhanced expression of reactive oxygen species scavenging- and defence-related genes. Furthermore, we identified that StLTP10 physically interacts with ABA receptor PYL4 and affects its subcellular localization. These two proteins work together to regulate stomatal closure during pathogen infection. Interestingly, we also found that wound-induced protein kinase interacts with StLTP10 and positively regulates its protein abundance. Taken together, our results provide insight into the role of StLTP10 in resistance to P. infestans and suggest candidates to enhance broad-spectrum resistance to pathogens in potato.


Assuntos
Proteínas de Transporte/metabolismo , Resistência à Doença/genética , Phytophthora infestans/fisiologia , Doenças das Plantas/imunologia , Solanum tuberosum/genética , Ácido Abscísico/metabolismo , Proteínas de Transporte/genética , Doenças das Plantas/parasitologia , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/genética , Estômatos de Plantas/imunologia , Estômatos de Plantas/parasitologia , Ácido Salicílico/metabolismo , Solanum tuberosum/imunologia , Solanum tuberosum/parasitologia
14.
Gene ; 766: 145159, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32971186

RESUMO

Considering the relevance of insect α-amylases and natural α-amylase inhibitors present in plants to protect against insect damage, we investigated the effect of white bean and rapeseed protein extracts on digestive α-amylase gene expression of the Colorado potato beetle, Leptinotarsa decemlineata (Say). For this purpose, in vitro and in vivo trials were performed to determine the inhibitory activity of seed proteins on the third and fourth instar larvae. In both trials, the significant inhibitory effect of each extracts on the third and fourth instar larval α-amylase activity and considerable mortality in treatments were observed compared to control trials. In the RT-qPCR, expression ratio demonstrated that the α-amylase gene of two different larval stages grown on both proteins treated leaves had significantly differentiated expression and was up-regulated in third instar larvae and down-regulated in fourth instar larvae compared to control. Results suggest that the hyper-production of α-amylase in third instar larvae is elicited to compensate for the enzyme activity inhibition at an earlier stage and also down-regulation suggests the existence of a negative feedback of plant proteins on the last instar larvae via impaired food intake and digestive α-amylase activity in Colorado potato beetle. Therefore, disruption of the insect's digestive physiology by plant defensive proteins can be considered in the development of innovative controlling methods of this crucial potato pest.


Assuntos
Besouros/efeitos dos fármacos , Besouros/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Larva/efeitos dos fármacos , Extratos Vegetais/farmacologia , Proteínas de Plantas/farmacologia , alfa-Amilases/genética , Animais , Digestão/efeitos dos fármacos , Digestão/genética , Regulação da Expressão Gênica/genética , Larva/genética , Folhas de Planta/química , Solanum tuberosum/parasitologia
15.
Genes (Basel) ; 11(12)2020 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-33260722

RESUMO

Although the use of natural resistance is the most effective management approach against the potato cyst nematode (PCN) Globodera pallida, the existence of pathotypes with different virulence characteristics constitutes a constraint towards this goal. Two resistance sources, GpaV (from Solanum vernei) and H3 from S. tuberosum ssp. andigena CPC2802 (from the Commonwealth Potato Collection) are widely used in potato breeding programmes in European potato industry. However, the use of resistant cultivars may drive strong selection towards virulence, which allows the increase in frequency of virulent alleles in the population and therefore, the emergence of highly virulent nematode lineages. This study aimed to identify Avirulence (Avr) genes in G. pallida populations selected for virulence on the above resistance sources, and the genomic impact of selection processes on the nematode. The selection drive in the populations was found to be specific to their genetic background. At the genomic level, 11 genes were found that represent candidate Avr genes. Most of the variant calls determining selection were associated with H3-selected populations, while many of them seem to be organised in genomic islands facilitating selection evolution. These phenotypic and genomic findings combined with histological studies performed revealed potential mechanisms underlying selection in G. pallida.


Assuntos
Nematoides , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Animais , Resistência à Doença , Nematoides/genética , Nematoides/patogenicidade , Virulência
16.
Sci Rep ; 10(1): 21294, 2020 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-33277549

RESUMO

Ethylene (ET) is one of the many important signaling hormones that functions in regulating defense responses in plants. Gene expression profiling was conducted under exogenous ET application in the high late blight resistant potato genotype SD20 and the specific transcriptional responses to exogenous ET in SD20 were revealed. Analysis of differentially expressed genes (DEGs) generated a total of 1226 ET-specific DEGs, among which transcription factors, kinases, defense enzymes and disease resistance-related genes were significantly differentially expressed. GO enrichment and KEGG metabolic pathway analysis also revealed that numerous defense regulation-related genes and defense pathways were significantly enriched. These results were consistent with the interaction of SD20 and Phytophthora infestans in our previous study, indicating that exogenous ET stimulated the defense response and initiated a similar defense pathway compared to pathogen infection in SD20. Moreover, multiple signaling pathways including ET, salicylic acid, jasmonic acid, abscisic acid, auxin, cytokinin and gibberellin were involved in the response to exogenous ET, which indicates that many plant hormones work together to form a complex network to resist external stimuli in SD20. ET-induced gene expression profiling provides insights into the ET signaling transduction pathway and its potential mechanisms in disease defense systems in potato.


Assuntos
Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Parasita , Phytophthora infestans/fisiologia , Solanum tuberosum/imunologia , Perfilação da Expressão Gênica , Doenças das Plantas , Reguladores de Crescimento de Plantas/metabolismo , Transdução de Sinais , Solanum tuberosum/metabolismo , Solanum tuberosum/parasitologia , Fatores de Transcrição/metabolismo
17.
PLoS Pathog ; 16(10): e1008884, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33007049

RESUMO

Plant parasitic nematodes are microscopic pathogens that invade plant roots and cause extensive damage to crops. We have used a chemical biology approach to define mechanisms underpinning their parasitic behaviour: We discovered that reserpine, a plant alkaloid that inhibits the vesicular monoamine transporter (VMAT), potently impairs the ability of the potato cyst nematode Globodera pallida to enter the host plant root. We show this is due to an inhibition of serotonergic signalling that is essential for activation of the stylet which is used to access the host root. Prompted by this we identified core molecular components of G. pallida serotonin signalling encompassing the target of reserpine, VMAT; the synthetic enzyme for serotonin, tryptophan hydroxylase; the G protein coupled receptor SER-7 and the serotonin-gated chloride channel MOD-1. We cloned each of these molecular components and confirmed their functional identity by complementation of the corresponding C. elegans mutant thus mapping out serotonergic signalling in G. pallida. Complementary approaches testing the effect of chemical inhibitors of each of these signalling elements on discrete sub-behaviours required for parasitism and root invasion reinforce the critical role of serotonin. Thus, targeting the serotonin signalling pathway presents a promising new route to control plant parasitic nematodes.


Assuntos
Proteção de Cultivos/métodos , Interações Hospedeiro-Patógeno , Nematoides/fisiologia , Doenças das Plantas/parasitologia , Serotonina/metabolismo , Transdução de Sinais , Solanum tuberosum/metabolismo , Animais , Solanum tuberosum/parasitologia
18.
Int J Mol Sci ; 21(21)2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33126590

RESUMO

Citral is well known for its antimicrobial, antifungal, and insecticidal activities. Natural sesquiterpene α-methylenelactones also exhibit a broad spectrum of biological activities. The aim of the study was to explore the effect of structural changes to citral molecules on citral behavior-modifying activity towards Myzus persicae. Specifically, the effects of the introduction of a γ-lactone moiety and methylene groups in α and γ positions of the lactone ring were investigated. The lactones were obtained in five-step (saturated lactone and γ-methylenelactone) or six-step (α-methylenelactone and α,γ-dimethylenelactone) syntheses from citral. The synthetic procedures and physical and spectral data of the lactones are presented. The settling behavior of freely moving aphids in choice and no-choice situations was monitored. The probing behavior of tethered M. persicae using the Electrical Penetration Graph (EPG) technique was also analyzed. Citral appeared a strong repellent and pre-ingestive and ingestive probing deterrent to M. persicae. The incorporation of a lactone moiety caused the loss of the repellent activity. α-Methylenelactone inhibited aphid settling and probing activities at pre-ingestive and ingestive phases. The saturated γ-lactone and α,γ-dimethylenelactone were the settling post-ingestive deterrents to M. persicae, which did not affect aphid probing activity. γ-Methylenelactone did not affect aphid behavior.


Assuntos
Monoterpenos Acíclicos/química , Afídeos/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Inseticidas/farmacologia , Lactonas/farmacologia , Solanum tuberosum/crescimento & desenvolvimento , Animais , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/parasitologia
19.
J Helminthol ; 94: e188, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32907645

RESUMO

The potato tuber moth, Phthorimaea operculella (Zeller), is a serious pest of potato and other commercial crops belonging to the Solanaceae family. In recent years, it has become an emerging problem in potato-growing regions of the Nilgiri hills of southern India. It is responsible for the reduced quality and quantity of marketable potatoes. In this regard, the development of an eco-friendly control method for the management of the potato tuber moth is urgently required. Therefore, in the present study, the virulence of Steinernema cholashanense CPRSUS01 originally isolated from the potato rhizosphere was tested on fourth-instar larvae and pupae of P. operculella. Steinernema cholashanense caused the greatest mortality in the fourth-instar larval stage (100%) than the pupae (30%). In addition to this, penetration and reproduction of this nematode was also studied in fourth-instar larvae of P. operculella and this is the first report of penetration and reproduction of any entomopathogenic nematode species on potato tuber moth larvae. The reproduction capacity of S. cholashanense on P. operculella is higher (702 infective juveniles mg-1 body weight). Our results indicated that S. cholashanense has good potential as an alternative tool for the management of P. operculella. But before including S. cholashanense in the integrated pest management program of P. operculella, its efficacy should be tested under field conditions.


Assuntos
Mariposas/parasitologia , Controle Biológico de Vetores , Rabditídios/patogenicidade , Solanum tuberosum/parasitologia , Animais , Feminino , Índia , Larva/parasitologia , Doenças das Plantas/prevenção & controle , Pupa/parasitologia , Rabditídios/isolamento & purificação , Rizosfera
20.
Mol Plant Pathol ; 21(11): 1502-1512, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32935441

RESUMO

Potato late blight, caused by the oomycete pathogen Phytophthora infestans, significantly hampers potato production. Recently, a new Resistance to Phytophthora infestans (Rpi) gene, Rpi-amr1, was cloned from a wild Solanum species, Solanum americanum. Identification of the corresponding recognized effector (Avirulence or Avr) genes from P. infestans is key to elucidating their naturally occurring sequence variation, which in turn informs the potential durability of the cognate late blight resistance. To identify the P. infestans effector recognized by Rpi-amr1, we screened available RXLR effector libraries and used long read and cDNA pathogen-enrichment sequencing (PenSeq) on four P. infestans isolates to explore the untested effectors. Using single-molecule real-time sequencing (SMRT) and cDNA PenSeq, we identified 47 highly expressed effectors from P. infestans, including PITG_07569, which triggers a highly specific cell death response when transiently coexpressed with Rpi-amr1 in Nicotiana benthamiana, suggesting that PITG_07569 is Avramr1. Here we demonstrate that long read and cDNA PenSeq enables the identification of full-length RXLR effector families and their expression profile. This study has revealed key insights into the evolution and polymorphism of a complex RXLR effector family that is associated with the recognition by Rpi-amr1.


Assuntos
Phytophthora infestans/genética , Doenças das Plantas/parasitologia , Polimorfismo Genético/genética , Solanum tuberosum/parasitologia , Proteínas de Algas/genética , Proteínas de Algas/metabolismo , Morte Celular , DNA Complementar/genética , Phytophthora infestans/patogenicidade , Solanum/virologia , Tabaco/virologia
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