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1.
Planta ; 254(6): 128, 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34812941

RESUMO

MAIN CONCLUSION: Soybean contains a group of 64 L-type lectin receptor-like kinases. Three LecRKs were involved in the interactions with Phytophthora sojae and Bradyrhizobium diazoefficiens. L-type lectin receptor-like kinases (LecRKs) comprise an important class of membrane-localized receptor-like kinases that are involved in plant adaptation. In this study, we performed an inventory analysis of LecRKs in Glycine max (soybean). In total, 64 GmLecRKs containing the canonical LecRK feature were identified. Phylogenetic analysis revealed that 48 GmLecRKs have close orthologs in Arabidopsis or Solanum lycopersicum, while 16 are likely present only in the leguminous plant species. Transcriptome analyses revealed that expressions of multiple GmLecRK genes are either induced or suppressed during infection by the soybean root rot pathogen Phytophthora sojae. In addition, overexpression of the three LecRKs (Glyma.17G085000, Glyma.05G041300 or Glyma.17G224600) in the soybean hairy roots enhanced resistance to P. sojae. Upon inoculation with Bradyrhizobium diazoefficiens, overexpression of Glyma.17G085000 in the soybean hairy roots does not significantly influence the nodulation, while overexpression of Glyma.05G041300 or Glyma.17G224600 slightly reduced the number and dry weight of nodules. This study highlights the importance of LecRKs in regulating plant-microbe interactions and provides new knowledge on the deployment of LecRKs to increase resistance in soybean.


Assuntos
Phytophthora , Bradyrhizobium , Resistência à Doença , Lectinas , Filogenia , Doenças das Plantas , Soja/genética
2.
Plant Sci ; 313: 111082, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34763867

RESUMO

Studies show that DNA methylation is associated with plant immunity but little is known as to how this epigenetic mechanism assists plants in adjusting their responses to biotic stress, especially when interacting with an hemibiotrophic pathogen such as citrus Phytophthora. The aim of the present study was to assess the effects of scion-rootstock interaction on plant resistance to P. citrophthora infection and DNA methylation patterns in 'Pera' sweet orange and 'Tahiti' acid lime grafted onto 'Rangpur' lime and 'Tropical' sunki rootstocks reinoculated with P. citrophthora. Results showed that reinoculated plants of the 'Pera' sweet orange/'Rangpur' lime and 'Tahiti' acid lime/'Tropical' sunki combinations with more and less sensitive varieties to Phytophthora, presented smaller stem lesions and increased frequency of full methylation and hemimethylation rates, compared to inoculated plants. In contrast, 'Tahiti' acid lime/'Rangpur' lime, two highly sensitive varieties, and 'Pera'/'Tropical' sunki, two much less sensitive varieties, showed high increases in the frequency of hemimethylation and non-methylation levels. Results suggest that in citrus, both the scion-rootstock interaction and DNA methylation affect the response to P. citrophthora infection. Reinoculated plants, depending on the combination, showed changes in intracellular hyphae growth through the formation of sets of fibers and crystal accumulation in the periderm, cortex, and phloem. In addition, starch grain concentration was higher in reinoculated plants in comparison to inoculated plants. These findings support the assumption that DNA methylation is a plant defense mechanism and therefore may be exploited to improve the response of plants to the gummosis of P. citrophthora in citrus.


Assuntos
Citrus aurantiifolia/genética , Citrus aurantiifolia/microbiologia , Citrus sinensis/genética , Citrus sinensis/microbiologia , Resistência à Doença/genética , Phytophthora/patogenicidade , Doenças das Plantas/genética , Epigênese Genética , Variação Genética , Genótipo
3.
Int J Mol Sci ; 22(19)2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34638807

RESUMO

Calcium signals are crucial for the activation and coordination of signaling cascades leading to the establishment of plant defense mechanisms. Here, we studied the contribution of CML8, an Arabidopsis calmodulin-like protein in response to Ralstonia solanacearum and to pathogens with different lifestyles, such as Xanthomonas campestris pv. campestris and Phytophtora capsici. We used pathogenic infection assays, gene expression, RNA-seq approaches, and comparative analysis of public data on CML8 knockdown and overexpressing Arabidopsis lines to demonstrate that CML8 contributes to defense mechanisms against pathogenic bacteria and oomycetes. CML8 gene expression is finely regulated at the root level and manipulated during infection with Ralstonia, and CML8 overexpression confers better plant tolerance. To understand the processes controlled by CML8, genes differentially expressed at the root level in the first hours of infection have been identified. Overexpression of CML8 also confers better tolerance against Xanthomonas and Phytophtora, and most of the genes differentially expressed in response to Ralstonia are differentially expressed in these different pathosystems. Collectively, CML8 acts as a positive regulator against Ralstonia solanaceraum and against other vascular or root pathogens, suggesting that CML8 is a multifunctional protein that regulates common downstream processes involved in the defense response of plants to several pathogens.


Assuntos
Arabidopsis/metabolismo , Cálcio/metabolismo , Resistência à Doença , Doenças das Plantas , Transdução de Sinais , Arabidopsis/imunologia , Arabidopsis/microbiologia , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Phytophthora , Ralstonia solanacearum , Xanthomonas campestris
4.
Phytochemistry ; 190: 112884, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34388481

RESUMO

This study analyzed the genetic variability and biochemical characteristics of edible and ornamental accessions of pepper, Capsicum annuum, in response to root and basal rot disease (RCR), caused by Phytophthora capsici, using resistance screening and genetic variability via Inter Simple Sequence Repeat marker (ISSR), bio-mass parameters, and enzymatic activity of Peroxidase or peroxide reductases (POX), Superoxide dismutase (SOD), Polyphenol oxidase (PPOs), Catalase (CAT), Phenylalanine ammonia-lyase (PAL), ß-1,3-glucanase and phenolic content. The resistance in C. annuum '37ChilPPaleo', '19OrnP-PBI' and '23CherryPOrsh' and susceptibility in '2BP-PBI', '24BP-301' and '26BPRStarlet' accessions were confirmed. Nineteen out of 21 ISSR primers generated 185 polymorphic bands with a mean percentage band of 98.5 %, and an average number of bands of 9.9 per primer. Biomass parameters were significantly higher in resistant genotypes than the susceptible ones and non-inoculated controls. All the seven candidate enzymes were highly up-regulated in the resistant C. annuum accessions '19OrnP-PBI', '37ChillP-Paleo' and '23CherryP-Orsh' inoculated with P. capsici The mean level of enzyme activity varied from 1.5 to 5.6-fold higher in the resistant C. annuum, of which SOD was increased by 5.6 fold, followed by PAL 4.40 and PPO 3.75 fold in comparison to susceptible and non-inoculated controls. Overall, there was no significant correlation between resistance and genetic variability, and also between genetic variability and enzyme activity levels. However, there was a highly significant correlation between the resistance, bio-mass parameters and enzyme activity levels.


Assuntos
Capsicum , Phytophthora , Capsicum/genética , Variação Genética , Fenilalanina Amônia-Liase/genética , Doenças das Plantas/genética
5.
Sci Rep ; 11(1): 16907, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413429

RESUMO

The Phytophtora root and stem rot is a serious disease in soybean. It is caused by the oomycete pathogen Phytophthora sojae. Growing Phytophthora resistant cultivars is the major method of controlling this disease. Resistance is race- or gene-specific; a single gene confers immunity against only a subset of the P. sojae isolates. Unfortunately, rapid evolution of new Phytophthora sojae virulent pathotypes limits the effectiveness of an Rps ("resistance to Phytophthora sojae") gene to 8-15 years. The current study was designed to investigate the effectiveness of Rps12 against a set of P. sojae isolates using recombinant inbred lines (RILs) that contain recombination break points in the Rps12 region. Our study revealed a unique Rps gene linked to the Rps12 locus. We named this novel gene as Rps13 that confers resistance against P. sojae isolate V13, which is virulent to recombinants that contains Rps12 but lack Rps13. The genetic distance between the two Rps genes is 4 cM. Our study revealed that two tightly linked functional Rps genes with distinct race-specificity provide broad-spectrum resistance in soybean. We report here the molecular markers for incorporating the broad-spectrum Phytophthora resistance conferred by the two Rps genes in commercial soybean cultivars.


Assuntos
Resistência à Doença/genética , Genes de Plantas , Phytophthora/fisiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Soja/genética , Soja/microbiologia , Alelos , Endogamia , Mapeamento Físico do Cromossomo , Phytophthora/isolamento & purificação , Proteínas de Plantas/metabolismo , Polimorfismo Genético
6.
Mol Ecol ; 30(20): 5164-5178, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34398981

RESUMO

Various hypotheses have been proposed regarding the origin of the plant pathogen Phytophthora cinnamomi. P. cinnamomi is a devastating, highly invasive soilborne pathogen associated with epidemics of agricultural, horticultural and forest plantations and native ecosystems worldwide. We conducted a phylogeographic analysis of populations of this pathogen sampled in Asia, Australia, Europe, southern and northern Africa, South America, and North America. Based on genotyping-by-sequencing, we observed the highest genotypic diversity in Taiwan and Vietnam, followed by Australia and South Africa. Mating type ratios were in equal proportions in Asia as expected for a sexual population. Simulations based on the index of association suggest a partially sexual, semi-clonal mode of reproduction for the Taiwanese and Vietnamese populations while populations outside of Asia are clonal. Ancestral area reconstruction provides new evidence supporting Taiwan as the ancestral area, given our sample, indicating that this region might be near or at the centre of origin for this pathogen as speculated previously. The Australian and South African populations appear to be a secondary centre of diversity following migration from Taiwan or Vietnam. Our work also identified two panglobal, clonal lineages PcG1-A2 and PcG2-A2 of A2 mating type found on all continents. Further surveys of natural forests across Southeast Asia are needed to definitively locate the actual centre of origin of this important plant pathogen.


Assuntos
Phytophthora , Austrália , Ecossistema , Especificidade de Hospedeiro , Filogeografia , Phytophthora/genética , Doenças das Plantas
7.
Chem Biodivers ; 18(9): e2100329, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34346150

RESUMO

Endeavor to discover biorational natural products-based fungicides, two series (26) of novel 1-sulfonyloxy/acyloxydihydroeugenol derivatives (3a-p and 5a-j) were prepared and assessed for their fungicidal activity against P. capsici Leonian, in vitro. Results of fungicidal activity revealed that, among all compounds, especially compounds 3a, 5c, and 5e displayed the most potent anti-oomycete activity against P. capsici with EC50 values of 69.33, 68.81, and 67.77 mg/L, respectively. Overall, the anti-oomycete activities of 1-acyloxydihydroeugenol derivatives (5a-j) were higher than that of 1-sulfonyloxydihydroeugenol derivatives (3a-p). It is proved that the introduction of the acyl group at hydroxy position of dihydroeugenol is more beneficial to improve its anti-oomycete activity than that of the sulfonyl group. These preliminary results will pave the way for further modification of dihydroeugenol in the development of potential new fungicides.


Assuntos
Produtos Biológicos/farmacologia , Eugenol/farmacologia , Fungicidas Industriais/farmacologia , Oomicetos/efeitos dos fármacos , Produtos Biológicos/síntese química , Produtos Biológicos/química , Eugenol/análogos & derivados , Eugenol/química , Fungicidas Industriais/síntese química , Fungicidas Industriais/química , Estrutura Molecular , Testes de Sensibilidade Parasitária , Phytophthora/efeitos dos fármacos
8.
Int J Mol Sci ; 22(12)2021 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-34202990

RESUMO

Proteins that contain the FYVE zinc-finger domain are recruited to PtdIns3P-containing membranes, participating in numerous biological processes such as membrane trafficking, cytoskeletal regulation, and receptor signaling. However, the genome-wide distribution, evolution, and biological functions of FYVE-containing proteins are rarely reported for oomycetes. By genome mining of Phytophthora sojae, two proteins (PsFP1 and PsFP2) with a combination of the FYVE domain and the PX domain (a major phosphoinositide binding module) were found. To clarify the functions of PsFP1 and PsFP2, the CRISPR/Cas9-mediated gene replacement system was used to knock out the two genes respectively. Only heterozygous deletion mutants of PsFP1 were recovered, and the expression level of PsFP1 in the heterozygous knockout transformants was significantly down-regulated. These PsFP1 mutants showed a decrease in mycelial growth and pathogenicity and were more sensitive to hydrogen peroxide. These phenotypes were recovered to the level of wild-type by overexpression PsFP1 gene in the PsFP1 heterozygous knockout transformant. In contrast, deletion of PsFP2 had no significant effect on vegetative growth, asexual and sexual reproduction, pathogenicity, or oxidative stress sensitivity. PsFP1 was primarily localized in vesicle-like structures and both the FYVE and PX domains are important for its localization. Overall, our results indicate that PsFP1 plays an important role in the vegetative growth and virulence of P. sojae.


Assuntos
Estresse Oxidativo , Phytophthora/fisiologia , Proteínas/metabolismo , Dedos de Zinco , Sequência de Aminoácidos , Expressão Gênica , Fenótipo , Phytophthora/patogenicidade , Doenças das Plantas/parasitologia , Domínios Proteicos , Transporte Proteico , Proteínas/química , Proteínas/genética , Deleção de Sequência , Virulência/genética
9.
J Exp Bot ; 72(15): 5751-5765, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34195821

RESUMO

Due to their sessile nature, plants must respond to various environmental assaults in a coordinated manner. The endoplasmic reticulum is a central hub for plant responses to various stresses. We previously showed that Phytophthora utilizes effector PsAvh262-mediated binding immunoglobulin protein (BiP) accumulation for suppressing endoplasmic reticulum stress-triggered cell death. As a BiP binding partner, Bcl-2-associated athanogene 7 (BAG7) plays a crucial role in the maintenance of the unfolded protein response, but little is known about its role in plant immunity. In this work, we reveal a double-faced role of BAG7 in Arabidopsis-Phytophthora interaction in which it regulates endoplasmic reticulum stress-mediated immunity oppositely in different cellular compartments. In detail, it acts as a susceptibility factor in the endoplasmic reticulum, but plays a resistance role in the nucleus against Phytophthora. Phytophthora infection triggers the endoplasmic reticulum-to-nucleus translocation of BAG7, the same as abiotic heat stress; however, this process can be prevented by PsAvh262-mediated BiP accumulation. Moreover, the immunoglobulin/albumin-binding domain in PsAvh262 is essential for both pathogen virulence and BiP accumulation. Taken together, our study uncovers a double-faced role of BAG7; Phytophthora advances its colonization in planta by utilizing an effector to detain BAG7 in the endoplasmic reticulum.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Phytophthora , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Estresse do Retículo Endoplasmático , Doenças das Plantas , Imunidade Vegetal/genética
10.
PLoS One ; 16(7): e0254645, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34260624

RESUMO

Phytophthora cinnamomi is a plant pathogenic oomycete that causes Phytophthora root rot of avocado (PRR). Currently, there is a limited understanding of the molecular interactions underlying this disease. Other Phytophthora species employ an arsenal of effector proteins to manipulate host physiology, of which the RxLR effectors contribute to virulence by interfering with host immune responses. The aim of this study was to identify candidate RxLR effectors in P. cinnamomi that play a role in establishing PRR, and to infer possible functions for these effectors. We identified 61 candidate RxLR genes which were expressed during infection of a susceptible avocado rootstock. Several of these genes were present in multiple copies in the P. cinnamomi genome, suggesting that they may contribute to pathogen fitness. Phylogenetic analysis of the manually predicted RxLR protein sequences revealed 12 P. cinnamomi RxLRs that were related to characterised effectors in other Phytophthora spp., providing clues to their functions in planta. Expression profiles of nine more RxLRs point to possible virulence roles in avocado-highlighting a way forward for studies of this interaction. This study represents the first investigation of the expression of P. cinnamomi RxLR genes during the course of avocado infection, and puts forward a pipeline to pinpoint effector genes with potential as virulence determinants, providing a foundation for the future functional characterization of RxLRs that contribute to P. cinnamomi virulence in avocado.


Assuntos
Persea/parasitologia , Phytophthora/patogenicidade , Filogenia , Virulência
11.
Phytochemistry ; 189: 112820, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34091112

RESUMO

Specialized metabolites are essential components in plant defence systems, serving as signalling molecules and chemical weapons against pathogens. The manipulation of plant defence metabolome or metabolites can thus be an important virulence strategy for pathogens. Because of their central role, metabolites can give valuable insights into plant-pathogen interactions. Here, we have conducted nontargeted metabolite profiling with UPLC-ESI-qTOF-MS to investigate the metabolic changes that have taken place in the crown tissue of Fragaria vesca L. (woodland strawberry) and Fragaria × ananassa (Weston) Duchesne ex Rozier (garden strawberry) during 48 h after Phytophthora cactorum challenge. Two P. cactorum isolates were compared: Pc407 is highly virulent to F. × ananassa and causes crown rot, whereas Pc440 is mildly virulent. In total, 45 metabolites differentially accumulated between the treatment groups were tentatively identified. Triterpenoids and various lipid compounds were highly represented. The levels of several triterpenoids increased upon inoculation, some of them showing distinct accumulation patterns in different interactions. Triterpenoids could either inhibit or stimulate P. cactorum growth and, therefore, triterpenoid profiles might have significant impact on disease progression. Of the lipid compounds, lysophospholipids, linoleic acid and linolenic acid were highly accumulated in the most compatible Pc407 - F. × ananassa interaction. As lysophospholipids promote cell death and have been linked to susceptibility, these compounds might be involved in the pathogenesis of crown rot disease. This metabolite analysis revealed potential factors contributing to the outcome of P. cactorum - strawberry interactions. The information is highly valuable, as it can help to find new breeding strategies and new solutions to control P. cactorum in strawberry.


Assuntos
Fragaria , Phytophthora , Lipídeos , Melhoramento Vegetal , Doenças das Plantas , Terpenos
12.
Molecules ; 26(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071493

RESUMO

In this study, the antifungal potential of chemical constituents from Piper pesaresanum and some synthesized derivatives was determined against three phytopathogenic fungi associated with the cocoa crop. The methodology included the phytochemical study on the aerial part of P. pesaresanum, the synthesis of some derivatives and the evaluation of the antifungal activity against the fungi Moniliophthora roreri, Fusarium solani and Phytophthora sp. The chemical study allowed the isolation of three benzoic acid derivatives (1-3), one dihydrochalcone (4) and a mixture of sterols (5-7). Seven derivatives (8-14) were synthesized from the main constituents, of which compounds 9, 10, 12 and 14 are reported for the first time. Benzoic acid derivatives showed strong antifungal activity against M. roreri, of which 11 (3.0 ± 0.8 µM) was the most active compound with an IC50 lower compared with positive control Mancozeb® (4.9 ± 0.4 µM). Dihydrochalcones and acid derivatives were active against F. solani and Phytophthora sp., of which 3 (32.5 ± 3.3 µM) and 4 (26.7 ± 5.3 µM) were the most active compounds, respectively. The preliminary structure-activity relationship allowed us to establish that prenylated chains and the carboxyl group are important in the antifungal activity of benzoic acid derivatives. Likewise, a positive influence of the carbonyl group on the antifungal activity for dihydrochalcones was deduced.


Assuntos
Antifúngicos/farmacologia , Cacau/metabolismo , Piper/metabolismo , Agaricales/metabolismo , Ácido Benzoico/química , Chalconas/química , Cromatografia , Fusarium/metabolismo , Concentração Inibidora 50 , Íons , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Compostos Fitoquímicos , Phytophthora/metabolismo , Relação Estrutura-Atividade
13.
Microbes Environ ; 36(2)2021.
Artigo em Inglês | MEDLINE | ID: mdl-34108359

RESUMO

Phytophthora species cause destructive plant diseases worldwide. All Phytophthora species, except for one, are listed as plant quarantine organisms in Japan. The exception, Phytophthora nicotianae is considered to be a domestic species. The injurious pests Phytophthora ramorum, Phytophthora lateralis, and Phytophthora kernoviae are invasive pathogens that cause tree mortality worldwide, mainly in the United States and the United Kingdom. To effectively control Phytophthora diseases, we established detection methods that utilize the loop-mediated isothermal amplification (LAMP) of the genus Phytophthora and the four species P. ramorum, P. lateralis, P. kernoviae, and P. nicotianae. LAMP primers for P. ramorum, P. lateralis, and P. kernoviae were newly designed in the present study. Our multiplex assay includes the detection of plant DNA as an internal control. When the optimum ratio between plant and pathogen primers was used in multiplex LAMP assays, 1 pg to 100 fg of pathogen DNA was detected with similar sensitivity to that in simplex LAMP assays. The detection of plant DNA in the absence of pathogens enables us to check for and avoid undesirable negative results caused by enzyme inactivation or the contamination of amplification inhibitors from plant tissues. The total time from sample collection to results is approximately 120| |min, and, thus, our multiplex LAMP assay may be used as an accurate and time-saving detection method for Phytophthora pathogens.


Assuntos
Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Phytophthora/isolamento & purificação , Doenças das Plantas/microbiologia , Primers do DNA/genética , Japão , Phytophthora/classificação , Phytophthora/genética , Doenças das Plantas/genética , Plantas/genética , Plantas/microbiologia
14.
Ecology ; 102(8): e03430, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34105778

RESUMO

Interactions among plant species and their soil biota drive plant-soil feedbacks (PSFs) that play a major role in the dynamics and diversity of plant communities. Among the different components of the soil community, pathogens are considered to be the main drivers of negative PSFs. Despite this, the number of studies that have experimentally quantified the contribution of soil pathogens to PSFs remains considerably low. Here we conducted a greenhouse experiment with oomycete-specific fungicide to quantify the contribution of soil pathogens, and particularly oomycete pathogens, to individual and pairwise PSFs in forest communities. We used as a case study Mediterranean mixed forests dominated by Quercus suber and invaded by the oomycete pathogen Phytophthora cinnamomi. The fungicide treatment was crossed with a competition treatment to explore how conspecific neighbors might modify pathogen effects. To place the results of the experiment in a wider context, we also conducted a systematic review of published papers that explicitly used fungicide to explore the role of pathogens in PSF experiments. Our experimental results showed that oomycete pathogens were the main drivers of individual PSFs in the study forests. Oomycete effects varied among tree species according to their susceptibility to P. cinnamomi, driving negative PSFs in the highly susceptible Q. suber but not in the coexistent Olea europaea. Oomycete-driven PSFs were not modified by intraspecific competition. Oomycete pathogens were also major contributors to negative pairwise PSFs assumed to promote species coexistence. Results from the systematic review supported the novelty of our experimental results, since only three studies had previously used oomycete-specific fungicide in a PSF context and none in systems invaded by exotic oomycetes. Overall, our results provide novel evidence of oomycete pathogens (including the exotic P. cinnamomi) as fundamental drivers of negative individual and pairwise PSFs with implications for species coexistence in invaded communities. Although in the short-term invasive pathogens might contribute to species coexistence by causing self-limitation in dominant species, strong inter-specific variation in self-limitation might undermine coexistence in the long-term. Because of the increasing number of exotic oomycetes worldwide, further attention should be given to oomycetes as drivers of PSFs in plant communities.


Assuntos
Phytophthora , Solo , Retroalimentação , Florestas , Plantas , Revisões Sistemáticas como Assunto
15.
Funct Plant Biol ; 48(10): 963-972, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34127178

RESUMO

Phytophthora spp. are the causal agents of gummosis or foot rot, fibrous root rot, and fruit brown rot diseases that affect the roots, trunk, and fruits of citrus trees, causing severe economic losses. This work presents an updated systematic review addressing the defence responses in citrus against Phytophthora and the strategies to manage Phytophthora diseases. Applying a new method of search based on an explicit, rigorous, and transparent methodology. For this purpose, a systematic literature review was conducted using the databases available for academic research. The main plant defence mechanisms reported in the cited papers are the hypersensitivity response, cell wall reinforcement, production of pathogenesis-related proteins, and expression of defence-related genes. Moreover, the main strategies to manage Phytophthora root rot are organic compounds in the soil and biological control with fungi and bacteria. In addition, inhibition of Phytophthora gummosis or canker by applying new oomycota fungicides and reducing the incidence of brown fruit rot through the application of potassium phosphite have also been reported. Moreover, modern plant biotechnology techniques can help to accelerate the selection of resistant rootstocks in breeding programs, as controlled crossings for the generation of hybrids, somatic hybridisation, transgenic citrus plants, mapped genomic regions of Quantitative Trait Loci (QTLs), candidate genes, metabolic markers and comparative transcriptomic. These innovative techniques represent a suitable tool to breed new Phytophthora resistant rootstocks, which is widely recognised as the best strategy to face gummosis or foot rot, fibrous root rot and ultimately minimise the expensive use of pesticides in crop protection.


Assuntos
Citrus , Fungicidas Industriais , Phytophthora , Melhoramento Vegetal , Doenças das Plantas
16.
J Hazard Mater ; 417: 126121, 2021 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-34020348

RESUMO

To understand the potential of urea-synthesized g-C3N4 nanosheets (0.125-1 mg/mL) as antimicrobial agents against oomycetes, an investigation of the interaction mechanism between g-C3N4 nanosheets and Phytophthora capsici was conducted. Transcription analysis showed that after being exposed to g-C3N4 nanosheets for 1 h, P. capsici triggered a sharp upregulation of antioxidant activities and structural constituents and a downregulation of metabolic pathways, including ATP generation, autophagy disruption, membrane system disorders and other complex adaptive processes. All the life stages of P. capsici, including mycelial growth, sporangium formation, zoospore numbers and zoospore germination were remarkably inhibited and even injured. A mutual mechanism is proposed in this work: ROS stress upon exposure to visible irradiation and, combined with their sharp nanosheet structure, cause perturbations of the cell membrane and induce damage to the ultrastructure of mycelial growth, sporangium and zoospores. Given that the antimicrobial action of g-C3N4 nanosheets were derived from the damage throughout the duration of treatment and was not limited to a single target, these complex mechanisms could favor the avoidance of drug resistance and benefit other oomycetes management. More importantly, in addition to restraining P. capsici infection in host plants, g-C3N4 nanosheets promoted pepper plant growth. Hence, g-C3N4 nanosheets have potential as a new non-metal antimicrobial agent to control oomycotal disease in crops.


Assuntos
Anti-Infecciosos , Phytophthora , Antibacterianos , Anti-Infecciosos/farmacologia , Plantas , Verduras
17.
PLoS One ; 16(5): e0250422, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34019564

RESUMO

Phytophthora agathidicida is associated with a root rot that threatens the long-term survival of the iconic New Zealand kauri. Although it is widely assumed that this pathogen arrived in New Zealand post-1945, this hypothesis has yet to be formally tested. Here we describe evolutionary analyses aimed at evaluating this and two alternative hypotheses. As a basis for our analyses, we assembled complete mitochondrial genome sequences from 16 accessions representing the geographic range of P. agathidicida as well as those of five other members of Phytophthora clade 5. All 21 mitogenome sequences were very similar, differing little in size with all sharing the same gene content and arrangement. We first examined the temporal origins of genetic diversity using a pair of calibration schemes. Both resulted in similar age estimates; specifically, a mean age of 303.0-304.4 years and 95% HPDs of 206.9-414.6 years for the most recent common ancestor of the included isolates. We then used phylogenetic tree building and network analyses to investigate the geographic distribution of the genetic diversity. Four geographically distinct genetic groups were recognised within P. agathidicida. Taken together the inferred age and geographic distribution of the sampled mitogenome diversity suggests that this pathogen diversified following arrival in New Zealand several hundred to several thousand years ago. This conclusion is consistent with the emergence of kauri dieback disease being a consequence of recent changes in the relationship between the pathogen, host, and environment rather than a post-1945 introduction of the causal pathogen into New Zealand.


Assuntos
Evolução Molecular , Genoma Mitocondrial , Phytophthora/genética , Doenças das Plantas/estatística & dados numéricos , Araucariaceae/microbiologia , Nova Zelândia , Phytophthora/patogenicidade , Doenças das Plantas/microbiologia , Polimorfismo Genético
18.
Fungal Biol ; 125(6): 477-484, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34024595

RESUMO

Analysis of soil samples using High Throughput Sequencing (HTS) frequently detects more Phytophthora species compared with traditional soil baiting methods. This study investigated whether differences between species in the timing and abundance of sporangial production and zoospore release could be a reason for the lower number of species isolated by baiting. Stems of Eucalyptus marginata were inoculated with ten Phytophthora species (P. nicotianae, P. multivora, P. pseudocryptogea, P. cinnamomi, P. thermophila, P. arenaria, P. heveae, P. constricta, P. gondwanensis and P. versiformis), and lesioned sections for each species were baited separately in water. There were significant differences between species in timing of sporangia production and zoospore release. P. nicotianae, P. pseudocryptogea, P. multivora and P. thermophila released zoospores within 8-12 h and could be isolated from lesioned baits within 1-2 days. In contrast, P. constricta did not produce zoospores for over 48 h and was only isolated 5-7 days after baiting. P. heveae and P. versiformis did not produce zoospores and were not recovered from the baits. When species were paired in the same baiting tub, those that produced zoospores in the shortest time were isolated most frequently, while species slow to produce zoospores, or which produced them in lower numbers, were isolated from few baits or not at all. Thus, species differences in the timing of sporangia production and zoospore release may contribute to the ease of isolation of some Phytophthora species when they are present together with other Phytophthora species in an environmental sample.


Assuntos
Phytophthora , Esporângios , Monitoramento Ambiental/métodos , Phytophthora/fisiologia , Esporângios/fisiologia , Fatores de Tempo
19.
Antonie Van Leeuwenhoek ; 114(8): 1165-1179, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33945066

RESUMO

Protection of crop plants from phytopathogens through endophytic bacteria is a newly emerged area of biocontrol. In this study, endophytic bacteria were isolated from the rhizosphere of Cannabis sativa. Based on initial antimicrobial screening, three (03) bacteria Serratia marcescens MOSEL-w2, Enterobacter cloacae MOSEL-w7, and Paenibacillus MOSEL-w13 were selected. Antimicrobial assays of these selected bacteria against Phytophthora parasitica revealed that E. cloacae MOSEL-w7 and Paenibacillus sp. MOSEL-w13 possessed strong activity against P. parasitica. All these bacterial extracts showed strong inhibition against P. parasitica at different concentrations (4-400 µg mL-1). P. parasitica hyphae treated with ethyl acetate extract of E. cloacae MOSEL-w7 resulted in severe growth abnormalities compared to control. The extracts were further evaluated for in vivo detached-leaf assay against P. parasitica on the wild type tobacco. Application of 1% ethyl acetate bacterial extract of S. marcescens MOSEL-w2, E. cloacae MOSEL-w7, and Paenibacillus sp. MOSEL-w13 reduced P. parasitica induced lesion sizes and lesion frequencies by 60-80%. HPLC based fractions of each extract also showed bioactivity against P. parasitica. A total of 24 compounds were found in the S. marcescens MOSEL-w2, 15 compounds in E. cloacae MOSEL-w7 and 20 compounds found in Paenibacillus sp. MOSEL-w13. LC-MS/MS analyses showed different bioactive compounds in the bacterial extracts such as Cotinine (alkylpyrrolidine), L-tryptophan, L-lysine, L-Dopa, and L-ornithine. These results suggest that S. marcescens MOSEL-w2, E. cloacae MOSEL-w7, and Paenibacillus MOSEL-w13 are a source of bioactive metabolites and could be used in combination with other biocontrol agents, with other modes of action for controlling diseases caused by Phytophthora in crops. They could be a clue for the broad-spectrum biopesticides for agriculturally significant crops.


Assuntos
Cannabis , Paenibacillus , Phytophthora , Cromatografia Líquida , Doenças das Plantas , Espectrometria de Massas em Tandem
20.
Mycologia ; 113(4): 734-747, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33974519

RESUMO

During an investigation of rivers in Bulgaria, an isolate of Phytophthora (RLKam2016/61c) was recovered and initially identified as Phytophthora sansomeana based on internal transcribed spacer region (ITS) sequence data. However, the sequencing of the mitochondrial cytochrome c oxidase subunit I (cox1) gene revealed high similarity to Phytophthora sp. kelmania, and sequencing of other nuclear regions (ß-tubulin [Btub] and translation elongation factor 1-alpha [tef1]) revealed a significant number of polymorphisms, indicating a possible hybridization event. Additional cloning and sequencing of the nuclear ITS and Btub regions showed the presence of two distinct groups of alleles, one of which was highly similar to P. sansomeana, whereas the other was similar to a species complex that includes Phytophthora sp. kelmania. Therefore, the new hybrid was named Phytophthora × sansomeana. It is characterized by fast growth on V8 juice agar (V8A) and carrot agar (CA), moderate aerial mycelium with radiate pattern of the colonies and relatively slower growth rate on malt extract agar (MEA) and potato dextrose agar (PDA), and petaloid to rosaceous pattern of the colonies with fluffy aerial mycelium. The optimum growth temperature for P. × sansomeana was at 25 C, with an average growth rate of 9 mm per day. Abundant sporangium formation of the isolate in spring water was observed, but the hybrid was sterile in culture. Pathogenicity analyses of the hybrid were conducted in comparison with the most closely related subclade 8a species from our collection, P. pseudocryptogea. The inhibition effect on the root growth of young seedlings of two legumes, common pea and vetch, as well as on cuttings of the ornamental plant coleus induced by both phytopathogens was significant. No effect of either the new hybrid or P. pseudocryptogea on the growth of maize seedlings was observed.


Assuntos
Phytophthora , Europa (Continente) , Filogenia , Phytophthora/genética , Plantas
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