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1.
Int J Mol Sci ; 22(19)2021 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-34638623

RESUMO

How herbivorous insects adapt to host plants is a key question in ecological and evolutionary biology. The fall armyworm, (FAW) Spodoptera frugiperda (J.E. Smith), although polyphagous and a major pest on various crops, has been reported to have a rice and corn (maize) feeding strain in its native range in the Americas. The species is highly invasive and has recently established in China. We compared behavioral changes in larvae and adults of a corn population (Corn) when selected on rice (Rice) and the molecular basis of these adaptational changes in midgut and antennae based on a comparative transcriptome analysis. Larvae of S. frugiperda reared on rice plants continuously for 20 generations exhibited strong feeding preference for with higher larval performance and pupal weight on rice than on maize plants. Similarly, females from the rice selected population laid significantly more eggs on rice as compared to females from maize population. The most highly expressed DEGs were shown in the midgut of Rice vs. Corn. A total of 6430 DEGs were identified between the populations mostly in genes related to digestion and detoxification. These results suggest that potential adaptations for feeding on rice crops, may contribute to the current rapid spread of fall armyworm on rice crops in China and potentially elsewhere. Consistently, highly expressed DEGs were also shown in antennae; a total of 5125 differentially expressed genes (DEGs) s were identified related to the expansions of major chemosensory genes family in Rice compared to the Corn feeding population. These results not only provide valuable insight into the molecular mechanisms in host plants adaptation of S. frugiperda but may provide new gene targets for the management of this pest.


Assuntos
Spodoptera/genética , Spodoptera/fisiologia , Adaptação Fisiológica/genética , Animais , China , Produtos Agrícolas/parasitologia , Fenômenos Fisiológicos do Sistema Digestório , Comportamento Alimentar/fisiologia , Feminino , Ontologia Genética , Genes de Insetos , Herbivoria/genética , Herbivoria/fisiologia , Adaptação ao Hospedeiro/genética , Adaptação ao Hospedeiro/fisiologia , Especificidade de Hospedeiro/genética , Especificidade de Hospedeiro/fisiologia , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Larva/fisiologia , Masculino , Oryza/parasitologia , Oviposição/fisiologia , Spodoptera/patogenicidade , Transcriptoma , Zea mays/parasitologia
2.
Sci Rep ; 11(1): 14770, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34285266

RESUMO

Pink stem borer (PSB) causes considerable yield losses to maize. Plant-insect interactions have significant implications for sustainable pest management. The present study demonstrated that PSB feeding, mechanical wounding, a combination of mechanical wounding and PSB regurgitation and exogenous application of methyl jasmonate have induced phenolic compound mediated defense responses both at short term (within 2 days of treatment) and long term (in 15 days of treatment) in leaf and stalk tissues of maize. The quantification of two major defense related phenolic compounds namely p-Coumaric acid (p-CA) and ferulic acid (FA) was carried out through ultra-fast liquid chromatography (UFLC) at 2 and 15 days after imposing the above treatments. The p-CA content induced in leaf tissues of maize genotypes were intrinsically higher when challenged by PSB attack at V3 and V6 stages in short- and long-term responses. Higher p-CA content was observed in stalk tissues upon wounding and regurgitation in short- and long-term responses at V3 and V6 stages. Significant accumulation of FA content was also observed in leaf tissues in response to PSB feeding at V3 stage in long-term response while at V6 stage it was observed both in short- and long-term responses. In stalk tissues, methyl jasmonate induced higher FA content in short-term response at V3 stage. However, at V6 stage PSB feeding induced FA accumulation in the short-term while, wounding and regurgitation treatment-induced defense responses in the long-term. In general, the resistant (DMRE 63, CM 500) and moderately resistant genotypes (WNZ ExoticPool) accumulated significantly higher contents of p-CA and FA content than susceptible ones (CM 202, BML 6) in most of the cases. The study indicates that phenolic mediated defense responses in maize are induced by PSB attack followed by wounding and regurgitation compared to the other induced treatments. Furthermore, the study confirmed that induced defense responses vary with plant genotype, stage of crop growth, plant tissue and short and long-term responses. The results of the study suggested that the Phenolic acids i.e. p-CA and FA may contribute to maize resistance mechanisms in the maize-PSB interaction system.


Assuntos
Acetatos/farmacologia , Ácidos Cumáricos/isolamento & purificação , Ciclopentanos/farmacologia , Mariposas/patogenicidade , Oxilipinas/farmacologia , Zea mays/crescimento & desenvolvimento , Animais , Parede Celular/química , Cromatografia Líquida , Resistência à Doença , Ácidos Graxos/química , Folhas de Planta/química , Zea mays/química , Zea mays/efeitos dos fármacos , Zea mays/parasitologia
3.
PLoS One ; 16(7): e0254328, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34252127

RESUMO

Fall armyworm (FAW; Spodoptera frugiperda), an exotic moth which recently invaded Africa, is a highly destructive pest of cereals especially maize a highly valued staple crop in Nigeria. The use of natural enemies such as predators or parasitoids for FAW control is more economically viable and environmentally safer than currently recommended synthetic insecticides. Natural enemies to combat the pest have not yet been reported in Nigeria. An exploration for the pests' natural enemies was undertaken by collecting FAW eggs and larvae from maize fields. These were reared in the laboratory for emergence, identification and efficacy as natural enemies. This yielded Euplectrus laphygmae (Hymenoptera: Eulophidae); Telenomus remus (Hymenoptera: Platygastridae) and Trombidium sp. (Acari.: Trombidiidae). Cotesia or Apanteles spp. were inferred to occur since Stictopisthus sp. (Hym.: Ichneumonidae), a secondary parasitoid, that attacks cocoons of Microgasterinae (e.g. Cotesia, Apanteles etc.) also emerged. Species of yet-to-be identified predators were also observed in various niches of maize plants. A positive relationship was found between FAW instar and the number of E. laphygmae eggs/instar ranging, on average, from 1.5 on second instar to 5.5 on fourth instars hosts. Parasitism rate of T. remus on FAW eggs was 100%. Parasitic mite infestation resulted in increasing paleness, reduced feeding, growth and movement as well as death of FAW 1st instars. Thus, the occurrence of FAW natural enemies in Nigeria calls for advocacy campaign to incorporate their use into integrated pest management strategies that attract and allow natural enemies to thrive for FAW management.


Assuntos
Spodoptera/fisiologia , Animais , Fazendas , Larva/fisiologia , Funções Verossimilhança , Nigéria , Óvulo/fisiologia , Parasitos/fisiologia , Filogenia , Comportamento Predatório/fisiologia , Zea mays/parasitologia
4.
Bull Entomol Res ; 111(5): 595-604, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33998414

RESUMO

With further climate change still expected, it is predicted to increase the frequency with plants will be water stressed, which subsequently influences phytophagous insects, particularly Lepidoptera with limited mobility of larvae. Previous studies have indicated that oviposition preference and offspring performance of Lepidoptera insects are sensitive to drought separately. However, the integration of their two properties is not always seen. Here, we evaluated changes in oviposition selection and offspring fitness of a Lepidoptera insect under three water-stressed treatments using a model agroecosystem consisting of maize Zea mays, and Asian corn borer Ostrinia furnacalis. Results found that female O. furnacalis preferred to laying their eggs on well-watered maize, and then their offspring tended to survive better, attained bigger larvae mass, and developed more pupae and adults on the preferred maize. Oviposition selection of O. furnacalis positively correlated with height and leaf traits of maize, and offspring fitness positively related with water content and phytochemical traits of hosts. Overall, these results suggest that oviposition choice performed by O. furnacalis reflects the maximization of offspring fitness, supporting preference-performance hypothesis. This finding further highlights that the importance of simultaneous evaluation of performance and performance for water driving forces should be involved, in order to accurately predict population size of O. furnacalis under altered precipitation pattern.


Assuntos
Comportamento de Escolha , Mariposas/fisiologia , Oviposição , Zea mays/parasitologia , Animais , Desidratação , Herbivoria , Mariposas/crescimento & desenvolvimento , Zea mays/fisiologia
6.
Sci Rep ; 11(1): 6797, 2021 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-33762675

RESUMO

Ultraviolet A (UV-A) radiation is a significant environmental factor that causes photoreceptor damage, apoptosis, and oxidative stress in insects. Ostrinia furnacalis is an important pest of corn. To understand the adaptation mechanisms of insect response to UV-A exposure, this study revealed differentially expressed genes (DEGs) and differently expressed metabolites (DEMs) in O. furnacalis under UV-A exposure. Three complementary DNA libraries were constructed from O. furnacalis adult females (CK, UV1h, and UV2h), and 50,106 expressed genes were obtained through Illumina sequencing. Of these, 157 and 637 DEGs were detected in UV1h and UV2h after UV-A exposure for 1 and 2 h, respectively, compared to CK, with 103 and 444 upregulated and 54 and 193 downregulated genes, respectively. Forty four DEGs were detected in UV2h compared to UV1h. Comparative transcriptome analysis between UV-treated and control groups revealed signal transduction, detoxification and stress response, immune defense, and antioxidative system involvement. Metabolomics analysis showed that 181 (UV1h vs. CK), 111 (UV2h vs. CK), and 34 (UV2h vs. UV1h) DEMs were obtained in positive ion mode, while 135 (UV1h vs. CK), 93 (UV2h vs. CK), and 36 (UV2h vs. UV1h) DEMs were obtained in negative ion mode. Moreover, UV-A exposure disturbed amino acid, sugar, and lipid metabolism. These findings provide insight for further studies on how insects protect themselves under UV-A stress.


Assuntos
Metaboloma/efeitos da radiação , Mariposas/metabolismo , Transcriptoma/efeitos da radiação , Raios Ultravioleta , Animais , Regulação para Baixo/efeitos da radiação , Feminino , Biblioteca Gênica , Mariposas/genética , Mariposas/efeitos da radiação , Estresse Oxidativo/genética , Análise de Componente Principal , Transdução de Sinais/genética , Fatores de Tempo , Regulação para Cima/efeitos da radiação , Zea mays/parasitologia
7.
BMC Plant Biol ; 21(1): 138, 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33726668

RESUMO

BACKGROUND: Maize (Zea mays L.) is a major cereal crop, with the United States accounting for over 40% of the worldwide production. Corn leaf aphid [CLA; Rhopalosiphum maidis (Fitch)] is an economically important pest of maize and several other monocot crops. In addition to feeding damage, CLA acts as a vector for viruses that cause devastating diseases in maize. We have shown previously that the maize inbred line Mp708, which was developed by classical plant breeding, provides heightened resistance to CLA. However, the transcriptomic variation conferring CLA resistance to Mp708 has not been investigated. RESULTS: In this study, we contrasted the defense responses of the resistant Mp708 genotype to those of the susceptible Tx601 genotype at the transcriptomic (mRNA-seq) and volatile blend levels. Our results suggest that there was a greater transcriptomic remodeling in Mp708 plants in response to CLA infestation compared to the Tx601 plants. These transcriptomic signatures indicated an activation of hormonal pathways, and regulation of sesquiterpenes and terpenoid synthases in a constitutive and inducible manner. Transcriptomic analysis also revealed that the resistant Mp708 genotype possessed distinct regulation of ethylene and jasmonic acid pathways before and after aphid infestation. Finally, our results also highlight the significance of constitutive production of volatile organic compounds (VOCs) in Mp708 and Tx601 plants that may contribute to maize direct and/or indirect defense responses. CONCLUSIONS: This study provided further insights to understand the role of defense signaling networks in Mp708's resistance to CLA.


Assuntos
Afídeos , Produtos Agrícolas/genética , Produtos Agrícolas/parasitologia , Perfilação da Expressão Gênica , Herbivoria , Zea mays/genética , Zea mays/parasitologia , Animais , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Estados Unidos
8.
Biochim Biophys Acta Gene Regul Mech ; 1864(3): 194687, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33561559

RESUMO

A dataset of gene expression from Spodoptera frugiperda, a highly generalist pest moth, was used to understand how gene regulation is related to larval host plant preference. Transcriptomic data of corn and rice strains of S. frugiperda larvae, reared on different diets, were analysed with three different approaches of gene network inference, namely co-expression, weighted co-expression and Bayesian networks, since each methodology provides a different visualization of the data. Using these approaches, it was possible to identify two loosely interconnected co-expression networks, one of them responsible for fast response to herbivory and anti-herbivory mechanisms and the other related to housekeeping genes, which present slower response to environmental variations. Integrating different levels of information such as gene expression patterns, gene assembly, transcriptomics, relationship among genes and phenotypes, functional relationships, among other information, enabled a wider visualization of S. frugiperda response to diet stimuli. The biological properties in the proposed networks are here described and discussed, as well as patterns of gene expression related to larval performance attributes.


Assuntos
Comportamento Alimentar/fisiologia , Regulação da Expressão Gênica/fisiologia , Oryza/parasitologia , Spodoptera/metabolismo , Transcriptoma/fisiologia , Zea mays/parasitologia , Animais , Perfilação da Expressão Gênica , Larva/genética , Larva/metabolismo , Spodoptera/genética
9.
Sci Rep ; 11(1): 2050, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479482

RESUMO

Genetic engineering (GM) has great potential to improve maize productivity, but rises some concerns on unintended effects, and equivalent as their comparators. There are some limitations through targeted analysis to detect the UE in genetically modified organisms in many previous studies. We here reported a case-study on the effects of introducing herbicides and insect resistance (HIR) gene cassette on molecular profiling (transcripts and metabolites) in a popular maize variety Zhengdan958 (ZD958) in China. We found that introducing HIR gene cassette bring a limited numbers of differential abundant genes (DAGs) or differential abundant metabolites (DAMs) between transgenic events and non-transgenic control. In contrast, averaged 10 times more DAGs and DAMs were observed when performed comparison under different growing environments in three different ecological regions of China than the numbers induced by gene effects. Major biological pathways relating to stress response or signaling transduction could explain somehow the effects of growing environments. We further compared two transgenic events mediated ZD958 (GM-ZD958) with either transgenic parent GM-Z58, and other genetic background nonGM-Z58, nonGM-ZD958, and Chang7-2. We found that the numbers of DAGs and DAMs between GM-ZD958 and its one parent maize variety, Z58 or GM-Z58 is equivalent, but not Chang7-2. These findings suggest that greater effects due to different genetic background on altered molecular profiling than gene modification itself. This study provides a case evidence indicating marginal effects of gene pleiotropic effects, and environmental effects should be emphasized.


Assuntos
Resistência a Herbicidas/genética , Plantas Geneticamente Modificadas/genética , Transcriptoma/genética , Zea mays/genética , Animais , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas/genética , Engenharia Genética , Herbicidas/efeitos adversos , Insetos/genética , Insetos/patogenicidade , Metabolômica , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/parasitologia , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
10.
Theor Appl Genet ; 134(3): 941-958, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33388884

RESUMO

KEY MESSAGE: Genome-wide association revealed that resistance to Striga hermonthica is influenced by multiple genomic regions with moderate effects. It is possible to increase genetic gains from selection for Striga resistance using genomic prediction. Striga hermonthica (Del.) Benth., commonly known as the purple witchweed or giant witchweed, is a serious problem for maize-dependent smallholder farmers in sub-Saharan Africa. Breeding for Striga resistance in maize is complicated due to limited genetic variation, complexity of resistance and challenges with phenotyping. This study was conducted to (i) evaluate a set of diverse tropical maize lines for their responses to Striga under artificial infestation in three environments in Kenya; (ii) detect quantitative trait loci associated with Striga resistance through genome-wide association study (GWAS); and (iii) evaluate the effectiveness of genomic prediction (GP) of Striga-related traits. An association mapping panel of 380 inbred lines was evaluated in three environments under artificial Striga infestation in replicated trials and genotyped with 278,810 single-nucleotide polymorphism (SNP) markers. Genotypic and genotype x environment variations were significant for measured traits associated with Striga resistance. Heritability estimates were moderate (0.42) to high (0.92) for measured traits. GWAS revealed 57 SNPs significantly associated with Striga resistance indicator traits and grain yield (GY) under artificial Striga infestation with low to moderate effect. A set of 32 candidate genes physically near the significant SNPs with roles in plant defense against biotic stresses were identified. GP with different cross-validations revealed that prediction of performance of lines in new environments is better than prediction of performance of new lines for all traits. Predictions across environments revealed high accuracy for all the traits, while inclusion of GWAS-detected SNPs led to slight increase in the accuracy. The item-based collaborative filtering approach that incorporates related traits evaluated in different environments to predict GY and Striga-related traits outperformed GP for Striga resistance indicator traits. The results demonstrated the polygenic nature of resistance to S. hermonthica, and that implementation of GP in Striga resistance breeding could potentially aid in increasing genetic gain for this important trait.


Assuntos
Resistência à Doença/genética , Melhoramento Vegetal , Doenças das Plantas/genética , Plantas Daninhas/fisiologia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Striga/fisiologia , Zea mays/genética , Alelos , Mapeamento Cromossômico/métodos , Cromossomos de Plantas/genética , Resistência à Doença/imunologia , Ligação Genética , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Doenças das Plantas/parasitologia , Zea mays/imunologia , Zea mays/parasitologia
11.
Trends Biotechnol ; 39(2): 105-107, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32713608

RESUMO

In late 2018, the highly destructive and polyphagous fall armyworm was first detected in China. It is now a major economic threat to corn production. In this article, the main control strategies that are available are reviewed and prospects to manage this pest with Bacillus thuringiensis (Bt) corn in China are discussed.


Assuntos
Controle de Pragas , Plantas Geneticamente Modificadas , Spodoptera , Animais , Bacillus thuringiensis/genética , Proteínas de Bactérias/genética , Biotecnologia , China , Endotoxinas/genética , Proteínas Hemolisinas/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Spodoptera/fisiologia , Zea mays/genética , Zea mays/parasitologia
12.
PLoS One ; 15(12): e0241530, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33332420

RESUMO

Maize, Zea mays L., is the most abundant field crop in China. Aphids are the most economically damaging pest on maize, particularly in the maize agri-ecosystems of Jilin Province, northeastern China. Parasitic wasps are important natural enemies of aphids, but limited information exists about their species composition, richness and seasonal dynamics in northeastern China. In this study, the population dynamics of maize aphids and parasitoid wasps were assessed in relation to each other during the summer seasons of two consecutive years, 2018 and 2019. We selected maize fields in the Changchun, Songyuan, Huinan and Gongzhuling areas of Jilin Province. Four species of aphids were recorded from these maize fields: Rhopalosiphum padi (L), Rhopalosiphum maidis (Fitch), Aphis gossypii Glover and Macrosiphum miscanthi (Takahashi). The dominant species in each of the four areas were R. maids (Filch) and R. padi in Changchun, R. padi in Songyuan, A. gossypii and R. padi in Huinan, and A.gossypii and R. padi in Gongzhuling. We delineated a species complex made up of primary parasitoids and hyperparasitoids associated with maize aphids. The primary parasitoids Lysiphlebus testaceipes, Binodoxys communis and Aphelinus albipodus together formed approximately 85.3% of the parasitoid complex. Pachyneuron aphidis, Phaenoglyphis villosa, Syrphophagus taeniatus and Asaphes suspensus made up the hyperparasitoids. Of the primary parasitoids, L. testaceipes was the dominant species (81.31%). Of the hyperparasitoid group, P. villosa was the dominant species (68.42%). Parasitism rates followed the fluctuation of the aphid population. The highest parasitic rate was observed during the peak period of cotton aphids. In this paper, the occurrence dynamics and dominant species of aphids and the dynamics of parasitic natural enemies of aphids in maize fields in Jilin Province are, for the first time, systematically reported. This study provides important information for the establishment and promotion of aphid biological control in maize fields.


Assuntos
Afídeos/parasitologia , Afídeos/patogenicidade , Vespas/patogenicidade , Zea mays/parasitologia , Animais , Afídeos/classificação , China , Ecossistema , Interações Hospedeiro-Parasita , Controle Biológico de Vetores , Dinâmica Populacional , Estações do Ano , Especificidade da Espécie , Vespas/classificação
13.
Int J Mol Sci ; 21(21)2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33153030

RESUMO

Ostrinia furnacalis, is the major pest of maize causing significant yield losses. So far, many approaches have been used to increase the virulence of entomopathogenic fungal isolates. The current study is an attempt to estimate synergistic effect of Beauveria bassiana and Trichoderma asperellum in order to explore larval immune response through RNA sequencing and differentially expression analysis. In vivo synergism was examined in seven proportions (B. bassiana: T. asperellum = 1:1, 1:2, 1:3, 1:4, 4:1, 3:1, 2:1) and in the in vitro case, two inoculation methods were applied: seed coating and soil drenching. Results revealed significant decrease in plant damage and high larval mortality in fungal treatments. Fungal isolates mediated the plant defense by increasing proline, superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO) and protease activities. Seed coating method was proved to be the most effective in case of maize endophytic colonization. In total, 59 immune-related differentially expressed genes DEGs were identified including, cytochrome P450, heat shock protein, ABC transporter, cadherin, peptidoglycan recognition protein (PGRP), cuticlular protein, etc. Further, transcriptomic response was confirmed by qRT-PCR. Our results concluded that, coculture of B. bassiana and T. asperellum has the synergistic potential to suppress the immune response of O. furnacalis and can be used as sustainable approach to induce plant resistance through activation of defense-related enzymes.


Assuntos
Beauveria/fisiologia , Hypocreales/fisiologia , Imunidade/fisiologia , Mariposas/imunologia , Zea mays/imunologia , Zea mays/parasitologia , Animais , Resistência à Doença/genética , Resistência à Doença/fisiologia , Perfilação da Expressão Gênica , Imunidade/genética , Larva/genética , Larva/imunologia , Larva/microbiologia , Mariposas/genética , Mariposas/microbiologia , Mariposas/patogenicidade , Controle Biológico de Vetores/métodos , Análise de Sequência de RNA , Transcriptoma , Zea mays/genética , Zea mays/microbiologia
14.
PLoS One ; 15(11): e0242791, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33253273

RESUMO

The Western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte is one of the most economically important insect pests in North America. Since 2003, transgenic maize expressing WCR-active proteins from Bacillus thuringiensis (Bt) have been widely adopted as the main approach to controlling WCR in the U.S. However, the emergence of field resistance to the Bt proteins in current commercial products has been documented in recent years, highlighting the need to develop additional tools for controlling this devasting pest. Here we report the discovery of Vpb4Da2 (initially assigned as Vip4Da2), a new insecticidal protein highly selective against WCR, through high-throughput genome sequencing of a Bt strain sourced from grain dust samples collected in the eastern and central regions of the US. Vpb4Da2 contains a sequence and domain signature distinct from families of other WCR-active proteins. Under field conditions, transgenic maize expressing Vpb4Da2 demonstrates commercial-level (at or below NIS 0.25) root protection against WCR, and reduces WCR beetle emergence by ≥ 97%. Our studies also conclude that Vpb4Da2 controls WCR populations that are resistant to WCR-active transgenic maize expressing Cry3Bb1, Cry34Ab1/Cry35Ab1 (reassigned as Gpp34Ab1/Tpp35Ab1), or DvSnf7 RNA. Based on these findings, Vpb4Da2 represents a valuable new tool for protecting maize against WCR.


Assuntos
Toxinas de Bacillus thuringiensis/genética , Besouros/genética , Controle Biológico de Vetores , Zea mays/genética , Animais , Bacillus thuringiensis/genética , Besouros/patogenicidade , Proteínas Hemolisinas/genética , Humanos , Resistência a Inseticidas/genética , Inseticidas/efeitos adversos , Inseticidas/química , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Zea mays/parasitologia
15.
Sci Rep ; 10(1): 16508, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-33020593

RESUMO

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a major pest native to the Americas. A recent invasion of FAWs from Africa eastward to South Asia, the Indochina Peninsula, and mainland China has received much attention due to the considerable economic losses in agriculture. FAWs can rapidly colonise a new area, likely due to the wide range of host plants, good flying capability, and high egg production. Therefore, a convenient, quick, and accurate tool for FAW identification is urgently required to establish a FAW invasion management strategy. In this study, FAW-specific primers were designed to recognise FAWs on the basis of internal transcribed spacer 1 (ITS1). The results revealed the accurate FAW recognition of the three congeneric species and eight common corn lepidopteran pests, especially at their larval stage. Furthermore, species-specific primers have confirmed their efficacy by using 69 FAW specimens from Taiwan, Thailand, and the United States, with a 96% success rate, excluding 3 decayed specimens. By using the simple, reliable, and convenient FAW-specific primers, a pest management programme can be developed not only to reduce sequencing costs and experimental time from 2 days to 4 h, but eradicate the FAW as soon as it enters a new area.


Assuntos
Reação em Cadeia da Polimerase Multiplex/métodos , Spodoptera/genética , Agricultura , Animais , Espécies Introduzidas , Larva , Controle de Pragas , Reação em Cadeia da Polimerase/métodos , Especificidade da Espécie , Spodoptera/patogenicidade , Zea mays/parasitologia
16.
PLoS One ; 15(10): e0234454, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33075073

RESUMO

Corn Stunt is an important disease in the Americas due to it high prevalence and the yield reductions that can cause when present. However, changes in the presence of this disease across years hampers the effective identification of resistant genotypes to this disease. To avoid the limitations of phenotypic selection under natural pressure, this research aimed to devise an effective strategy to screen disease-resistant genotypes in the absence of high and constant natural pressures. To do so, we investigated the presence of antixenosis and antibiosis as components of resistance to the vector Dalbulus maidis as well as resistance to the pathogen Spiroplasma kunkelii under artificial inoculation conditions in four maize hybrids. The hybrids shown differences in their levels of resistance and target organisms, either the insect vector or the pathogen. Antixenosis and antibiosis to D. maidis were observed in DK72-10. Resistance to S. kunkelii by DK79-10 was seen as a delayed onset of symptoms, and DKB390 showed antixenosis to D. maidis and resistance to S. kunkelii. An association between symptom severity and yield reduction was found, but not between accumulation of pathogen S. kunkelii and symptom severity nor yield. In conclusion, the proposed methodology was efficacious and can aid in the screening of resistant genotypes in breeding programs to reduce the impact of Corn Stunt disease, ensuring that hybrids with good resistance level will be planted by farmers whenever disease occurs.


Assuntos
Resistência à Doença , Hemípteros/microbiologia , Zea mays/crescimento & desenvolvimento , Animais , Antibiose , Feminino , Insetos Vetores/microbiologia , Melhoramento Vegetal , Spiroplasma , Zea mays/genética , Zea mays/parasitologia
17.
PLoS One ; 15(9): e0238523, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32911522

RESUMO

Brazil and South Africa, countries with economies in transition, are characterized by a dual agrarian structure co-occurring, sometimes, alongside in the same region. Large-scale commercial farming produces crops for export to global markets on the one hand, and small-scale farming, on the other hand, provides for subsistence and local markets. In both systems, maize (Zea mays) is a key crop for these two countries. For the commercial system, maize is a commodity crop while for the small-scale system it is the prime staple crop. In commercial systems, farmers predominantly grow genetically modified (GM) hybrid maize. In small-scale systems, farmers rely on open pollinated varieties (OPVs) and/or landraces and are largely dependent on seed saving systems. The aim of this study was to understand the relationship between transgene expression rates, the resulting concentrations of the transgene product (Bt protein) and its bioactivity in insect pests following transgene flow from GM hybrid maize into non-genetically modified, non-GM near-isogenic maize hybrid (ISO) and OPVs. We modeled segregation patterns and measured cry1Ab transgene expression (mRNA quantification), Cry1Ab protein concentration and pest survival. Two groups of F1, F2 crosses and backcrosses with GM, ISO and OPV maize varieties from Brazil and South Africa were used. Bioassays with the larvae of two lepidopteran maize pest species, Helicoverpa armigera and Spodoptera littoralis, were carried out. Overall, the cry1Ab transgene outcrossed effectively into the genetic backgrounds tested. The cry1Ab transgene was stably expressed in both ISO and OPV genetic backgrounds. Transgene introgression led to consistent, though highly variable, concentrations of Cry1Ab toxins that were similar to those observed in GM parental maize. Most crosses, but not all, suggested the expected Mendelian segregation pattern. Transgene expression rates were significantly higher than expected from purely Mendelian segregation in the South African crosses. In South African materials, ISO and OPV crosses produced significantly lower Cry1Ab concentrations compared to the GM parental maize. The Cry1Ab toxins from crosses were bioactive and induced mortality rates of ≥92.19% in H. armigera and ≥40.63% in S. littoralis after a period of only 4 days. However, no correlations were observed between the quantitation of mRNA for cry1Ab and the corresponding Cry1Ab protein concentrations, nor between the Cry1Ab concentrations and insect mortality rates across different genetic backgrounds. We therefore suggest that while transcription of the cry1Ab transgene reliably determines the presence of Cry1Ab protein, mRNA levels do not reflect, by themselves, the end Cry1Ab protein concentrations found in the plant. Because predictably high Cry1Ab concentrations are a key prerequisite for effective insect resistance management (IRM) programs, this observation raises questions about the effectiveness of such programs in scenarios with complex crop genetic backgrounds. On the other hand, confirmed bioactivity in all crosses should be expected to impact small farmer's selection behavior, unknowingly favoring the insecticidal trait. This may lead to a fixation of the trait in the wider population, and may influence the genetic diversity of varieties maintained by small-scale farmers.


Assuntos
Proteínas de Bactérias/genética , Endotoxinas/genética , Proteínas Hemolisinas/genética , Controle Biológico de Vetores , Plantas Geneticamente Modificadas/genética , Zea mays/genética , Animais , Toxinas de Bacillus thuringiensis , Produtos Agrícolas/genética , Cruzamentos Genéticos , Resistência à Doença , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Plantas Geneticamente Modificadas/parasitologia , Spodoptera/fisiologia , Transgenes , Zea mays/parasitologia
18.
Int J Mol Sci ; 21(17)2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32878074

RESUMO

Thioredoxins (Trxs) and thioredoxin reductases (TrxRs) encompass a highly complex network involved in sustaining thiol-based redox homeostasis in plant tissues. The purpose of the study was to gain a new insight into transcriptional reprogramming of the several genes involved in functioning of Trx/TrxR system in maize (Zea mays L.) seedlings, exposed to the bird cherry-oat aphid (Rhopalosiphum padi L.) or the rose-grass aphid (Metopolophium dirhodum Walk.) infestation. The biotests were performed on two maize genotypes (susceptible Zlota Karlowa and relatively resistant Waza). The application of real-time qRT-PCR technique allowed to identify a molecular mechanism triggered in more resistant maize plants, linked to upregulation of thioredoxins-encoding genes (Trx-f, Trx-h, Trx-m, Trx-x) and thioredoxin reductase genes (Ftr1, Trxr2). Significant enhancement of TrxR activity in aphid-infested Waza seedlings was also demonstrated. Furthermore, we used an electrical penetration graph (EPG) recordings of M. dirhodum stylet activities in seedlings of the two studied maize varieties. Duration of phloem phase (E1 and E2 models) of rose-grass aphids was about three times longer while feeding in Waza plants, compared to Zlota Karlowa cv. The role of activation of Trx/TrxR system in maintaining redox balance and counteracting oxidative-induced damages of macromolecules in aphid-stressed maize plants is discussed.


Assuntos
Afídeos/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/metabolismo , Plântula/metabolismo , Tiorredoxina Dissulfeto Redutase/metabolismo , Tiorredoxinas/metabolismo , Zea mays/metabolismo , Animais , Oxirredução , Doenças das Plantas/parasitologia , Proteínas de Plantas/genética , Plântula/genética , Plântula/parasitologia , Tiorredoxina Dissulfeto Redutase/genética , Zea mays/genética , Zea mays/parasitologia
19.
Sci Rep ; 10(1): 11205, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32641801

RESUMO

Tritrophic interactions allow plants to recruit natural enemies for protection against herbivory. Here we investigated genetic variability in induced responses to stemborer egg-laying in maize Zea mays (L.) (Poaceae). We conducted a genome wide association study (GWAS) of 146 maize genotypes comprising of landraces, inbred lines and commercial hybrids. Plants were phenotyped in bioassays measuring parasitic wasp Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) attraction to volatiles collected from plants exposed to stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) eggs. Genotyping-by-sequencing was used to generate maize germplasm SNP data for GWAS. The egg-induced parasitoid attraction trait was more common in landraces than in improved inbred lines and hybrids. GWAS identified 101 marker-trait associations (MTAs), some of which were adjacent to genes involved in the JA-defence pathway (opr7, aos1, 2, 3), terpene biosynthesis (fps3, tps2, 3, 4, 5, 7, 9, 10), benzoxazinone synthesis (bx7, 9) and known resistance genes (e.g. maize insect resistance 1, mir1). Intriguingly, there was also association with a transmembrane protein kinase that may function as a receptor for the egg elicitor and other genes implicated in early plant defence signalling. We report maize genomic regions associated with indirect defence and provide a valuable resource for future studies of tritrophic interactions in maize. The markers identified may facilitate selection of indirect defence by maize breeders.


Assuntos
Mariposas/anatomia & histologia , Defesa das Plantas contra Herbivoria/genética , Compostos Orgânicos Voláteis/metabolismo , Vespas/fisiologia , Zea mays/fisiologia , Animais , Ciclopentanos/metabolismo , Estudo de Associação Genômica Ampla , Herbivoria/fisiologia , Mariposas/parasitologia , Mariposas/fisiologia , Oviposição , Oxilipinas/metabolismo , Sementes/genética , Sementes/metabolismo , Zea mays/parasitologia
20.
Genes (Basel) ; 11(6)2020 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-32599710

RESUMO

Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology's single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAW and MW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10-30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and differentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.


Assuntos
Resistência à Doença/genética , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas/genética , Zea mays/genética , Animais , Mapeamento Cromossômico , Genômica , Genótipo , Controle de Pragas , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Polimorfismo de Nucleotídeo Único/genética , Gorgulhos/genética , Gorgulhos/patogenicidade , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
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