ABSTRACT
Abstract Bacterial leaf blight (BLB) is one of the major rice diseases in Malaysia. This disease causes substantial yield loss as high as 70%. Development of rice varieties which inherited BLB resistant traits is a crucial approach to promote and sustain rice industry in Malaysia. Hence, this study aims were to enhance BLB disease resistant characters of high yielding commercial variety MR219 through backcross breeding approach with supporting tool of marker-assisted selection (MAS). Broad spectrum BLB resistance gene, Xa7 from donor parent IRBB7 were introgressed into the susceptible MR219 (recurrent parent) using two flanking markers ID7 and ID15. At BC3F4, we managed to generate 19 introgressed lines with homozygous Xa7 gene and showed resistant characteristics as donor parent when it was challenged with Xanthomonas oryzae pv. oryzae through artificial inoculation. Recurrent parent MR219 and control variety, MR263 were found to be severely infected by the disease. The improved lines exhibited similar morphological and yield performance characters as to the elite variety, MR219. Two lines, PB-2-107 and PB-2-34 were chosen to be potential lines because of their outstanding performances compared to parent, MR219. This study demonstrates a success story of MAS application in development of improved disease resistance lines of rice against BLB disease.
Resumo A mancha bacteriana das folhas (BLB) é uma das principais doenças do arroz na Malásia. Essa doença causa perdas substanciais de rendimento de até 70%. O desenvolvimento de variedades de arroz que herdaram características de resistência ao BLB é uma abordagem crucial para promover e sustentar a indústria do arroz na Malásia. Portanto, o objetivo deste estudo foi aumentar os caracteres BLB resistentes a doenças da variedade comercial MR219 de alto rendimento por meio de uma abordagem de cruzamento retrocruzamento com ferramenta de apoio de seleção assistida por marcador (MAS). O gene de resistência a BLB de amplo espectro, Xa7 do pai doador IRBB7, foi introgressado no MR219 suscetível (pai recorrente) usando dois marcadores flanqueadores ID7 e ID15. No BC3F4, conseguimos gerar 19 linhagens introgressadas com o gene Xa7 homozigoto e apresentamos características de resistência como genitor doador quando desafiado com Xanthomonas oryzae pv. oryzae por inoculação artificial. O pai recorrente MR219 e a variedade controle, MR263, estavam gravemente infectados pela doença. As linhas melhoradas exibiram características morfológicas e de desempenho de rendimento semelhantes às da variedade elite, MR219. Duas linhas, PB-2-107 e PB-2-34, foram escolhidas como linhas potenciais por causa de seus desempenhos excelentes em comparação com a mãe, MR219. Este estudo demonstra uma história de sucesso de aplicação de MAS no desenvolvimento de linhas de arroz melhoradas com resistência a doenças contra a doença BLB.
Subject(s)
Oryza , Xanthomonas , Plant Diseases/genetics , Disease Resistance/genetics , Plant BreedingABSTRACT
Abstract Field survey study was conducted season (2017). Soybeans and weeds were weekly sampled randomly. Thrips adults were identified and counted. Detection of the virus isolate and the natural incidence was determined using; Mechanical transmission, host range, DAS-ELISA, RT-PCR. The natural incidence thrips individuals was detected depending on the SVNV% in thrips individuals and weeds hosts. Ten thrips species were associated with soybean plants in the field. The most abundant species was T. tabaci, average 256.5 average no.of individuals, followed by F. occidentalis (142.5 average no. of individuals), then N. variabilis (86.6/ average no. of individuals). Fourteen thrips species occurred on 5 legumes field crops and 41 weed plant species within soybean field. The highest average number 40.6.of individuals were recorded on Ammi majus. While the lowest one 3.3 average no. of individuals were on Urtica urens. Only 21diagnostic plant species were susceptible to infection with SVNV. G. max and Vigna radiate, were the highest percentage of infection 80% followed by V. unguilata & N. benthamiana, 75%. Egyptian isolate of Soybean vein necrosis virus (SVNV) in this study showed a high degree of similarity and it is closely related to TSWV from Egypt (DQ479968) and TCSV from USA (KY820965) with nucleotide sequence identity of 78%. Four thrips species transmitted SVNV (F. fusca 4.0%, F. schultzei 4.3%, F. tritici 3.3% and N. variabilis 68.0% transmission). Both C. phaseoli and M. sjostedti can acquire the virus but unable to transmit it. The following species; T. tabaci, F. occidentalis, S. dorsallis and T. palmi cannot acquire or transmit SVNV. The incidence of SVNV in the field started by the end of July then increased gradualy from 12.7 to 71.3% by the end of the season. In conclusion, few thrips individuals invaded soybean crops are enough to transmit high rate of SVNV within the crop. Furthermore, several vector species are also abundant on weeds, which are the major sources of soybean viruses transmitted to the crops. This information might be important for control and reduce the incidence of SVNV infection.
Resumo O estudo de pesquisa de campo foi realizado na temporada (2017). A soja e as ervas daninhas foram amostradas semanalmente de forma aleatória. Tripes adultos foram identificados e contados. A detecção do vírus isolado e a incidência natural foram determinadas usando transmissão mecânica, gama de hospedeiros, DAS-ELISA, RT-PCR. A incidência natural de tripes em indivíduos foi detectada dependendo da % de SVNV em tripes e hospedeiros infestantes. Dez espécies de tripes foram associadas a plantas de soja no campo. A espécie mais abundante foi T. tabaci, com média de 256,5 número médio de indivíduos, seguida por F. occidentalis (142,5) e N. variabilis (86,6 / número médio de indivíduos). Catorze espécies de tripes ocorreram em 5 culturas de leguminosas e 41 espécies de plantas daninhas dentro de campos de soja. O maior número médio de 40,6 indivíduos foi registrado em Ammi majus. Enquanto o mais baixo, 3,3 número médio de indivíduos, foi no Urtica urens. Apenas 21 espécies de plantas diagnosticadas foram suscetíveis à infecção com SVNV. G. max e Vigna radiate foram os maiores percentuais de infecção, 80%, seguidos por V. unguilata e N. benthamiana, 75%. O isolado egípcio neste estudo mostrou um alto grau de similaridade e está intimamente relacionado ao TSWV do Egito (DQ479968) e ao TCSV dos EUA (KY820965), com identidade de sequência de nucleotídeos de 78%. Quatro espécies de tripes transmitiram SVNV (F. fusca 4,0%, F. schultzei 4,3%, F. tritici 3,3% e N. variabilis 68,0% de transmissão). Tanto C. phaseoli quanto M. sjostedti podem adquirir o vírus, mas não podem transmiti-lo. As seguintes espécies, T. tabaci, F. occidentalis, S. dorsallis e T. palmi não podem adquirir ou transmitir SVNV. A incidência de SVNV no campo, iniciada no final de julho, aumentou gradativamente de 12,7 para 71,3% no final da temporada. Em conclusão, poucos indivíduos de tripes invadiram a cultura da soja e são suficientes para transmitir alta taxa de SVNV dentro da cultura. Além disso, várias espécies de vetores também abundam em ervas daninhas, que são as principais fontes dos vírus da soja transmitidos às lavouras. Essas informações podem ser importantes para controlar e reduzir a incidência de infecção por SVNV.
Subject(s)
Humans , Tospovirus , Plant Diseases , Soybeans , Incidence , Urticaceae , Egypt/epidemiology , Plant Weeds , NecrosisABSTRACT
Abstract Cucumber mosaic virus (CMV) is a tremendous threat to vegetables across the globe, including in Pakistan. The present work was conducted to investigate the genetic variability of CMV isolates infecting pea and spinach vegetables in the Pothwar region of Pakistan. Serological-based surveys during 2016-2017 revealed 31.70% overall CMV disease incidence from pea and spinach crops. Triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) revealed that all the positive isolates belong to CMV subgroup II. Two selected cDNA from ELISA-positive samples representing each pea and spinach crops were PCR-amplified (ca.1100 bp) and sequenced corresponding to the CMV CP gene which shared 93.7% nucleotide identity with each other. Both the sequences of CMV pea (AAHAP) and spinach (AARS) isolates from Pakistan were submitted to GenBank as accession nos. MH119071 and MH119073, respectively. BLAST analysis revealed 93.4% sequence identity of AAHAP isolate with SpK (KC763473) from Iran while AARS isolate shared maximum identity (94.5%) with the strain 241 (AJ585519) from Australia and clustered with some reference isolates of CMV subgroup II from UK (Z12818) and USA (AF127976) in a Neighbour-joining phylogenetic reconstruction. A total of 59 polymorphic (segregating) sites (S) with nucleotide diversity (π) of 0.06218 was evident while no INDEL event was observed in Pakistani isolates. The evolutionary distance of Pakistani CMV isolates was recorded as 0.0657 with each other and 0.0574-0.2964 with other CMV isolates reported elsewhere in the world. A frequent gene flow (Fst = 0.30478 <0.33) was observed between Pakistani and earlier reported CMV isolates. In genetic differentiation analysis, the value of three permutation-based statistical tests viz; Z (84.3011), Snn (0.82456), and Ks* (4.04042) were non-significant. The statistical analysis revealed the values 2.02535, 0.01468, and 0.71862 of Tajima's D, Fu, & Li's F* and D* respectively, demonstrating that the CMV population is under balancing selection.
Resumo Cucumber mosaic cucumovirus (CMV) é uma tremenda ameaça aos vegetais em todo o mundo, inclusive no Paquistão. O presente trabalho foi conduzido para investigar a variabilidade genética de isolados de CMV infectando vegetais de ervilha e espinafre na região de Pothwar, Paquistão. Pesquisas com base em sorologia durante 2016-2017 revelaram 31,70% da incidência geral da doença por CMV em safras de ervilha e espinafre. O ensaio de imunoabsorção enzimática em sanduíche de anticorpo triplo (TAS-ELISA) revelou que todos os isolados positivos pertencem ao subgrupo II do CMV. Dois cDNA selecionados de amostras positivas para ELISA representando cada safra de ervilha e espinafre foram amplificados por PCR (ca.1100 pb) e sequenciados correspondendo ao gene CMV CP que compartilhou 93,7% de identidade de nucleotídeo um com o outro. Ambas as sequências de isolados de ervilha CMV (AAHAP) e espinafre (AARS) do Paquistão foram submetidas ao GenBank como nos de acesso. MH119071 e MH119073, respectivamente. A análise BLAST revelou 93,4% de identidade de sequência do isolado AAHAP com SpK (KC763473) do Irã, enquanto o isolado AARS compartilhou a identidade máxima (94,5%) com a cepa 241 (AJ585519) da Austrália e agrupada com alguns isolados de referência do subgrupo II de CMV do Reino Unido (Z12818) e EUA (AF127976) em uma reconstrução filogenética vizinha. Um total de 59 sítios polimórficos (segregantes) (S) com diversidade de nucleotídeos (π) de 0,06218 foi evidente, enquanto nenhum evento INDEL foi observado em isolados do Paquistão. A distância evolutiva de isolados de CMV do Paquistão foi registrada como 0,0657 entre si e 0,0574-0,2964 com outros isolados de CMV relatados em outras partes do mundo. Um fluxo gênico frequente (Fst = 0,30478 < 0,33) foi observado entre os isolados de CMV do Paquistão e relatados anteriormente. Na análise de diferenciação genética, os valores de três testes estatísticos baseados em permutação viz, Z (84,3011), Snn (0,82456) e Ks * (4,04042) não foram significativos. A análise estatística revelou os valores 2,02535, 0,01468 e 0,71862 de Tajima's D, Fu, & Li's F * e D * respectivamente, demonstrando que a população de CMV está sob seleção de balanceamento.
Subject(s)
Cucumovirus/genetics , Cucumis sativus , Pakistan , Phylogeny , Plant Diseases , Genetic Variation , Spinacia oleracea , PeasABSTRACT
Abstract Utilization of modern breeding techniques for developing high yielding and uniform plant types ultimately narrowing the genetic makeup of most crops. Narrowed genetic makeup of these crops has made them vulnerable towards disease and insect epidemics. For sustainable crop production, genetic variability of these crops must be broadened against various biotic and abiotic stresses. One of the ways to widen genetic configuration of these crops is to identify novel additional sources of durable resistance. In this regard crops wild relatives are providing valuable sources of allelic diversity towards various biotic, abiotic stress tolerance and quality components. For incorporating novel variability from wild relative's wide hybridization technique has become a promising breeding method. For this purpose, wheat-Th. bessarabicum amphiploid, addition and translocation lines have been screened in field and screen house conditions to get novel sources of yellow rust and Karnal bunt resistant. Stripe rust screening under field conditions has revealed addition lines 4JJ and 6JJ as resistant to moderately resistant while addition lines 3JJ, 5JJ, 7JJ and translocation lines Tr-3, Tr-6 as moderately resistant wheat-Thinopyrum-bessarabicum genetic stock. Karnal bunt screening depicted addition lines 5JJ and 4JJ as highly resistant genetic stock. These genetic stocks may be used to introgression novel stripe rust and Karnal bunt resistance from the tertiary gene pool into susceptible wheat backgrounds.
Resumo A utilização de técnicas modernas de melhoramento para o desenvolvimento de tipos de plantas uniformes e de alto rendimento, em última análise, estreitando a composição genética da maioria das culturas. A composição genética restrita dessas plantações tornou-as vulneráveis a doenças e epidemias de insetos. Para uma produção agrícola sustentável, a variabilidade genética dessas culturas deve ser ampliada contra vários estresses bióticos e abióticos. Uma das maneiras de ampliar a configuração genética dessas culturas é identificar novas fontes adicionais de resistência durável. A esse respeito, os parentes selvagens das culturas estão fornecendo fontes valiosas de diversidade alélica para vários componentes de qualidade e tolerância ao estresse abiótico e biótico. Para incorporar a nova variabilidade da ampla técnica de hibridização de parente selvagem tornou-se um método de reprodução promissor. Para esse efeito, trigo-Th. As linhas anfiploides, de adição e translocação de bessarabicum foram selecionadas em condições de campo e de casa de tela para obter novas fontes de ferrugem amarela e resistência ao bunt de Karnal. A triagem de ferrugem em faixas em condições de campo revelou as linhas de adição 4JJ e 6JJ como resistentes a moderadamente resistentes, enquanto as linhas de adição 3JJ, 5JJ, 7JJ e as linhas de translocação Tr-3, Tr-6 como estoque genético de trigo-Thinopyrum bessarabicum moderadamente resistente. A triagem Karnal bunt descreveu as linhas de adição 5JJ e 4JJ como estoque genético altamente resistente. Esses estoques genéticos podem ser usados para introgressão da nova ferrugem e resistência ao bunt de Karnal do pool genético terciário em origens de trigo suscetíveis.
Subject(s)
Basidiomycota/genetics , Triticum/genetics , Plant Diseases/genetics , Chromosomes, Plant , Disease Resistance/genetics , Plant BreedingABSTRACT
In this study, a new Bacillus velezensis strain Bv-303 was identified and its biocontrol effect against rice bacterial-blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) was investigated. Cell-free supernatant (CFS) of strain Bv-303 under different growth conditions were prepared to test the antagonistic activity and stability against Xoo by the Oxford-cup method in vitro. The antibacterial effect of strain Bv-303 to BB disease in rice were further analyzed in vivo by spraying the cell-culture broth (CCB), CFS and cell-suspension water (CSW), respectively, on the rice leaves inoculated with Xoo. Additionally, rice seeds germination rate and seedling growth under the strain Bv-303 CCB treatment were tested. The results showed that the strain Bv-303 CFS significantly inhibited Xoo growth by 85.7%‒88.0% in vitro, which was also stable under extreme environment conditions such as heat, acid, alkali and ultraviolet light. As tested in vivo, spraying the CCB, CFS or CSW of strain Bv-303 on the Xoo-infected leaves enhanced rice plant resistance to BB disease, with CCB showing the highest increase (62.7%) in disease-resistance. Notably, CCB does not have negative effects on rice seed germination and seedling growth. Therefore, strain Bv-303 has great potential for biocontrol of the rice BB disease.
Subject(s)
Oryza , Fatigue Syndrome, Chronic , Bacillus , Xanthomonas , Plant Diseases/microbiologyABSTRACT
Abstract Endophytic bacteria serve key roles in the maintenance of plant health and growth. Few studies to date, however, have explored the antagonistic and plant growth-promoting (PGP) properties of Prunus cerasifera endophytes. To that end, we isolated endophytic bacteria from P. cerasifera tissue samples and used a dual culture plate assay to screen these microbes for antagonistic activity against Verticillium dahliae, Botryosphaeria dothidea, Fusarium oxysporum, F. graminearum, and F. moniliforme. Of the 36 strains of isolated bacteria, four (strains P1, P10, P16, and P20) exhibited antagonistic effects against all five model pathogens, and the P10 strain exhibited the strongest antagonistic to five pathogens. This P10 strain was then characterized in-depth via phenotypic assessments, physiological analyses, and 16s rDNA sequencing, revealing it to be a strain of Bacillus subtilis. Application of a P10 cell suspension (1×108 CFU/mL) significantly enhanced the seed germination and seedling growth of tomato in a greenhouse setting. This P10 strain further significantly suppressed tomato Verticillium wilt with much lower disease incidence and disease index scores being observed following P10 treatment relative to untreated plants in pot-based experiments. Tomato plants that had been treated with strain P10 also enhanced defense-related enzymes, peroxidase, superoxide dismutase, and catalase activity upon V. dahliae challenge relative to plants that had not been treated with this endophytic bacterium. The results revealed that the P10 bacterial strain has potential value as a biocontrol agent for use in the prevention of tomato Verticillium wilt.
Resumo As bactérias endofíticas desempenham papel fundamental na manutenção da saúde e do crescimento das plantas. Poucos estudos até o momento, no entanto, exploraram as propriedades antagônicas e promotoras de crescimento de plantas (PGP) de endófitos de Prunus cerasifera. Para esse fim, isolamos bactérias endofíticas de amostras de tecido de P. cerasifera e usamos um ensaio de placa de cultura dupla para rastrear esses micróbios quanto à atividade antagonista contra Verticillium dahliae, Botryosphaeria dothidea, Fusarium oxysporum, F. graminearum e F. moniliforme. Das 36 cepas de bactérias isoladas, quatro (cepas P1, P10, P16 e P20) exibiram efeitos antagônicos contra todos os cinco patógenos modelo, e a cepa P10 exibiu o antagonista mais forte para cinco patógenos. Essa cepa P10 foi então caracterizada em profundidade por meio de avaliações fenotípicas, análises fisiológicas e sequenciamento de rDNA 16s, revelando ser uma cepa de Bacillus subtilis. A aplicação de uma suspensão de células P10 (1 × 108 UFC / mL) aumentou significativamente a germinação das sementes e o crescimento das mudas de tomate em casa de vegetação. Essa cepa P10 suprimiu ainda mais a murcha de Verticillium do tomate com incidência de doença muito menor e pontuações de índice de doença sendo observadas após o tratamento com P10 em relação a plantas não tratadas em experimentos baseados em vasos. As plantas de tomate que foram tratadas com a cepa P10 também aumentaram as enzimas relacionadas à defesa, peroxidase, superóxido dismutase e atividade da catalase após o desafio de V. dahliae em relação às plantas que não foram tratadas com essa bactéria endofítica. Os resultados revelaram que a cepa bacteriana P10 tem valor potencial como agente de biocontrole para uso na prevenção da murcha de Verticillium em tomate.
Subject(s)
Solanum lycopersicum , Verticillium , Prunus domestica , Plant Diseases/prevention & control , Ascomycota , Bacillus subtilis , FusariumABSTRACT
Resumen Introducción: Los protistas del género Labyrinthula causan la denominada "Enfermedad del desgaste" en el pasto marino, Thalassia testudinum. Desde el 2008 los monitoreos en el Caribe colombiano han mostrado variación espacial y temporal en la incidencia de la enfermedad, pero sin la alta mortalidad observada en otras regiones del mundo. Objetivo: Analizar algunos parámetros epidemiológicos en T. testudinum y comparar metabolitos entre plantas sanas e infectadas. Métodos: Registramos la severidad, incidencia y prevalencia de esta enfermedad en el Parque Nacional Natural Tayrona e Isla de Providencia, y analizamos muestras de agua y sedimentos. Además, aplicamos cromatografía líquida y de gases, junto con espectrometría de masas, a extractos metanólicos de muestras de hojas y rizomas de brotes sanos e infectados. Resultados: Las praderas se encontraban en buen estado, a pesar de la escasez de brotes de fanerógamas marinas en Tayrona y una alta incidencia (15 %) y severidad (355 %) de la enfermedad en Providencia. Las plantas infectadas tenían niveles más bajos de fenoles, flavonoides y azúcares. Las flavonas sulfatadas con aglicona luteolina y diosmetina, los esteroles (sitosterol y estigmasterol) y las oxilipinas volátiles se acumularon en las hojas (3-hidroxi-2-isopentanona) y los ácidos isopentanoico y octadecatrienoico en los rizomas. Conclusiones: Estos pastos marinos colombianos tienen producción diferencial de metabolitos. Probablemente como una defensa exitosa, aún a niveles bajos de severidad (0.1 %) e incidencia (1 %) de la enfermedad.
Abstract Introduction: Protists of the genus Labyrinthula cause the so-called "Wasting Disease" in seagrass, Thalassia testudinum. Monitoring in the Colombian Caribbean since 2008 has shown spatial and temporal variation in the disease's incidence, but without the high mortality observed in other regions of the world. Objective: To analyze some epidemiological parameters in T. testudinum and to compare metabolites between healthy and infected plants. Methods: We recorded severity, incidence and prevalence of this disease in Tayrona National Natural Park and Providencia Island, and we analyze water and sediment samples. Additionally, we applied gas and liquid chromatography, coupled with mass spectrometry, to methanolic extracts from leaf and rhizome samples of healthy and infected shoots. Results: The meadows were in good condition, despite the scarce seagrass shoots in Tayrona and a high incidence (15 %) and severity (35.5 %) of the disease in Providencia. Infected plants had lower levels of phenols, flavonoids and sugars. Sulphated flavones with aglycone luteolin and diosmetin, sterols (sitosterol and stigmasterol) and volatile oxylipins are accumulated in leaves (3-hydroxy-2-isopentanone) and isopentaenoic and octadecatrienoic acids in rhizomes. Conclusions: These Colombian seagrasses have differential production of metabolites. Probably as a successful defense, even at low levels of severity (0.1 %) and incidence (1 %) of the disease.
Subject(s)
Plant Diseases , Hydrocharitaceae , Metabolism , MusaABSTRACT
The cultivation of passion fruit is important for Brazil, since the country is currently the largest producer and consumer of fruit in the world. However, the fields of passion fruit still face important problems due to the incidence and severity of diseases in the field. Thus, the present study aimed to assess resistance to bacterial and fungal diseases in 13 genotypes of sour, sweet and wild passion fruit, in field conditions in the Distrito Federal, Brazil. For this, a field experiment was installed in a randomized block design, with four replications and 13 treatments (genotypes). The characteristics of incidence, severity and degree of resistance for bacteriosis, septoriosis, scab and anthracnose diseases were evaluated in 5 fruits per plot of each genotype. Genetic parameters of the evaluated traits were also estimated. High heritability values and CVg/Cve ratio were observed for most of the evaluated characteristics. The genotypes presented mean values of incidence and severity of bacteriosis, septoriosis, scab and anthracnose different among them, and the one that presented the best results in the degree of resistance for all diseases was F1 (MAR20 # 24 x ECL7 P1 R4).
Subject(s)
Plant Diseases , Bacteria , Xanthomonas , Cladosporium , Colletotrichum , Passiflora , FungiABSTRACT
Vegetables are an important source of income and high-value crops for small farmers. Chilli (Capsicum spp.) is one of the most economically important vegetables of Pakistan and it is grown throughout the country. It is a rich source of nutrition especially vitamins A, B, C and E along with minerals as folic acid, manganese (Mn), potassium (K) and molybdenum (Mo). Chilli possesses seven times more amount of vitamin C than an orange. Vitamin A, C and betacarotenoids are strong antioxidants to scavenge the free radicals. Chilli production is restricted due to various biotic factors. Among these viruses, Chilli veinal mottle virus (ChiVMV) is one of the most destructive and menacing agents that inflicts heavy and colossal losses that accounted for 50% yield loss both in quality and quantity. Pathogen-Derived Resistance (PDR) approach is considered one of the effective approaches to manage plant viruses. In this study, ChiVMV was characterized on a molecular level, the coat protein (CP) gene of the virus was stably transformed into Nicotiana benthamiana plants using Agrobacterium tumefaciens. The transgenic plants were challenged with the virus to evaluate the level of resistance of plants against the virus. It was observed that the plants expressing CP gene have partial resistance against the virus in terms of symptoms' development and virus accumulation. Translation of this technique into elite chilli varieties will be resulted to mitigate the ChiVMV in the crop as well as an economic benefit to the farmers.
Vegetais são uma importante fonte de renda e culturas de alto valor para os pequenos agricultores. A pimenta-malagueta (Capsicum spp.) é uma das hortaliças mais importantes economicamente do Paquistão e é cultivada em todo o país. É uma rica fonte de nutrição, especialmente vitaminas A, B, C e E com minerais como ácido fólico, manganês (Mn), potássio (K) e molibdênio (Mo). O pimentão possui sete vezes mais vitamina C do que a laranja. Vitaminas A e C e betacarotenoides são antioxidantes fortes para eliminar os radicais livres. A produção de pimenta é restrita devido a vários fatores bióticos. Entre esses vírus, o ChiVMV é o agente mais destrutivo e ameaçador que inflige perdas pesadas e colossais que representam 50% da perda de rendimento, tanto em qualidade quanto em quantidade. A abordagem de resistência derivada de patógenos (PDR) é considerada uma das abordagens eficazes para gerenciar os vírus de plantas. Neste estudo, ChiVMV foi caracterizado em nível molecular e o gene CP do vírus foi transformado de forma estável em plantas Nicotiana benthamiana usando Agrobacterium tumefaciens. As plantas transgênicas foram desafiadas com o vírus para avaliar seu nível de resistência contra o vírus. Observou-se que as plantas que expressam o gene CP apresentam resistência parcial ao vírus em termos de desenvolvimento de sintomas e acúmulo de vírus. A tradução dessa técnica em variedades de pimenta de elite resultará na mitigação do ChiVMV na safra, bem como em benefícios econômicos para os agricultores em termos de melhor rendimento e baixo custo de produção.
Subject(s)
Tobacco/genetics , Potyvirus/genetics , Pakistan , Plant Diseases/genetics , Plants, Genetically Modified/genetics , Disease ResistanceABSTRACT
En Guatemala, la producción del cultivo de papa se ve afectada por los nematodos Globodera rostochiensis y Globo-dera pallida. La capacidad de ambas especies para formar quistes complica su control y provoca el aumento de sus poblaciones. En Guatemala se reporta la presencia de ambas especies de nematodos por identificación morfológica, sin embargo, no se ha realizado una confirmación molecular. Este es el primer estudio para validar la presencia de ambas especies de nematodos por PCR múltiple y la determinación de la diversidad y estructura genética de las poblaciones utilizando marcadores moleculares. Se realizaron muestreos en cuatro departamentos productores de papa del país. La identificación por PCR se realizó con el cebador común ITS5 y los cebadores PITSr3 específico para G. rostochiensisy PITSp4 para G. pallida. La caracterización molecular se realizó con el marcador AFLP. Se confirmó la presencia de las dos especies de nematodos en los cuatro departamentos. Los índices de diversidad Shannon y heterocigosidad esperada revelaron mayor diversidad genética en G. rostochiensis (H = 0.311, He = 0.301) que en G. pallida (H = 0.035, He = 0.223). Los métodos NJ, DAPC y PCA exhibieron una débil estructura entre las poblaciones de ambas especies de nematodos. Los resultados sugieren un patrón de dispersión desde Quetzaltenango hacia el resto del país, atribuido a la comercialización de semilla contaminada con nematodos. Se sugiere promover programas de socialización sobre los beneficios del uso de semilla certificada, además de constantes monitoreos moleculares para un diagnóstico certero de ambas especies de nematodos.
In Guatemala, potato crop production is affected by the nematodes Globodera rostochiensis and Globodera pallida. The ability of both species to form cysts complicates their control and causes an increase in their populations. In Guatemala, both species of nematodes have been reported by morphological identification; however, molecular confirmation has not been carried out. It is the first study to validate the presence of both nematode species by multiplex PCR and determine the diversity and genetic structure of the populations using molecular markers. Sampling was carried out in four pota-to-producing departments of the country. PCR identification was performed with the common primer ITS5 and the primers PITSr3 specific for G. rostochiensis and PITSp4 for G. pallida. We performed molecular characterization with the AFLP marker. We confirmed the presence of the two nematode species in the four departments. Shannon diversity and expected heterozygosity indices revealed higher genetic diversity in G. rostochiensis (H = 0.311, He = 0.301) than in G. pallida (H = 0.035, He = 0.223). The NJ, DAPC, and PCA methods exhibited weak structure among populations of both nematode species. The results suggest a dispersal pattern from Quetzaltenango to the rest of the country, attributed to the commer-cialization of seed contaminated with nematodes. We suggest promoting socialization programs on the benefits of using certified seeds and constant molecular monitoring for an accurate diagnosis of both species of nematodes.
Subject(s)
Genetic Variation/genetics , Solanum tuberosum/parasitology , Multiplex Polymerase Chain Reaction/methods , Nematoda/genetics , Parasites/parasitology , Plant Diseases/parasitology , Seeds/parasitology , Genetic Structures/genetics , Guatemala , Nematoda/pathogenicityABSTRACT
The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai, widely cultivated in China. A new disease of Z. latifolia was found in Zhejiang Province, China. Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths. The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf, causing sheath rot and death of entire leaves on young plants. The pathogen was isolated and identified as the bacterium Pantoea ananatis, based on 16S ribosomal RNA (rRNA) gene sequencing, multilocus sequence analysis (atpD (β-subunit of ATP synthase F1), gyrB (DNA gyrase subunit B), infB (translation initiation factor 2), and rpoB (β-subunit of RNA polymerase) genes), and pathogenicity tests. Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths, forming biofilms on the inner surface of vessel walls, and extended between vessel elements via the perforated plates. To achieve efficient detection and diagnosis of P. ananatis, species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z. latifolia. This is the first report of bacterial sheath rot disease of Z. latifolia caused by P. ananatis in China.
Subject(s)
Pantoea/genetics , Plant Diseases/microbiology , Poaceae/microbiology , VirulenceABSTRACT
The cultivation and production of cucumber are seriously affected by downy mildew caused by Pseudoperonospora cubensis. Downy mildew damages leaves, stems and inflorescences, and then reduces the yield and quality of cucumber. This review summarized the research advances in cucumber downy mildew, including pathogen detection and defense pathways, regulatory factors, mining of pathogens-resistant candidate genes, proteomic and genomic analysis, and development of QTL remarks. This review may facilitate clarifying the resistance mechanisms of cucumber to downy mildew.
Subject(s)
Cucumis sativus/genetics , Oomycetes/genetics , Peronospora , Plant Diseases/genetics , ProteomicsABSTRACT
Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.
Subject(s)
Animals , Cell Nucleus , Hemiptera/metabolism , Insect Vectors/genetics , Insecta , Nucleocapsid Proteins/metabolism , Oryza , Plant Diseases , Tenuivirus/metabolism , Virus ReplicationABSTRACT
We aimed to investigate the effects of Calendula officinalis and Echinacea purpurea extracts in terms of growth parameters, antibacterial activity and phenolic profile in tomato infected by Clavibacter michiganensis subsp. michiganensis (CmmT7). A significant difference was observed in E. purpuraextract, indicating the highest effects on plant height (27.25 cm), fresh plant weight (28.45 cm), root length (24.42 cm), and root weight (6.74 g) (p<0.05). Moreover, Calendula officinalis and Echinacea purpurea extracts showed significant inhibitory activity against CmmT7 (p<0.05). Among phenolic compounds, the only chlorogenic acid amounts were varied in the tomato seedlings leaves with C. officinalis extract (K3) + CmmT7, E. purpurea extract (E3) + CmmT7 and CmmT7 (p<0.01). Moreover, chlorogenic acid amount was approximately 9 times higher than in CmmT7-treated leaves when compared to control. The results showed that application of the extracts of these plants had a significant influence on bacterial canker and growth parameters.
Nuestro objetivo fue investigar los efectos de los extractos de Calendula officinalis y Echinacea purpurea en términos de parámetros de crecimiento, actividad antibacteriana y perfil fenólico en tomate infectado por Clavibacter michiganensis subsp. michiganensis (CmmT7). Se observó una diferencia significativa en el extracto de E. purpura, que indica los mayores efectos sobre la altura de la planta (27,25 cm), el peso de la planta fresca(28,45 cm), la longitud de la raíz (24,42 cm) y el peso de la raíz (6,74 g) (p<0,05). Además, los extractos de Calendula officinalis y Echinacea purpurea mostraron una actividad inhibidora significativa contra CmmT7 (p<0,05). Entre los compuestos fenólicos, las únicas cantidades de ácido clorogénico se variaron en las hojas de las plántulas de tomate con extracto de C. officinalis (K3) CmmT7, extracto de E. purpurea(E3) CmmT7 y CmmT7 (p<0.01). Además, la cantidad de ácido clorogénico fue aproximadamente 9 veces mayor que en las hojas tratadas con CmmT7 en comparación con el control. Los resultados mostraron que la aplicación de los extractos de estas plantas tuvo una influencia significativa sobre el cancro bacteriano y los parámetros de crecimiento.
Subject(s)
Plant Extracts/pharmacology , Calendula/chemistry , Echinacea/chemistry , Clavibacter/drug effects , Anti-Bacterial Agents/pharmacology , Plant Diseases , Plants, Medicinal , Plant Extracts/chemistry , Microbial Sensitivity Tests , Solanum lycopersicum , Plant Leaves , Phenolic Compounds/analysis , Anti-Bacterial Agents/chemistryABSTRACT
Abstract Xanthomonas oryzae pv. oryzae (Xoo), a pathogen responsible for rice bacterial leaf blight, produces biofilm to protect viable Xoo cells from antimicrobial agents. A study was conducted to determine the potency of Acacia mangium methanol (AMMH) leaf extract as a Xoo biofilm inhibitor. Four concentrations (3.13, 6.25, 9.38, and 12.5 mg/mL) of AMMH leaf extract were tested for their ability to inhibit Xoo biofilm formation on a 96-well microtiter plate. The results showed that the negative controls had the highest O.D. values from other treatments, indicating the intense formation of biofilm. This was followed by the positive control (Streptomycin sulfate, 0.2 mg/mL) and AMMH leaf extract at concentration 3.13 mg/mL, which showed no significant differences in their O.D. values (1.96 and 1.57, respectively). All other treatments at concentrations of 6.25, 9.38, and 12.5 mg/mL showed no significant differences in their O.D. values (0.91, 0.79, and 0.53, respectively). For inhibition percentages, treatment with concentration 12.5 mg/mL gave the highest result (81.25%) followed by treatment at concentrations 6.25 and 9.38 mg/mL that showed no significant differences in their inhibition percentage (67.75% and 72.23%, respectively). Concentration 3.13 mg/mL resulted in 44.49% of biofilm inhibition and the positive control resulted in 30.75% of biofilm inhibition. Confocal laser scanning microscopy (CLSM) analysis of Xoo biofilm inhibition and breakdown showed the presence of non-viable Xoo cells and changes in aggregation size due to increase in AMMH leaf extract concentration. Control slides showed the absence of Xoo dead cells.
Resumo Xanthomonas oryzae pv. oryzae (Xoo), um patogênico responsável pela influência bacteriana na folha do arroz, produz biofilme para proteger células Xoo viáveis de agentes antimicrobianos. Foi conduzido um estudo para determinar a potência do extrato de folha de Acacia mangium methanol (AMMH) como um inibidor de biofilme Xoo. Quatro concentrações (3,13, 6,25, 9,38 e 12,5 mg/mL) de extrato de folha de AMMH foram testadas quanto à sua capacidade de inibir a formação de biofilme Xoo em uma placa de microtitulação de 96 poços. Os resultados mostraram que os controles negativos tiveram o maior valor de OD do que os outros tratamentos, indicando a intensa formação de biofilme. Isso foi seguido do controle positivo (sulfato de estreptomicina, com concentração de 0,2 mg/mL, e extrato de folha de AMMH, com concentração de 3,13 mg/mL), que não apresentou diferenças significativas nos seus valores OD (1,96 e 1,57, respectivamente). Todos os outros tratamentos com concentrações de 6,25, 9,38, e 12,5 mg/mL não tiveram diferenças significativas nos seus valores OD (0,91, 0,79, e 0,53, respectivamente). Para percentagens de inibição, o tratamento com concentração 12,5 mg/mL apresentou o maior resultado (81,25%), seguido do tratamento em concentrações de 6,25 e 9,38 mg/mL, que não mostraram diferenças significativas na sua percentagem de inibição (67,75 e 72,23%, respectivamente). Concentração 3,13 mg/mL resultou em 44,49% de inibição do biofilme, e o controle positivo resultou em 30,75% de inibição do biofilme. Análise por microscopia confocal de leitura a laser de inibição e separação de biofilme Xoo revelou a presença de células Xoo não viáveis e alterações no tamanho da agregação por causa do aumento na concentração de extrato de folha de AMMH. Slides de controle mostraram a ausência de células Xoo mortas.
Subject(s)
Oryza , Acacia , Plant Diseases , Xanthomonas , Plant Extracts/pharmacology , Biofilms , MethanolABSTRACT
Abstract The use of more than one control technique can maximize the reduction of the damages caused by the fungus Asperisporium caricae causal agent of the black spot in the papaya crop. The objective of this work was to evaluate the sensitivity of the fungi Hansfordia pulvinata and Acremonium spp. to alternative products with potential for use in the control of the black-spotted ptarmigan. Three isolates of Acremonium spp. (A-598, A-602 and A-617) and an isolate of H. pulvinata (H-611) were grown in BDA medium containing Agro-Mos®, Bion®, Ecolife®, Hortifospk®, Matriz G®, Vitaphol® separately. The Amistar 500WG ® fungicide was used as a positive control and pure BDA as a negative control. The toxicity of the tested products was determined based on the values of the biological index, derived from the means of mycelial growth, sporulation and germination of conidia, in each experimental unit. In this way it was possible to select the products classified as compatible for all isolates, and to test them in vivo. In the greenhouse, only the isolates and isolates with selected products, were applied in papaya plants with foliar symptoms of black-spotted. The incidence of leaves with hyperparasites and the percentage of black-painted lesions colonized by the tested isolates were evaluated. Thus, the H-611 isolate proved to be compatible with most of the alternative products tested, except with Hortifos®. Bion® and Matrix® products were compatible with all tested isolates and could be used in conjunction with Acremonium spp. and H. pulvinata to control the papaya black spot, since these products did not present toxicity on the hyperparasitic fungi.
Resumo O uso de mais de uma técnica de controle pode maximizar a redução dos danos causados pelo fungo Asperisporium caricae agente causal da pinta preta na cultura do mamoeiro. O objetivo deste trabalho foi avaliar a sensibilidade dos fungos Hansfordia pulvinata e Acremonium spp. a produtos alternativos com potencial para uso no controle da pinta-preta. Três isolados de Acremonium spp. (A-598, A-602 e A-617) e um isolado de H. pulvinata (H-611) foram cultivados em meio BDA contendo Agro-Mos®, Bion®, Ecolife®, Hortifospk®, Matriz G®, Vitaphol® separadamente. Fungicida Amistar 500WG® foi utilizado como controle positivo e BDA puro, como controle negativo. A toxicidade dos produtos testados foi determinada com base nos valores do índice biológico, provenientes das médias do crescimento micelial, esporulação e germinação de conídios, em cada unidade experimental. Dessa forma foi possível selecionar os produtos classificados como compatíveis para todos os isolados, e testá-los in vivo. Em casa de vegetação, somente os isolados e os isolados com produtos selecionados, foram aplicados em plantas de mamoeiro com sintomas foliares de pinta-preta. Avaliaram-se a incidência de folhas com hiperparasitas e a porcentagem de lesões de pinta-preta colonizadas pelos isolados testados. Assim o isolado H-611 mostrou-se compatível com a maioria dos produtos alternativos testados, exceto com Hortifos®. Os produtos Bion® e Matriz® apresentaram compatibilidade com todos os isolados testados, podendo ser utilizados em conjunto com o Acremonium spp. e H. pulvinata para controlar a pinta-preta do mamoeiro, uma vez que estes produtos não apresentaram toxidade sobre os fungos hiperparasitas.
Subject(s)
Carica , Plant Diseases , AscomycotaABSTRACT
Trollius chinensis is a traditional Chinese medicinal material in China, the wild resource of T. chinensis are now exhausted, and commercial medicinal T. chinensis mainly depends on artificial cultivation. As one of the most severely happened diseases at the seedling period, damping off has been a serious threaten to the breeding of T. chinensis seedlings. However, no related research have been reported so far. So, the authors collected damping-off samples of T. chinensis in 2018 from seedling breeding nursery in Guyuan, Hebei province, and carried out study on taxonomic identification of the pathogen. Damping off occurs in the T. chinensis production area from mid-May to late June every year. At the beginning, brown lesions were observed on the basal stem, then the lesions circumferential expanded and constricted, and finally resulted in the fall and death of T. chinensis seedlings. Pathogenic isolate was growing rapidly on the PDA medium, well developed aerial mycelia were grey white at first, then turned brown gradually, and a great number of small dark brown sclerotia were developed in the middle and periphery of the colony. Mycelial diameter of the pathogen was about 7 to 10 μm, near right angle or acute angle branches, near branches with septa, branches and septa with constriction. After the healthy T. chinensis seedlings were inoculated by pathogenic isolate, damping-off was observed soon, and the symptom was as same as those observed in the field. Through homogenous blast, the rDNA-ITS sequence of the pathogenic isolate shown 99.49% to 99.84% homology with Rhizoctonia solani, R. solani AG-1 IC mycelium anastomosis group and Thanatephorus cucumeris, the sexual type of Rhizoctonia. Furthermore, obvious mycelial anastomosis phenomena were observed when the pathogenic isolate and R. solani AG-1 IC strain were confronting cultured. Based on the results above, the pathogenic isolate causing damping off of T. chinensis was identified as R. solani AG-1 IC mycelial anastomosis group. RESULTS:: in the present work have important significance for further research on basic biology of the pathogen and integrated control of damping off causing by it on T. chinensis.
Subject(s)
Basidiomycota , Plant Breeding , Plant Diseases , Rhizoctonia , SeedlingsABSTRACT
Medicinal plants are beneficial to human health. However,most of the major producing regions of medicinal plants suffer from rust disease,which threatens the yield and quality of Chinese medicinal materials,thus causes huge economic loss,and hinders the sustainable development of the Chinese medicine industry. By the end of 2020,rust disease had been reported in medicinal plants of 76 species and 33 families. In the 76 species,79 rust pathogens were detected. The majority of these pathogens belonged to Puccinia( 33,39. 24%),Coleosporium( 14,15. 19%),and Aecidium( 11,13. 92%). Of these 79 rust pathogens,10 were autoecious and 13 were heteroecious. Through literature research,this study reviewed the symptoms,pathogen species,severity and distribution,prevalence and occurrence conditions,and control measures of rust disease in medicinal plants,and thereby summarized the research status of rust disease in medicinal plants and the gap with other plants,which is expected to serve as a reference for further research on rust disease in medicinal plants.
Subject(s)
Humans , Basidiomycota/genetics , Plant Diseases , Plants, MedicinalABSTRACT
BACKGROUND: Rice sheath blight (caused by Rhizoctonia solani) and tobacco mosaic virus are very important plant diseases, causing a huge loss in global crop production. Paenibacillus kribbensis PS04 is a broad-spectrum biocontrol agent, used for controlling these diseases. Previously, extracellular polysaccharides (EPS) from P. kribbensis PS04 had been purified and their structure was inferred to be fructosan. This study aimed to evaluate the effects of exogenous EPS treatment on plantpathogen interactions. RESULTS: Plant defense genes such as phenylalanine ammonia-lyase, catalase, chitinase, allene oxide synthase, and PR1a proteins were significantly induced by exogenous EPS treatment. Moreover, subsequent challenge of EPSpretreated plants with the pathogens (R. solani or tobacco mosaic virus) resulted in higher expression of defenseassociated genes. Increased activities of defense-associated enzymes, total phenols, and flavonoids were also observed in EPS pretreated plants. The contents of malondialdehyde in plants, which act as indicator of lipid peroxidation, were reduced by EPS treatment. CONCLUSIONS: This study comprehensively showed that EPS produced from P. kribbensis PS04 enhances disease resistance in plants by the activation of defense-associated genes as well as through the enhancement of activities of defense-related enzymes.