Web blight (Thanatephorus cucumeris): a new disease on leaves of okra plants

Gasparotto, L.; Kano, Cristiaini; Ceresini, Paulo Cézar; Pereira, J. R.; Cardoso, M. O.; Pereira, Daniel; Castroagudín, Vanina Lilián

doi:10.1590/1808-1657000252016

Cited by 4 publications

(3 citation statements)

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“…Within the R. solani AG‐1 complex, we also detected the occurrence of the AG‐1 ID infecting cowpea in Roraima. This AG was reported in Brazil first in 2010 and secondly in 2017, as associated with several hosts in the Amazon, including the Fabaceae common bean (Gaino et al , ; Gasparotto et al , ).…”

Section: Discussionmentioning

confidence: 82%

A broad diversity survey of Rhizoctonia species from the Brazilian Amazon reveals the prevalence of R. solani AG‐1 IA on signal grass and the new record of AG‐1 IF on cowpea and soybeans

et al. 2020

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Leaf blight, sheath blight, and web blight are major diseases caused by Rhizoctonia species on both Fabaceae and Poaceae plant hosts in the Brazilian Amazon agroecosystem. To determine the diversity of Rhizoctonia species associated with foliar diseases on fabaceous (cowpea and soybean) and poaceous (rice and signal grass [Urochloa brizantha]) hosts, a broad survey was conducted in Pará, Rondônia, Roraima, and Mato Grosso, in the Amazon, from 2012 to 2013. We extended our survey to Cerrado areas of Mato Grosso, and the lowlands of Paraíba Valley, in São Paulo, where these Rhizoctonia foliar diseases have not been reported so far. Our findings revealed that these diseases are caused by a diversity of Rhizoctonia solani AG‐1 complex. We detected that R. solani AG‐1 IA (sexual phase Thanatephorus cucumeris) was the predominant pathogen associated with signal grass leaf blight and collar rot diseases in the Amazon, especially in Rondônia and northern Mato Grosso. In addition, a subgroup of R. solani (AG‐1 IF), not previously reported in Brazil, was associated with leaf blight on cowpea and soybean, in Roraima. Another subgroup (AG‐1 ID) was also detected in Roraima. In Mato Grosso Cerrados we did not find any of the major Rhizoctonia foliar pathogens. Instead, R. oryzae (Waitea circinata) was the predominant species associated with a collar rot on U. brizantha. In the lowlands of São Paulo, R. oryzae‐sativae (Ceratobasidium oryzae‐sativae) was the predominant pathogen detected causing the rice sheath spot disease.

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Section: Discussionmentioning

confidence: 82%

A broad diversity survey of Rhizoctonia species from the Brazilian Amazon reveals the prevalence of R. solani AG‐1 IA on signal grass and the new record of AG‐1 IF on cowpea and soybeans

et al. 2020

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“…For instance, B. cinerea is a worldwide occurring plant pathogen, causing pre- and postharvest gray mold rot on a large number of fruit, vegetables, and flower crops [ 31 , 32 , 33 , 34 ]. T. cucumeris is among the most important soil-borne pathogens all over the world, causing leaf, root, and fruit blight and rot on rice, tomatos, beans, okra crops, and more [ 35 , 36 , 37 ]. In the present study, virulence curves showed that TDDE displayed strong fungicidal activity against B. cinerea and T. cucumeris with EC 50 values of 1.401 μg/mL and 0.464 μg/mL, respectively ( Figure 4 B and Table 2 ), while the EC 50 values of MBC against B. cinerea is 7.40 ± 1.68 [ 38 ].…”

Section: Discussionmentioning

confidence: 99%

Bioassay-Guided Isolation of Broad-Spectrum Fungicidal Active Compound from Artemisia ordosica

Tang

Yang

et al. 2021

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To avoid the widespread resistance of commercial fungicides, new broad-spectrum botanical fungicides need to be developed. In previous bioactive screening assays, extracts of Artemisia ordosica Krasch. (A. ordosica) had highly antifungal activities, but the responsible phytochemicals were unidentified. In this study, active compounds of A. ordosica extracts were identified using a bioassay-guided method, and antifungal assays were performed in vitro and in vivo. The bioactive compounds were dissolved in petroleum ether, and the best antifungal fraction contained four compounds: trans-dehydromatricaria ester (TDDE), 7, 4-demetylnringenin, capillarin, and stearic acid. Among them, TDDE exhibited the highest antifungal activity against six pathogenic fungi and five bacteria. It exhibited significant fungicidal activity against Thanatephorus cucumeris and Botrytis cinerea with EC50 values of 0.464 μg/mL and 1.4 μg/mL, respectively. The living tissue bioassay results showed that the relative protection effects (RPE) of TDDE on tomato leaves, tomato fruit, and strawberry leaves infected with B. cinerea reached 76.78%, 86.2%, and 80.89%, respectively. In pot experiments, the RPE on tomato and strawberry plants infected with B. cinerea reached 84.11% and 96.37%, respectively. Morphological and physiological examination showed that TDDE had significant inhibitory effects on mycelial growth, including increased top offshoot, contorted hyphal tips, and extravasated cytochylema. Meanwhile, bactericidal activities of TDDE were significantly higher than kanamycin and streptomycin in five bacteria, and the plant tissue experiments further demonstrated that it had an 88.31% RPE on walnut leaves infected with Xanthomonas campestris pv. jugiandis, 72.18% RPE on potato infected with Erwinia carotovora subsp. carotovora, and 82.50% RPE on kiwifruit branches infected with Pseudomonas syringae pv. actinidiae. The active compounds isolated from A. ordosica in this study show great potential value for developing broad-spectrum fungicides, and also provide an important way to identify and isolate new bioactive products from medicinal plants.

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“…Em 2010, por meio de reconstrução filogenética, Gaino et al (13) confirmaram que R. solani AG 2 estava associado à mancha areolada da seringueira na Amazônia porém os isolados de seringueira eram divergentes dos demais membros do AG 2 descritos mundialmente, os quais incluíram: AG 2-1, AG 2-2 IIIB, AG 2-2 IV, AG 2-2 LP e AG 2-3 (7). Isolados de outros AGs de R. solani tais como AG 1 ID, IF [recentemente reclassificados de IB (14)] e de Rhizoctonia sp. binucleada (AG R, associado à fase sexuada de Ceratobasidium), oriundos de hospedeiros distintos, também infectaram seringueira (13).…”

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Mancha areolada de Thanatephorus da seringueira na Amazônia: identificação filogenética e variação genética em populações do patógeno

Basseto¹,

Vicentini

Gasparotto

et al. 2019

Summa phytopathol.

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RESUMO A mancha areolada de Thanatephorus é uma das doenças mais importantes da seringueira (Hevea brasiliensis) na Amazônia. Apesar disso, questão importante sobre o real posicionamento filogenético deste patógeno ainda não foi respondida. Neste estudo, nós analisamos os padrões de variação genética em seqüências da região ITS-5.8S do rDNA de uma população de T. cucumeris (fase assexuada = Rhizoctonia solani AG 2-2) associado à mancha areolada da seringueira amostrada em Belém (Pará), Manaus (Amazonas) e Xapuri/Rio Branco (Acre) na Amazônia, e comparando-a filogeneticamente com membros do complexo AG 2 descritos mundialmente. Este estudo representa um passo importante para revelar a etiologia da fase assexuada de T. cucumeris da seringueira. Filogeneticamente, por análise Bayesiana, encontramos suporte para nomear um novo grupo de anastomose de R. solani associado à mancha areolada da seringueira: o AG 2-2 Hb. Este grupo constitui-se numa unidade evolutiva independente em relação aos subgrupos mundiais do AG 2-2 analisados. Na genealogia gênica construída por análise coalescente, observou-se que a população de R. solani AG 2-2 Hb de Belém é relativamente mais velha que as demais populações analisadas. O ancestral comum de todas as três populações analisadas está associado com a mancha foliar do maracujazeiro (Passiflora edulis), em Belém e tem cerca de 0,8 unidades evolutivas coalescentes de idade. Nenhum haplótipo da região ITS-5.8S do AG 2-2 Hb de Belém foi observado em outras regiões. Entretanto, a população de Manaus compartilhou dois, de seus quatro haplótipos, com aqueles observados em Xapuri / Rio Branco, no Acre, indicando fluxo gênico.

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Web blight (Thanatephorus cucumeris): a new disease on leaves of okra plants

Cited by 4 publications

References 3 publications

A broad diversity survey of Rhizoctonia species from the Brazilian Amazon reveals the prevalence of R. solani AG‐1 IA on signal grass and the new record of AG‐1 IF on cowpea and soybeans

A broad diversity survey of Rhizoctonia species from the Brazilian Amazon reveals the prevalence of R. solani AG‐1 IA on signal grass and the new record of AG‐1 IF on cowpea and soybeans

Bioassay-Guided Isolation of Broad-Spectrum Fungicidal Active Compound from Artemisia ordosica

Mancha areolada de Thanatephorus da seringueira na Amazônia: identificação filogenética e variação genética em populações do patógeno

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