Influence of Ethylene on Increased Susceptibility of Oranges to<i>Diplodia natalensis</i>

Barmore, Charles R.

doi:10.1094/pd-69-228

Cited by 23 publications

(20 citation statements)

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“…A subsequent study was conducted using fruit from HLB-affected groves (there are few if any unaffected citrus groves in Florida at this time) using normal-looking AS fruit from trees asymptomatic for HLB disease versus HLB S fruit. The fruit side of AZ-C from 70 Hamlin Diplodia infection is known to cause SER, and the incidence of SER is exacerbated by exposure to ethylene (28). Therefore, three batches of 100 Hamlin fruit (50 AS and 50 S) and 100 Valencia fruit (50 AS and 50 S) were used in a decay assay, with or without ethylene treatment.…”

Section: Resultsmentioning

confidence: 99%

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High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Zhao

Bai

McCollum

et al. 2015

Appl Environ Microbiol

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Huanglongbing (HLB), presumably caused by the bacterium "Candidatus Liberibacter asiaticus," is a devastating citrus disease associated with excessive preharvest fruit drop. Lasiodiplodia theobromae (diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, diplodia was found in "Ca. Liberibacter asiaticus"-positive juice from HLB-symptomatic fruit (S) but not in "Ca. Liberibacter asiaticus"-negative juice. Therefore, the incidence of diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of diplodia in the AZ-C of HLB-symptomatic (S; "Ca. Liberibacter asiaticus" threshold cycle [C T ] of <30) than in the AZ-C of in asymptomatic (AS; "Ca. Liberibacter asiaticus" C T of >30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia C T values were negatively correlated with ethylene production (R ‫؍‬ ؊0.838 for Hamlin; R ‫؍‬ ؊0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R ‫؍‬ 0.855 for Hamlin; R ‫؍‬ 0.850 for Valencia), suggesting that diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop. C itrus huanglongbing (HLB; also known as citrus greening) is one of the most devastating diseases of citrus and has spread throughout the major citrus-producing regions in Asia, Africa, and the Americas, causing great losses for the citrus industry worldwide (1). HLB is associated with "Candidatus Liberibacter" spp., which are Gram-negative, phloem-limited bacteria (2, 3). The Asian form of HLB is currently present in the United States, and the causal pathogen, bacterium "Candidatus Liberibacter asiaticus," was first confirmed in Southeast Florida in 2005 (1) and now is prevalent in all Florida citrus-growing areas in the state. HLB disease causes substantial economic loss by debilitating the productive capacity and shortening the life span of infected trees, promoting fruit drop and reducing fruit quality (4). Yield reduction can reach 30 to 100%, depending on the proportion of the canopy affected and the age of the trees during inoculation (1, 5).HLB-diseased citrus plants develop a multitude of symptoms. Leaf symptoms include chlorosis, which commonly appears in an asymmetric pattern referred to as "blotchy mottle" (4). Chlorosis may typically appear on a single branch and subse...

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Section: Resultsmentioning

confidence: 99%

“…The occurrence of SER is greatly enhanced by exposure to ethylene, which is commonly used to enhance the color development of the fruit (28,29). Ethylene is a gaseous plant hormone that promotes chlorophyll degradation, ripening of climacteric fruits, senescence, and fruit abscission (30).…”

mentioning

confidence: 99%

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Zhao

Bai

McCollum

et al. 2015

Appl Environ Microbiol

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“…A doença assume maior importancia em regiões quentes e úmidas, como Flórida e Caribe (Brown & Eckert, 2000). A elevada incidência desta doença em laranja 'Pêra' TABELA 1 -Incidência (%) 1 de doenças pós-colheita em laranjas 'Valência' produzidas em sistema orgânico (O) e convencional (C), aos 14 dias de armazenamento a 25°C (11,8%), em Recife, foi atribuída à temperatura do local de armazenamento dos frutos, em torno de 30°C, aliada ao uso do etileno para o desverdecimento dos frutos (Dantas et al, 2003), que causa a abscisão precoce do cálice, facilitando a entrada do patógeno que se encontra latente nesse tecido (Barmore & Brown, 1985).…”

Section: Resultados E Discussão Doenças Pós-colheitaunclassified

Doenças pós-colheita em laranja 'Valência' e caracterização da população fúngica em pomares orgânicos e convencionais

Fischer¹,

Zanette²,

Spósito³

et al. 2011

Trop. plant pathol.

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RESUMOA agricultura orgânica busca atender a demanda crescente por alimentos saudáveis, produzidos sem agroquímicos. Este trabalho objetivou: a) caracterizar as doenças pós-colheita em laranjas 'Valência' provenientes de cultivo orgânico e convencional; b) caracterizar a micoflora ambiental nos pomares citrícolas e c) detectar a presença de isolados de Penicillium spp. resistentes aos fungicidas tiabendazol e imazalil nos pomares. Frutos coletados nos pomares e no mercado atacadista de São Paulo (CEAGESP) foram armazenados durante 14 dias a 25ºC e 85% de UR. A incidência de doenças foi avaliada visualmente a cada dois-três dias. A micoflora ambiental foi amostrada com placas de Petri, contendo meio batata-dextrose-ágar acrescido ou não dos fungicidas. As maiores incidências de doenças foram observadas nas laranjas orgânicas em relação as do sistema convencional. A principal doença detectada foi a podridão peduncular de lasiodiplodia. A micoflora total do ambiente, assim como os principais gêneros fúngicos não diferiram significativamente entre os pomares amostrados. Cladosporium foi o gênero fúngico mais abundante nos pomares. A frequência de isolados de P. digitatum resistentes a tiabendazol foi semelhante nos pomares, com média de 47,3% dos isolados. A frequência de isolados de P. digitatum resistentes a imazalil foi baixa (2,6%), não sendo constatados isolados resistentes a tiabendazol + imazalil. Palavras-chave: Citrus sinensis, Penicillium spp., citros, podridões, resistência a fungicidas. ABSTRACT Postharvest diseases in orange fruits and characterization of the fungal population in organic and conventional farmersOrganic farming aims to meet growing demand for healthy foods, produced without the use of pesticides. The purposes of this work were a) to characterize postharvest diseases in 'Valencia' oranges grown under organic and conventional conditions; b) to characterize the environmental mycoflora in citrus orchards and c) to detect the presence of Penicillium spp. isolates resistant to fungicides thiabendazole and imazalil in the orchards. Citrus fruit collected at the orchards and at the wholesale market of São Paulo (CEAGESP) were stored during 14 days at 25ºC and 85% UR. The incidence of postharvest diseases was evaluated visually every two-three days. The environmental mycoflora was sampled according to the gravimetric method, using Petri dishes containing potato-dextrose-agar medium, supplemented or not with fungicides. The highest incidence of diseases was observed in oranges sampled in organic orchards in comparison to the conventional system. The most frequent postharvest disease was lasiodiplodia stem-end rot. The environmental mycoflora and the population of the major genera of fungi did not differ significantly among the sampled orchards. Cladosporium was the most prevailing genus in the orchards. The frequency of P. digitatum isolates resistant to thiabendazole was similar in orchards, with an average of 47.3%. The frequency of P. digitatum isolates resistant to imazalil was low (2.6%), and...

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“…A podridão de Lasiodiplodia tem maior importância em regiões de clima quente e úmido, como na Florida e Caribe (Brown & Eckert, 2000). A elevada incidência em Recife foi atribuída à temperatura do local de armazenamento dos frutos, em torno de 30°C, aliada ao uso do etileno para o desverdecimento dos frutos, que causa a abscisão precoce do botão, facilitando a entrada do patógeno que se encontra latente nos tecidos necróticos do botão (Barmore & Brown, 1985).…”

Section: Doençaunclassified

Caracterização dos danos pós-colheita em citros procedentes de "packinghouse"

et al. 2007

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As doenças pós-colheita representam um sério obstáculo à citricultura, uma vez que comprometem a qualidade e quantidade dos frutos colhidos. Este trabalho objetivou caracterizar as injúrias pós-colheita de frutos de laranja 'Pêra', 'Lima' e 'Natal' e de tangor 'Murcott', destinados ao mercado interno, após diferentes etapas do beneficiamento em "packinghouse". Foram coletados cem frutos na chegada ao "packinghouse", na banca de embalagem e no palete, após embalamento em caixas de madeira. Os frutos foram individualizados e submetidos à câmara úmida por 24 horas, permanecendo por mais 20 dias a 25ºC e 85% de umidade relativa. A incidência de podridões foi avaliada visualmente após a retirada da câmara úmida e a cada três dias. Os patógenos fúngicos encontrados tiveram a patogenicidade confirmada através da inoculação em frutos sadios. Não houve diferença significativa na incidência de doenças pós-colheita nas diferentes fases do processamento nas variedades Lima e Natal. Na variedade Pêra e no tangor 'Murcott', a incidência de doenças foi menor nas amostras coletadas na chegada ao "packinghouse". O bolor verde (Penicillium digitatum) foi a principal doença encontrada nos diferentes frutos cítricos. Outras doenças importantes foram a antracnose (Colletotrichum gloeosporioides), as podridões pedunculares (Lasiodiplodia theobromae e Phomopsis citri) e a podridão azeda (Geotrichum candidum).

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Influence of Ethylene on Increased Susceptibility of Oranges toDiplodia natalensis

Cited by 23 publications

References 0 publications

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Doenças pós-colheita em laranja 'Valência' e caracterização da população fúngica em pomares orgânicos e convencionais

Caracterização dos danos pós-colheita em citros procedentes de "packinghouse"

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