Function of polyphenol oxidase in higher plants

Vaughn, Kevin C.; Duke, Stephen O.

doi:10.1111/j.1399-3054.1984.tb04258.x

Cited by 315 publications

(185 citation statements)

References 41 publications

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“…In Figure 2 the minimum of reflectance near 678 nm should be mostly due to chlorophyll a (spectral region I), whereas the little shoulder near 650 nm should be related to chlorophyll b absorption (spectral region I′), as suggested by Merzlyak et al 23 In comparison with the control spectrum, the exposed one ( Figure 2) showed a decrease in reflectance in region II. This trend, emerging during browning, may be explained by the generation of melanin-like pigments, 5,24 for example, via the oxidation of polyphenols by polyphenol oxidases. 25 In the blue and green region (Figure 2, region III), no significant difference was recorded.…”

Section: ■ Discussionmentioning

confidence: 99%

“…This results in the formation of polymerized melanin-like pigments. 5 The appearance and the extent of this disorder are strongly dependent on factors such as grape variety, berry stage of development, 2 and environmental conditions. 6 During the past years, our research group has been particularly involved in the phenotypic evaluation of germplasm within the framework of COST Action FA1003 "Grapenet: East−West Collaboration for Grapevine Diversity Exploration and Mobilization of Adaptive Traits for Breeding".…”

Section: ■ Introductionmentioning

confidence: 99%

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Characterization of Grape (Vitis vinifera L.) Berry Sunburn Symptoms by Reflectance

Rustioni

Rocchi

Guffanti

et al. 2014

J. Agric. Food Chem.

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Sunburn can affect grape quality both for chemical modifications and by visual impact of the browning. Optical properties of 17 white grape accessions were investigated in the visible region using a noninvasive instrument. Reflectance spectra were obtained using a Jaz System spectrometer. Browning was induced by exposing grape bunches to direct sunlight at 12:30 p.m. for 5 h. During the experiment, the global solar radiation ranged from 2.6 to 2.7 MJ m −2 h −1 and the air temperature from 24.3 to 29.2°C; the exposed berries reached a temperature of 34.2°C in comparison to the 30.4°C of the shaded ones. Differences between the spectra of controlled and exposed berries mainly emphasized the loss in chlorophyll and the formation of brown compounds. A positive correlation between the chlorophyll concentration and berry browning was proposed. Developing rapid, noninvasive, and low-cost methods based on reflectance spectroscopy could support grapevine variety characterization with respect to sunburn susceptibility as well as study of the physiological processes involved in the symptoms' appearance.

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Section: ■ Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Characterization of Grape (Vitis vinifera L.) Berry Sunburn Symptoms by Reflectance

Rustioni

Rocchi

Guffanti

et al. 2014

J. Agric. Food Chem.

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“…PPOs are found throughout the plant kingdom (Mayer and Harel, 1979;Vaughn and Duke, 1984;Mayer, 1987;Vaughn et al, 1988;Sherman et al, 1991), and they probably play a role in defense against pathogens and herbivores (Vö rö s et al., 1957;Felton et al, 1989;Duffey and Felton, 1991;Constabel and Ryan, 1998;Stout et al, 1999;Gatehouse, 2002). They are plastid-localized copper metalloenzymes that catalyze the oxidation of o-diphenols to o-diquinones (diphenolase activity; EC 1.10.3.2) and, in some species, also the o-hydroxylation of monophenols (monophenolase activity; EC 1.14.18.1; Vaughn et al, 1988;Mayer, 2006).…”

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confidence: 99%

Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species

et al. 2009

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Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenoloxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution.

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“…Figueiredo (1994) verificou que em P. maximum o teor de fenóis totais aumentou com o incremento de flúor, tendo as plantas tratadas acumulado 80% mais fenóis que as plantas do controle. O acúmulo de compostos fenólicos é um mecanismo de defesa das plantas ativado por fatores bióticos e abióticos que induzem ao estresse (Vaughn & Duke, 1984).…”

Section: Resultsunclassified

“…Figueiredo (1994), evidenciou, em C. gayana 25% mais fenóis nas plantas tratadas que nas testemunhas, sendo essa concentração menor que a verificada em P. maximum. A ocorrência de fenóis em C. gayana comprova a presença de injúrias na folha, mesmo em ausência de sintomas visíveis, pois compostos fenólicos, como citado por Vaughn & Duke, (1984) são comumente associados ao mecanismo de defesa das plantas a fatores estressantes. O aumento na quantidade de compostos fenólicos presentes nos tecidos com a progressão da injúria foi também registrado por Hasemann et al (1990) em Picea abies.…”

Section: Resultsunclassified

Ação do flúor dissolvido em chuva simulada sobre a estrutura foliar de Panicum maximum jacq. (colonião) e Chloris gayana kunth. (capim-rhodes) - Poaceae

et al. 2002

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RESUMO -(Ação do flúor dissolvido em chuva simulada sobre a estrutura foliar de Panicum maximum jacq. (colonião) e Chloris gayana kunth. (capim-rhodes) -Poaceae) Panicum maximum e Chloris gayana foram submetidas à chuvas simuladas com soluções de fluoreto de potássio (15mg ml -1 ) com objetivo de identificar as injúrias causadas pelo flúor (F -), como poluente atmosférico, na estrutura da lâmina foliar e fornecer subsídios para a seleção de características diagnósticas a serem utilizadas na bioindicação. Os principais sintomas foram clorose e necrose, principalmente no ápice e margens das lâminas. Nos cortes transversais, quatro tipos de alterações causadas pelo flúor são relacionadas: redução do número, tamanho e arranjo dos cloroplastos; necrose dos tecidos principalmente nas margens das folhas; erosões na superfície da folha e hipertrofia das células. Em C. gayana, no entanto, não foram observadas as alterações nos cloroplastos e os outros sintomas foram bem mais discretos que em P. maximum. A ocorrência de compostos fenólicos foi registrada pela coloração com fucsina em todas as regiões da lâmina onde foram observadas lesões. Ao microscópio eletrônico de varredura foi observado o achatamento e formação de concavidades nas paredes externas das células. Este experimento confirma a maior sensibilidade de P. maximum ao flúor e revela algumas características anatômicas de C. gayana que, entre outros fatores, podem estar contribuindo para a maior resistência desta espécie a este poluente.Palavras-chave -Anatomia, Poaceae, bioindicadores, flúor, poluição ABSTRACT -(The action of dissolved fluoride in artificial rain on leaf structure of Panicum maximum Jacq. (colonião) and Chloris gayana Kunth. (capim-rhodes) -Poaceae) P. maximum and C. gayana were treated with potassium fluoride artificial rain (15 mg ml -1 ) to identify injury caused by fluoride (F -), as an atmospheric pollutent, on the leaf structure of these two species, providing diagnostics characteristics for plant selection to be used as

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Function of polyphenol oxidase in higher plants

Cited by 315 publications

References 41 publications

Characterization of Grape (Vitis vinifera L.) Berry Sunburn Symptoms by Reflectance

Characterization of Grape (Vitis vinifera L.) Berry Sunburn Symptoms by Reflectance

Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species

Ação do flúor dissolvido em chuva simulada sobre a estrutura foliar de Panicum maximum jacq. (colonião) e Chloris gayana kunth. (capim-rhodes) - Poaceae

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