Wounding induces the first enzyme of the shikimate pathway in Solanaceae

Dyer, William E.; Henstrand, John M.; Handa, Avtar K.; Herrmann, Klaus M.

doi:10.1073/pnas.86.19.7370

Cited by 120 publications

(75 citation statements)

References 32 publications

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“…Outra explicação para este aumento dos valores de firmeza seria a lignificação dos tecidos, pois o corte e o descasque podem provocar a ativação de mecanismos de defesa culminando na deposição de lignina e suberina nas paredes das células injuriadas (DIXON; PAIVA, 1995;DYER et al, 1989), possivelmente seguido da subdivisão celular sob o tecido suberizado para a recomposição da periderme (BURTON, 1982). PINELI (2005) atribui também à desidratação e a deposição de lignina e suberina como os fatores responsáveis pelo aumento de firmeza e outras alterações superficiais observadas em batatas minimamente processadas embaladas na ausência de vácuo.…”

Section: Firmezaunclassified

Mandioca minimamente processada submetida a radiação gama

Vieites

Daiuto

Carvalho³

et al. 2012

Sem. Ci. Agr.

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ResumoA mandioca minimamente processada é uma alternativa para prolongar o período de comercialização das raízes, agregando de valor a matéria prima e atendendo as necessidades do consumidor que procura produtos de fácil preparo. O objetivo desta pesquisa foi avaliar a qualidade de mandioca minimamente processada submetida radiação gama. No processamento mínimo foram utilizadas raízes de mandioca (IAC-567-70) e, após o preparo foram acondicionadas em embalagens de poliestireno expandido e revestidas por filme plástico de polietileno de baixa densidade (PEBD) sendo irradiadas nas doses 0,0 (controle), 0,5; 1,0; 1,5; 2,0 KGy. Foi obtido ainda outro tratamento cujas, raízes foram acondicionadas em embalagem de nylon+ polietileno com aplicação de vácuo. As raízes acondicionadas de todos os tratamentos foram armazenadas sob refrigeração (5 ± 1 ºC) e avaliações realizadas aos 0, 3, 6, 9 e 12 dias. As análises realizadas foram: acidez titulável, pH, firmeza, coloração, atividade da enzima polifenoloxidase, tempo de cocção e porcentagem de hidratação das raízes. As avaliações seguiram apenas até o 9º dia de armazenamento, pois após este período as raízes já apresentavam alterações fisiológicas e microbiológicas detectadas visualmente. Para acidez titulável, as raízes embaladas a vácuo obtiveram os menores valores, seguido do controle acondicionado em bandejas. Para os demais tratamentos observou-se aumento dos valores de acidez, tendo este comportamento influenciado nos valores de pH. Para os demais parâmetros avaliados não ocorreu diferença significativa entre tratamentos, mas foram observadas alterações com o armazenamento. A firmeza diminuiu com o armazenamento. Os valores de luminosidade e componente de cor amarela diminuíram com o armazenamento e os valores de cor b* (verde) aumentaram. A atividade da enzima polifenoloxidase foi máxima no dia de elaboração do produto e diminuiu com o armazenamento. O tempo de cozimento e porcentagem de hidratação diminuíram com o armazenamento das raízes. Palavras-chave: Manihot esculenta CRANTZ, polifenoloxidase, tempo de cocção, cor AbstractFresh cut cassava is an alternative to prolong roots commercialization period, adding value to the raw material and assisting the consumer's needs that seeks for products of easy preparation. The aim of this work was to evaluate the quality of fresh cut cassava subjected to gamma radiation. For processing cassava roots (IAC -567-70) were used, after preparation were packed in expanded polystyrene (EPS) trays, covered by low density polyethylene (LDPE) plastic film, being subjected to gamma radiation in the doses 0 (control), 0.5; 1.0; 1.5; 2.0 KGy. Another treatment was also carried out in which roots were vacuum packed in nylon + polyethylene. Packed roots of all treatments were stored under

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Section: Firmezaunclassified

Mandioca minimamente processada submetida a radiação gama

Vieites

Daiuto

Carvalho³

et al. 2012

Sem. Ci. Agr.

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“…DAHP synthase catalyzes the entry step of the shikimate pathway and in microorganisms is regulated transcriptionally and is also subjected to feedback regulation by Phe at the enzyme level (Bentley, 1990;Herrmann and Weaver, 1999). In plants, DAHP synthase genes are transcriptionally regulated and induced in response to various environmental stimuli (Dyer et al, 1989;Keith et al, 1991;Gö rlach et al, 1995). At the enzyme level, however, all plant DAHP synthases examined to date are insensitive to Phe (Huisman and Kosuge, 1974;Suzich et al, 1985;Herrmann, 1995).…”

Section: Regulation Of the Shikimate Pathway Leading To Phe Biosynthesismentioning

confidence: 99%

RNAi Suppression of Arogenate Dehydratase1 Reveals That Phenylalanine Is Synthesized Predominantly via the Arogenate Pathway in Petunia Petals

et al. 2010

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L-Phe, a protein building block and precursor of numerous phenolic compounds, is synthesized from prephenate via an arogenate and/or phenylpyruvate route in which arogenate dehydratase (ADT) or prephenate dehydratase, respectively, plays a key role. Here, we used Petunia hybrida flowers, which are rich in Phe-derived volatiles, to determine the biosynthetic routes involved in Phe formation in planta. Of the three identified petunia ADTs, expression of ADT1 was the highest in petunia petals and positively correlated with endogenous Phe levels throughout flower development. ADT1 showed strict substrate specificity toward arogenate, although with the lowest catalytic efficiency among the three ADTs. ADT1 suppression via RNA interference in petunia petals significantly reduced ADT activity, levels of Phe, and downstream phenylpropanoid/benzenoid volatiles. Unexpectedly, arogenate levels were unaltered, while shikimate and Trp levels were decreased in transgenic petals. Stable isotope labeling experiments showed that ADT1 suppression led to downregulation of carbon flux toward shikimic acid. However, an exogenous supply of shikimate bypassed this negative regulation and resulted in elevated arogenate accumulation. Feeding with shikimate also led to prephenate and phenylpyruvate accumulation and a partial recovery of the reduced Phe level in transgenic petals, suggesting that the phenylpyruvate route can also operate in planta. These results provide genetic evidence that Phe is synthesized predominantly via arogenate in petunia petals and uncover a novel posttranscriptional regulation of the shikimate pathway.

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“…Tissue-specific expression of mRNA for each of two DAHP synthase genes has been shown in tomato (Gorlach et al, 1993(Gorlach et al, ,1994. Environmental signals also affect DAHP synthase gene expression; DAHP synthase mRNA and activity levels are induced by abiotic stresses such as mechanical wounding (Dyer et al, 1989) and glyphosate (Pinto et al, 1988) in potato, as well as by light and funga1 elicitors in parsley Plant Physiol. Vol.…”

mentioning

confidence: 99%