Aberrant Processing of Polyphenol Oxidase in a Variegated Grapevine Mutant

Rathjen, Anne H.; Robinson, Simon P.

doi:10.1104/pp.99.4.1619

Cited by 45 publications

(46 citation statements)

References 23 publications

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“…PPO B is the most abundant PPO mRNA in young tomato leaves (nodes 1-3); levels of this transcript subsequently decline as leaves mature (node 5 ) . The presence of PPO transcripts primarily at early developmental stages has been observed previously in tomato, potato, and grape berries (Rathjen and Robinson, 1992;Shahar et al, 1992;Hunt et al, 1993;Thygesen et al, 1995). In contrast, broad bean PPO transcripts are abundant in mature leaves (Cary et al, 1992).…”

Section: Discussionmentioning

confidence: 52%

Differential Expression and Turnover of the Tomato Polyphenol Oxidase Gene Family during Vegetative and Reproductive Development

1997

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Polyphenol oxidases (PPOs) are encoded by a highly conserved, seven-member gene family clustered within a 165-kb locus on chromosome 8 of tomato (Lycopersicon esculentum). Using gene-specific probes capable of differentiating between PPO A/C, PPO B, PPO D, and PPO E/F, we examined the spatial and temporal expression of this gene family during vegetative and reproductive development. RNA blots and in situ hybridization using these probes showed that although PPO expression is primarily confined to early stages of development, the steady-state mRNA levels of these genes are subject to complex patterns of spatial and temporal regulation in vegetative and reproductive organs. Young tomato leaves and flowers possess the most abundant PPO transcripts. PPO B is the most abundant in young leaves, whereas in the inflorescence PPO B and E/F transcripts are dominant. Differential expression of PPOs is also observed in various trichome types. PPO A/C are specifically expressed in type I and type IV trichomes. In contrast, PPO D is only expressed in type VI trichomes. Type I, IV, and VI trichomes possess PPO E/F transcripts. Immunolocalization verified the translational activity of PPOs identified by in situ hybridization and suggested cell-type-specific, developmentally programmed PPO turnover. In addition, immunolocalization demonstrated the accumulation of PPO in specific idioblast cells of stems, leaves, and fruits.

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Section: Discussionmentioning

confidence: 52%

Differential Expression and Turnover of the Tomato Polyphenol Oxidase Gene Family during Vegetative and Reproductive Development

1997

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“…As protease inhibitors did not modify the activation rate, the activation process could not be ascribed to the existence of a proenzyme, as it has been described for insect, crustacean and Ðsh phenolases (Wang et al 1994 ; Aspan et al 1995). Rathjen and Robinson (1992) for grapevine PPO and So derha ll (1995) for carrot PPO also suggested that a ProPPO, a 60 kDa molecule, was converted into its active form (a 40 kDa PPO) by a limited proteolysis. Addition of detergent (SDS), alcohol (ethanol), fatty acid (linoleic acid) or protease (trypsin) to pear PPO crude extract enhanced the activation rate (Fig 1).…”

Section: Resultsmentioning

confidence: 91%

“…Several factors have been postulated to be involved in activation. They include : (i) a proenzyme (Rathjen and Robinson 1992 ;Aspan et al 1995 ;So derha ll 1995) ; (ii) a PPO-bound inhibitor (Sanchez-Ferrer et al 1993) ; and (iii) a conformational change (Lerner and Mayer 1975 ;Marques et al 1994).…”

Section: Introductionmentioning

confidence: 98%

Polyphenoloxidases from Williams Pear (Pyrus communis L, cv Williams): Activation, Purification and Some Properties

Gauillard

Richard‐Forget

1997

J. Sci. Food Agric.

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“…2). Proteolytic processing of many other PPOs has been described, such as the PPO enzymes found in broad bean leaf (Vicia faba; Robinson and Dry, 1992), grape (Vitis vinifera; Rathjen and Dry, 1992), and coffee (Coffea arabica; Mazzafera and Robinson, 2000). More recently, Flurkey and Inlow (2008) analyzed T. officinale (2), T. kok-saghyz (3), H. brasiliensis (4), and F. elastica (5); all the plants listed above were harvested after wounding by drawing into 10-mL microglass capillaries.…”

Section: Discussionmentioning

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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Aberrant Processing of Polyphenol Oxidase in a Variegated Grapevine Mutant

Cited by 45 publications

References 23 publications

Differential Expression and Turnover of the Tomato Polyphenol Oxidase Gene Family during Vegetative and Reproductive Development

Differential Expression and Turnover of the Tomato Polyphenol Oxidase Gene Family during Vegetative and Reproductive Development

Polyphenoloxidases from Williams Pear (Pyrus communis L, cv Williams): Activation, Purification and Some Properties

Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species

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